***Useful Information For The Working Sparky***

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“ Rcd's “

Fire detection circuits must be supplied independently of other circuits and not protected by an Rcd protecting multiple circuits. 560.7.1 All circuits in a bath shower room must be protected by a 30mA RCD. P166, 701.411.3.3
Where applicable an RCD notice must be fixed on or next to the CCU 514.12.2 An RCD should not be used as a main switch 314.2 If the maximum Zs values for a circuit in a TN systems cannot be met, the circuit may be protected by a 30mA RCD. 531.3.1
If the maximum Zs values for a TN systems cannot be met, the installation may be protected by an 100mA RCD and treated as a TT systems . 531.3.1 : 411.5.1 : 411.5.2 : 411.5.3
Unless specifically labelled or suitably identified, all 13A socket outlets must be protected by a 30mA Rcd. 411.3.3
In a TN systems , the part of a lighting circuit in a bath or shower room is required to be 30mA RCD protected. 411.3.3 , 701.411.3.3

Where a cable is buried in a wall or partition at a depth of less than 50mm on either side it must be sufficiently mechanically protected against penetration OR RCD protected AND installed either horizontally within 150mm of the top of the wall or vertically within 150mm of the angle formed where two walls meet or run horizontally or vertically to an accessory, luminaire or CCU 522.6.6 , 522.6.7 . This applies to a cable in a partition constructed using metallic parts other than fixings irrespective of the cable depth. 522.6.8

Surface run cables do not require RCD protection. OSG p22

A single RCD protecting a TT systems must be installed at the origin of the installation unless the part of the system between the origin and the RCD fulfils the requirements for protection by Class 11 equipment or equivalent insulation 531.4.1

All Electrical equipment must be accessible for operation , inspection & testing maintenance and repair. 132.12

Rcd Test Procedure

Many RCD test meters have a facility where tests can be carried out during the positive or negative half of the supply cycle. For tests 1 & 2 the RCD operating time to be recorded is the longer of the two measured during the half cycle tests.

DO NOT press the test button on the RCD before testing as this can temporarily reset a faulty RCD

Test 1
Adjust the current setting on the test meter to 100% of the rated trip current of the RCD and perform a test. A general purpose BS4293 RCD should operate within 200mS . A general purpose BS-61008 RCD or RCBO to BS-61009 should operate within 300ms

Test 2
An RCD provided for Basic Protection should have a rated TRIP current not exceeding 30mA If the RCD is rated at 30mA , adjust the current setting on the test meter to 150ma ( x5 ) and perform a test. The RCD must operate in a time not exceeding 40mS.
Test 3
Adjust the current setting on the test meter to 50% of the RCD trip current and perform a test. The RCD should not operate within 2 seconds
The Test Button : Finally operate the RCD by pressing its test button

 

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A typical 2500 kVA, 5.75% impedance transformer will have a short circuit capacity of 52,300 amps. The next highest standard size transformer at 3750 kVA will have a 6.5% impedance and would have a short circuit output capability of 69,395 amps which will be sufficient. ,


In the particular application discussed, the ratio of the selected standard size transformer kVA to motor kVA is 3750 kVA / 958.5 kVA = 3.91. Thus the transformer rating is 391% larger, or, nearly four times, the rating of the motor. Note the non-linear effect of the impedance rating of the transformers on their short circuit capacities ,

Transformer Connected To An Upstream Transformer ,

The second transformer we will examine will have a finite short circuit capacity available at its primary rather than an unlimited capacity. We will assume that a facility derives its power from the same 1000 kVA transformer mentioned above and that the
second transformer is connected directly to the terminals of the 1000 kVA transformer.
Thus, feeder cables between the two transformers are eliminated and the impedance of cables are not taken into account. However, the smaller the motor leads, the less will be both the short circuit capacity and the voltage delivered to the motor terminals ,

The second transformer, which will have a 480 volt primary and a 480 volt secondary, will be used to power a 20 HP, 3 phase, 460 volt motor which will be started at full voltage. The motor will be the only load on the transformer. The minimum transformer kVA ratings are for use with multiple motors on a single transformer. The 21.6 kVA is calculated as follows:

480 volts x 26 nominal amps x 1.732 = 21.6 kVA

The transformer manufacturers will give a 20 HP motor a nominal full load amp rating of 27 amps, thus allowing no extra capacity:
460 volts x 27 nominal amps x 1.732 = 21.5 kVA ,
One motor manufacturer has rated a 20 HP motor at 26 Full Load Amps, 460 VAC, 205 Locked Rotor Amps, 81% Power Factor. The motor will present a load of , 460 volts x 26 amps x 1.732 = 20.7 kVA ,
The starting motor kVA load with inrush current will be : 460 V x 205 A x 1.732 = 163.3 kVA ,

We will consider using a 30 kVA general purpose transformer to supply the 20 HP motor. The transformer will have a nominal impedance of 2.7% and an ouptut of 36.1 amps at 480 volts. The short circuit current capacity that can be delivered to the 21.6 kVA
transformer by the upstream 1000 kVA transformer is 20,924 amps, or, 17,395 kVA.
The short circuit amperage capacity of a transformer with a limited system short circuit capacity available at its primary is :

transformer full load amps / (transformer impedance + upstream system impedance as seen by the transformer)
Where : upstream system impedance as seen by the transformer = transformer kVA / available primary short circuit capacity kVA
Therefore, ( 36.1 amps / [2.7% + (30 kVA / 17,395 kVA ) = 36.1 / (2.7% + .0017%) = 36.1 / .0287 = 1258 short circuit amps )
The transformer output voltage drop upon motor inrush will be :
motor inrush kVA / short circuit kVA =163.3 kVA / (480 V x 1258 A x 1.732 ) = 163.3 kVA / 1046 kVA =156 = 15.6 % )
A 30 kVA transformer rating is too small as the motor voltage drop will exceed 10% ,

A 45 kVA transformer with a 2.4% impedance and an output of 54.1 amps at 480 volts would have a short circuit capacity of 2034 amps. The voltage drop upon motor inrush would be 9.66% ,

For a single motor and transformer combination, one transformer manufacturer recommends that the motor full load running current not exceed 65% of the transformer full load amp rating. [3] Thus, for our 26 amp motor the transformer rating should be a minimum of 40 amps, or, 33.3 kVA.

The transformer output voltage drop upon motor inrush will be : motor inrush kVA / short circuit kVA =
163.3 kVA / (480 V x 1258 A x 1.732) = 163.3 kVA / 1046 kVA = 156 = 15.6 %
A 30 kVA transformer rating is too small as the motor voltage drop will exceed 10% ,
A 45 kVA transformer with a 2.4% impedance and an output of 54.1 amps at 480 volts would have a short circuit capacity of 2034 amps. The voltage drop upon motor inrush ,
A 45 kVA transformer with a 2.4% impedance and an output of 54.1 amps at 480 volts would have a short circuit capacity of 2034 amps. The voltage drop upon motor inrush would be 9.66%. , A 45 kVA transformer with a 2.4% impedance and an output of 54.1 amps at 480 volts
would have a short circuit capacity of 2034 amps. The voltage drop upon motor inrush
would be 9.66% ,
For a single motor and transformer combination, one transformer manufacturer recommends that the motor full load running current not exceed 65% of the transformer full load amp rating. [3] Thus, for our 26 amp motor the transformer rating should be a minimum of 40 amps, or, 33.3 kVA. ,
Multiple Motors On A Single Transformer ,
The minimum transformer kVA is given by transformer manufacturers so that a transformer may be sized properly for multiple motors. If there are five motors on one transformer, add the minimum kVA ratings and then add transformer capacity as necessary to accommodate the inrush current of the largest motor , The transformer thusly selected will be capable of running and starting all five motors provided that only one motor is started at any one time. Additional capacity will be required for motors starting simultaneously , Also, if any motor is started more than once per hour, add 20% to that motor's minimum kVA rating to compensate for heat losses within the transformer.
Motor Contribution to Short Circuit Capacity ,
When a fault condition occurs, power system voltage will drop dramatically. All motors that are running at that time will not be able to sustain their running speed. As those motors slow in speed, the stored energy within their fields will be discharged into the power line. The nominal discharge of a motor will contribute to the fault a current equal to up to four times its full load current.
With our 1000 kVA, 1203 amp transformer example given above, we will assume that all
1203 amps of load are from motors. The actual short circuit current will equal 20,924 amps
plus 400% of 1203 amps for a total of 25,736 short circuit amps.

When sizing the transformer for motor loads, the fault current contribution from the motors will not be a consideration for sizing. However, the motor contribution must motors will not be a consideration for sizing. However, the motor contribution must be
considered when sizing all branch circuit fuses and circuit breakers. The interrupting capacity ratings of those devices must equal or exceed the total short circuit capacity ratings of those devices must equal or exceed the total short circuit capacity available at the point of application..

Motor contribution to short circuit capacity must be included when adding a variable frequency drive to the system ,

Do you know what an impedance test is ? Max Earth fault loop impedance is ( Zs=Ze+R1+R2 )
You are testing your ( R1 + R2 ) if there is no continuity of your CPC you will have an open circuit.


Easily check your Earth Loop Impedance compliance!
: Cable size and capacity
: Voltage drop in volt and percent
: Maximum length of run
: Fuse or Circuit Breaker size
: Working Temperature
: Fault level
: Minimum trip current needed to comply with Earth loop Impedance test
: Actual let through current
: Maximum impedance values (Ze) and the actual impedance values (in ohms)
: Total impedance values(Zs) for the complete installation (in ohms)

“ Inspection & Testing before into Service “ 2392-10 Electrical Installations should be Inspected and Tested as Necessary and Appropriate During and the End of Installation , Before they are taken into Service , to Verify that they are Safe to Use ,Maintain and Alter and Comply with Part P of the
Building Regulations and with any Other Relevant Parts of the Building Regulations

 

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Machinery and equipment must be maintained in efficient working order, so it is in good repair and kept safe -
This is required by Regulation 5, of the Provision and Use of Work Equipment Regulations 1998.

What is Three Phase Power ?

Three phase power is a method of electric power transmission using three wires.
Three phase power systems may have a neutral wire that allows the system to use a higher voltage while still allowing lower voltage single phase appliances. In high voltage distributions, it is not common to have a neutral wire, as the loads can simply be connected between phases :
Three phase power is a very efficient form of electrical power distribution. All three wires carry the same current and have a constantly balanced power load. Three phase power does not generally power domestic houses, and when it does, a main distribution board splits the load. Most domestic loads use single phase power.
Conductors used in the three phase power system are colour-coded. Most countries have their own colour codes. The colour codes of the wires vary greatly. There may be a standard for each installation, or there may be no standard at all :
Three phase power flow begins in a power station. An electrical power generator converts mechanical power into alternating electric currents. After numerous conversions in the distribution and transmission network, the power is transformed into the standard mains voltage. At this point, the power may have already been split into single phases or into three phases. With three phase power, the output of the transformer is usually star connected with the mains voltage, 230 volts in Europe and 120 volts in North America :
Electric motors are the most common use for three phase power. A three phase induction motor combines high efficiency, a simple design and a high starting torque. Three phase electric motors are commonly used in industry for fans, blowers, pumps, compressors and many other kinds of motor driven equipment. A three phase power motor is less costly than a single phase motor of the same voltage and rating :
Other systems that use three phase power include air conditioning equipment, electric boilers and large rectifier systems. The main reasons for using the three phase power system are efficiency and economy. While most three phase motors are quite big, there are examples of very small motors, such as computer fans. An inverter circuit inside the fan converts DC to a three phase AC current. This serves to decrease noise, as the torque from a three phase motor is very smooth, and it also increases reliability :

What are Electrical Transformers ?
The name itself offers a simple definition. Electrical transformers are used to transform electrical energy. How electrical transformers do so is by altering voltage, generally from high to low. Voltage is simply the measurement of electrons, how many or how strong, in the flow. Electricity can then be transported more easily and efficiently over long distances :
While power line electrical transformers are commonly recognized, there are other various types and sizes as well. They range from huge, multi-ton units like those at power plants, to intermediate, such as the type used on electric poles, and others can be quite small. Those used in equipment or appliances in your home or place of businesses are smaller electrical transformers and there are also tiny ones used in items like microphones and other electronics :
Probably the most common and perhaps the most necessary use of various electrical transformers is the transportation of electricity from power plants to homes and businesses. Because power often has to travel long distances, it is transformed first into a more manageable state. It is then transformed again and again, or “stepped down,” repeatedly as it gets closer to its destination :
When the power leaves the plant, it is usually of high voltage. When it reaches the substation the voltage is lowered. When it reaches a smaller transformer, the type found on top of electric poles, it is stepped down again. It is a continuous process, which repeats until the power is at a usable level :
You have likely seen the type of electrical transformers that sit on top of electric poles. These, like most electrical transformers, contain coils or “windings” that are wrapped around a core. The power travels through the coils. The more coils, the higher the voltage. On the other hand, fewer coils mean lower voltage :
Electrical transformers have changed industry. Electric power distribution is now more efficient than ever. Transformers have made it possible to transfer power near and far, in a timely, efficient, and more economical manner. Since many people do not wish to live in close proximity to a power plant, there is the added benefit of making it possible for homes and businesses that are quite a distance from power plants to obtain dependable, affordable electricity. Much of the electricity used today will have passed through many electrical transformers before it reaches users. Power distribution :

What are AC Motors ?
There are many different types and sizes of electric motors. Electric motors can be divided into two types: Alternating Current (AC) motors and Direct Current (DC) motors. An AC electric motor requires an alternating current, while a DC motor requires direct current.
AC motors are further subdivided into single phase and three phase motors. Single phase AC electrical supply is what is typically supplied in a home. Three phase electrical power is commonly only available in a factory setting. The most common single phase AC motor is known as a universal motor. This is because this motor can also run with DC current.
This type of motor is very inefficient but can be very inexpensively made. It is also used almost exclusively for small factional horse power AC motors. The other advantage this AC motor has is that the rotational speed of the motor can be easy changed. This type of AC motor is commonly found in mixers, hand drills, and any other application requiring variable speed and low cost and small size.
For larger single phase AC motors, a electrical component known as a capacitor is used to create a second phase from the single phase AC current. This type of AC motor is known as an induction motor and there are two basic types; a capacitor start motor and a capacitor run motor. The capacitor is used to create a second phase from the single phase power source and it is the interaction between these two phases that causes the motor to turn.
This introduction of a second phase eliminates the need for the brushes used in a universal AC motor. This greatly increases the both the efficiency of the AC motor and increases the life expectancy of the AC motor as brushes are a
major source of wear and failure. This type of motor is a fixed speed motor. It is commonly used as the drive for refrigerator compressors, shop air-compressors, and as a general utility type AC motor.
AC motors are usually sized in horsepower. The most common sizes are what are called fractional horsepower motors, i.e. ½ horse power or ¼ horsepower. Larger motors are typically only found in factories, where they can range in size to thousands of horsepower.
AC motors also come with various speed ratings. Speed is usually specified as rotations per minute (RPM) at no load condition. As the motor is loaded down, the speed will slow down. When the AC motor is running at its rated power draw, the speed of the shaft measured in RPM is the full load speed. If the electric motor is loaded too heavily, the motor shaft will stop. This is known as the stall speed and should be avoided. All of these speeds are typically listed on the specification sheet for an AC motor.
Finally, before you order an AC motor, you should determine the mounting type you require, the start up torque, the type of enclosure required, and the type of shaft output required :

 

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What is the Difference between a Generator and Inverter ?
The difference between an generator and an inverter may at first seem simple. However, as more research is done, the issue can quickly become confusing, especially to those who are not technically inclined and familiar with types of electricity. For example, while the definitions of an inverter and generator are clearly distinct, there are such things as inverter generators. However, though the terms may seem contradictory, they can be explained fairly easily.
Before discussing the difference between an inverter and generator, it is first necessary to understand a little about electrical currents. Electricity is divided into two types of currents, alternating current (AC) and direct current (DC). AC, a more common current for home use, works by allowing electrons to flow in two different directions. In DC currents, electrons flow only one way.
An inverter takes existing power that comes in the form of DC current and converts it to AC current. This is a popular option for those wanting to run home electronics in automobiles. Such cars often produce on DC current, which is not compatible with most electronics meant to run off standard outlets. Therefore, an inverter becomes necessary.
A generator, on the other hand, is a machine that converts mechanical energy into energy in an electrical form. In most cases, electric generators are responsible for the energy a home receives. Large-scale electrical generators may be powered by coal, natural gas or nuclear energy. A portable generator commonly uses gasoline, which is burned to create electrical energy. Generators usually produce AC electricity.
Simply stated, the difference between the two is that an inverter is only effective if there is already a source of electrical energy. It cannot generate its own. It can simply convert electrical energy that is already there. On the other hand, a traditional generator cannot make AC current into DC current.
On the other hand, there are things known as inverter generators. These are like traditional generators in that they convert some other form of energy into electrical energy. However, they produce AC power, which is then converted to DC power before being converted back to AC. The reason for this conversion is that the power gained during the process. It allows the generator to be more fuel efficient, as well as operate more quietly than standard generators.
Some people also confuse an inverter with a power converter, even using the terms interchangeably. However, a converter is used to change voltage from one level to another. For example, in Europe, a converter may be used to convert the voltage from 220 to 120, for electrical components meant to run on a lower voltage,

What is IPS ?
IPS, or integrated power systems, is simply a method of ensuring that the power supply needed to keep a place of business functional in the event of a problem with the primary source of energy. With so many of our home and work environments dependent on a steady supply of power, it is no wonder that the concept of IPS has gone from being a good idea to an essential. Here is some background on the concept of IPS and how many companies choose to implement their backup power supply procedures these days :
IPS plans and procedures are nothing new. As far back as the 1940’s, manufacturing facilities relied on backup power stations that could be run with gas generators in the event of a massive power failure. Hospitals also have operated with a full-fledged disaster recovery program that would ensure power to all vital functions, such as oxygen for the patients and enough power to keep operating rooms going in a crisis :
What is different today is that IPS strategies have become more sophisticated as technology has improved and demand for more reliable IPS options has become necessary. Where once a gas generator would be needed to power a small power station, many organizations can now relay on compact battery backups as part of the IPS escalation procedures :
In telephone, everything from switch stations to bridging centres will utilize state of the art battery backup that can last for in excess of twelve hours before losing power. Many IPS plans will still incorporate generator backup as well, usually as a third alternative if it appears that battery backup is about to fail. More frequently, businesses are beginning to incorporate solar panels and battery storage as part of the overall IPS directives for the organization :
The loss of valuable data as a result of a complete shutdown in the face of a power outage could be devastating to any business. Preparing a workable IPS plan, including an escalation procedure for implementing the backup power sources, ensures that even in the face of a short-term problem with a node on the national power grid, life will go on as usual :

What is a DC Motor ?
A direct current (DC) motor is a fairly simple electric motor that uses electricity and a magnetic field to produce torque, which turns the motor. At its most simple, a DC motor requires two magnets of opposite polarity and an electric coil, which acts as an Electromagnets. The repellent and attractive electromagnetic forces of the magnets provide the torque that causes the DC motor to turn.
If you've ever played with magnets, you know that they are polarized, with a positive and a negative side. The attraction between opposite poles and the repulsion of similar poles can easily be felt, even with relatively weak magnets. A DC motor uses these properties to convert electricity into motion. As the magnets within the DC motor attract and repel one another, the motor turns.
A DC motor requires at least one electromagnet. This electromagnet switches the current flow as the motor turns, changing its polarity to keep the motor running. The other magnet or magnets can either be permanent magnets or other Electromagnets. Often, the electromagnet is located in the centre of the motor and turns within the permanent magnets, but this arrangement is not necessary.
To imagine a simple DC motor, think of a wheel divided into two halves between two magnets. The wheel of the DC motor in this example is the electromagnet. The two outer magnets are permanent, one positive and one negative. For this example, let us assume that the left magnet is negatively charged and the right magnet is positively charged.
Electrical current is supplied to the coils of wire on the wheel within the DC motor. This electrical current causes a magnetic force. To make the DC motor turn, the wheel must have be negatively charged on the side with the negative permanent magnet and positively charged on the side with the permanent positive magnet. Because like charges repel and opposite charges attract, the wheel will turn so that its negative side rolls around to the right, where the positive permanent magnet is, and the wheel's positive side will roll to the left, where the negative permanent magnet is. The magnetic force causes the wheel to turn, and this motion can be used to do work.
When the sides of the wheel reach the place of strongest attraction, the electric current is switched, making the wheel change polarity. The side that was positive becomes negative, and the side that was negative becomes positive. The magnetic forces are out of alignment again, and the wheel keeps rotating. As the DC motor spins, it continually changes the flow of electricity to the inner wheel, so the magnetic forces continue to cause the wheel to rotate.
DC motors are used for a variety of purposes, including electric razors, electric car windows, and remote control cars. The simple design and reliability of a DC motor makes it a good choice for many different uses, as well as a fascinating way to study the effects of magnetic fields. Electromagnets

 

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What is MIG Welding ? you’ll see a lot in you careers !! tripping ,
MIG (Metal Inert Gas) welding, also sometimes called GMAW (gas metal arc welding), is a welding process that was originally developed back in the 1940's for welding aluminium and other non-ferrous metals. MIG welding is an automatic or semi automatic process in which a wire connected to a source of direct current acts as an electrodes joins two pieces of metal, as it is continuously passed through a welding gun. A flow of an inert gas (originally Argon ) is also passed through the welding gun at the same time as the wire electrode. This inert gas acts as a shield, keeping air borne contaminants away from the weld zone.
The primary advantage of MIG welding is that it allows metal to be welded much quicker than traditional welding "stick welding" techniques. This makes it ideal for welding softer metals such as aluminum. When MIG welding was first developed, the cost of the inert gas (i.e., argon) made the process too expensive for welding steel. However, over the years, the MIG welding process has evolved and semi inert gases such as carbon dioxide can now be used to provide the shielding function which makes MIG welding cost effective for welding steel.
Besides providing the capability to weld non-ferrous metals, MIG welding has other advantages:
• It produces long continuous welds much faster than tradition welding methods.
• Since the shielding gas protects the welding arc, MIG welding produces a clean weld with very little splatter.
• The versatility of MIG welding means it can be used with a wide variety of metals and alloys
The primary disadvantages of MIG welding are:
• The welding equipment is quite complex (MIG welding requires a source of direct current, a constant source and flow of gas as well as the continuously moving wire electrode). Plus, electrodes are available in a wide range of sizes and made from a number of metal types to match the welding application.
• The actual welding technique used for MIG welding is different from traditional welding practices, so there is learning curve associated with MIG welding even for experienced welders. For example, MIG welders need to push the welding puddle away from them and along the seam.
• The necessity for the inert gas shield means that MIG welding cannot be used in an open area where the wind would blow away the gas shield.
Since it's development in the middle of last century, MIG welding has become commonplace in many manufacturing operations. For example MIG welding is commonly used in the automobile industry because of its ability to produce clean welds, and the fact that it welds metals quickly.

ELECTRICAL INSTALLATION CERTIFICATES NOTES FOR FORMS 1 AND 2 : 17th Edition ,

1. The Electrical Installation Certificate is to be used only for the initial certification of a new installation or for an addition or alteration to an existing installation where new circuits have been introduced.
It is not to be used for a Periodic Inspection, for which a Periodic Inspection Report form should be used. For an addition or alteration which does not extend to the introduction of new circuits, a Minor Electrical Installation Works Certificate may be used.
The "original" Certificate is to be given to the person ordering the work (Regulation 632.1). A duplicate should be retained by the contractor.
(2) This Certificate is only valid if accompanied by the Schedule of Inspections and the Schedule(s) of Test Results.
(3) The signatures appended are those of the persons authorized by the companies executing the work of design, construction, inspection and testing respectively. A signatory authorized to certify more than one category of work should sign in each of the appropriate places.
(4) The time interval recommended before the first periodic inspection must be inserted (see IEE Guidance Note 3 for guidance).
(5) The page numbers for each of the Schedules of Test Results should be indicated, together with the total number of sheets involved.
(6) The maximum prospective fault current recorded should be the greater of either the short-circuit current or the earth fault current.
(7) The proposed date for the next inspection should take into consideration the frequency and quality of maintenance that the installation can reasonably be expected to receive during its intended life, and the period should be agreed between the designer, installer and other relevant parties :

TESTING :
NOTES ON SCHEDULE OF TEST RESULTS

*1 Type of supply is ascertained from the distributor or by inspection.
*2 Ze at origin. When the maximum value declared by the distributor is used, the effectiveness of the earth must be confirmed by a test. If measured the main bonding will need to be disconnected for the duration of the test.
*3 Prospective fault current (PFC). The value recorded is the greater of either the short-circuit current or the earth fault current. Preferably determined by enquiry of the distributor.
*4 Short-circuit capacity of the device is noted, see Table 7.2A of the On-Site Guide or Table 2.4 of GN3
The following tests, where relevant, shall be carried out in the following sequence:
Continuity of protective conductors, including main and supplementary bonding Every protective conductor, including main and supplementary bonding conductors, should be tested to verify that it is continuous and correctly connected.
*6 Continuity Where Test Method 1 is used, enter the measured resistance of the line conductor plus the circuit protective conductor (R1+ R2). See 10.3.1 of the On-Site Guide or 2.7.5 of GN3. During the continuity testing (Test Method 1) the following polarity checks are to be carried out: (a) every fuse and single-pole control and protective device is connected in the line conductor only (b) centre-contact bayonet and Edison screw lampholders have outer contact connected to the neutral conductor (c) wiring is correctly connected to socket-outlets and similar accessories. Compliance is to be indicated by a tick in polarity column 11.
(R1 + R2) need not be recorded if R2 is recorded in column 7.
*7 Where Test Method 2 is used, the maximum value of R2 is recorded in column 7. See 10.3.1 of the On-Site Guide or 2.7.5 of GN3.
*8 Continuity of ring final circuit conductors A test shall be made to verify the continuity of each conductor including the protective conductor of every ring final circuit. See 10.3.2 of the On-Site Guide or 2.7.6 of GN3.
*9, *10 Insulation Resistance All voltage sensitive devices to be disconnected or test between live conductors (line and neutral) connected together and earth. The insulation resistance between live conductors is to be inserted in column 9. The minimum insulation resistance values are given in Table 10.1 of the On-Site Guide or Table 2.2 of GN3. See 10.3.3(iv) of the On-Site Guide or 2.7.7 of GN3.
All the preceding tests should be carried out before the installation is energised.
*11 Polarity A satisfactory polarity test may be indicated by a tick in column 11. Only in a Schedule of Test Results associated with a Periodic Inspection Report is it acceptable to record incorrect polarity.
*12 Earth fault loop impedance Zs This may be determined either by direct measurement at the furthest point of a live circuit or by adding (R1 + R2) of column 6 to Ze. Ze is determined by measurement at the origin of the installation or preferably the value declared by the supply company used. Zs = Ze + (R1 + R2). Zs should be less than the values given in Appendix 2 of the On-Site Guide or Appx 2 of GN3.
*13 Functional testing The operation of RCDs (including RCBOs) shall be tested by simulating a fault condition, independent of any test facility in the device. Record operating time in column 13. Effectiveness of the test button must be confirmed. See Section 11 of the On-Site Guide or 2.7.15 and 2.7.18 of GN3.
*14 All switchgear and controlgear assemblies, drives, control and interlocks, etc must be operated to ensure that they are properly mounted, adjusted, and installed. Satisfactory operation is indicated by a tick in column 14.
Earth electrode resistance The earth electrode resistance of TT installations must be measured, and normally an RCD is required. For reliability in service the resistance of any earth electrode should be below 200 Ω. Record the value on Form 1, 2 or 6, as appropriate. See 10.3.5 of the On-Site Guide or 2.7.12 of GN3.

 

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GUIDANCE FOR RECIPIENTS
This safety Certificate has been issued to confirm that the electrical installation work to which it relates has been designed, constructed, inspected and tested in accordance with British Standard 7671 (the IEE Wiring Regulations).
You should have received an "original" Certificate and the contractor should have retained a duplicate. If you were the person ordering the work, but not the owner of the installation, you should pass this Certificate, or a full copy of it including the schedules, immediately to the owner.
The Certificate should be retained in a safe place and be shown to any person inspecting or undertaking further work on the electrical installation in the future. If you later vacate the property, this Certificate will demonstrate to the new owner that the electrical installation complied with the requirements of British Standard 7671 at the time the Certificate was issued. The Construction (Design and Management) Regulations require that for a project covered by those Regulations, a copy of this Certificate, together with schedules is included in the project health and safety documentation.
For safety reasons, the electrical installation will need to be inspected at appropriate intervals by a competent person. The maximum time interval recommended before the next inspection is stated on Page 1 under "Next Inspection".
This Certificate is intended to be issued only for a new electrical installation or for new work associated with an addition or alteration or to an existing installation. It should not have been issued for the inspection of an existing electrical installation. A "Periodic Inspection Report" should be issued for such an inspection.
The Certificate is only valid if a Schedule of Inspections and Schedule of Test Results are appended : Page 2 of (note 5) ,

ELECTRICAL INSTALLATION CERTIFICATE GUIDANCE FOR RECIPIENTS (to be appended to the Certificate)
This safety Certificate has been issued to confirm that the electrical installation work to which it relates has been designed, constructed, inspected and tested in accordance with British Standard 7671 (the IEE Wiring Regulations).
You should have received an "original" Certificate and the contractor should have retained a duplicate. If you were the person ordering the work, but not the owner of the installation, you should pass this Certificate, or a full copy of it including the schedules, immediately to the owner.
The Certificate should be retained in a safe place and be shown to any person inspecting or undertaking further work on the electrical installation in the future. If you later vacate the property, this Certificate will demonstrate to the new owner that the electrical installation complied with the requirements of British Standard 7671 at the time the Certificate was issued. The Construction (Design and Management) Regulations require that for a project covered by those Regulations, a copy of this Certificate, together with schedules is included in the project health and safety documentation.
For safety reasons, the electrical installation will need to be inspected at appropriate intervals by a competent person. The maximum time interval recommended before the next inspection is stated on Page 1 under "Next Inspection".
This Certificate is intended to be issued only for a new electrical installation or for new work associated with an addition or alteration to an existing installation. It should not have been issued for the inspection of an existing electrical installation. A "Periodic Inspection Report" should be issued for such a periodic inspection.
The Certificate is only valid if a Schedule of Inspections and Schedule of Test Results are appended :

ELECTRICAL INSTALLATION CERTIFICATE GUIDANCE FOR RECIPIENTS (to be appended to the Certificate)
This safety Certificate has been issued to confirm that the electrical installation work to which it relates has been designed, constructed, inspected and tested in accordance with British Standard 7671 (the IEE Wiring Regulations).
You should have received an "original" Certificate and the contractor should have retained a duplicate. If you were the person ordering the work, but not the owner of the installation, you should pass this Certificate, or a full copy of it including the schedules, immediately to the owner.
The Certificate should be retained in a safe place and be shown to any person inspecting or undertaking further work on the electrical installation in the future. If you later vacate the property, this Certificate will demonstrate to the new owner that the electrical installation complied with the requirements of British Standard 7671 at the time the Certificate was issued. The Construction (Design and Management) Regulations require that for a project covered by those Regulations, a copy of this Certificate, together with schedules is included in the project health and safety documentation.
For safety reasons, the electrical installation will need to be inspected at appropriate intervals by a competent person. The maximum time interval recommended before the next inspection is stated on Page 1 under "Next Inspection".
This Certificate is intended to be issued only for a new electrical installation or for new work associated with an addition or alteration to an existing installation. It should not have been issued for the inspection of an existing electrical installation. A "Periodic Inspection Report" should be issued for such a periodic inspection.
The Certificate is only valid if a Schedule of Inspections and Schedule of Test Results are appended :

NOTES ON COMPLETION OF MINOR ELECTRICAL INSTALLATION WORKS CERTIFICATE
Scope
The Minor Works Certificate is intended to be used for additions and alterations to an installation that do not extend to the provision of a new circuit. Examples include the addition of socket-outlets or lighting points to an existing circuit, the relocation of a light switch etc. This Certificate may also be used for the replacement of equipment such as accessories or luminaires, but not for the replacement of distribution boards or similar items. Appropriate inspection and testing, however, should always be carried out irrespective of the extent of the work undertaken.
Part 1 Description of minor works
1,2 The minor works must be so described that the work that is the subject of the certification can be readily identified.
4 See Regulations 120.3 and 120.4. No departures are to be expected except in most unusual circumstances. See also Regulation 633.1.
Part 2 Installation details
2 The method of fault protection must be clearly identified e.g. earthed equipotential bonding and automatic disconnection of supply using fuse/circuit-breaker/RCD.
4 If the existing installation lacks either an effective means of earthing or adequate main equipotential bonding conductors, this must be clearly stated. See Regulation 633.2.
Recorded departures from BS 7671 may constitute non-compliance with the Electricity Safety, quality and continuity Regulations 2002 (as amended) or the Electricity at Work Regulations 1989. It is important that the client is advised immediately in writing.
Part 3 Essential Tests
The relevant provisions of Part 6 (Inspection and Testing) of BS 7671 must be applied in full to all minor works. For example, where a socket-outlet is added to an existing circuit it is necessary to:
1 establish that the earthing contact of the socket-outlet is connected to the main earthing terminal
2 measure the insulation resistance of the circuit that has been added to, and establish that it complies with Table 61 of BS 7671
3 measure the earth fault loop impedance to establish that the maximum permitted disconnection time is not exceeded
4 check that the polarity of the socket-outlet is correct
5 (if the work is protected by an RCD) verify the effectiveness of the RCD.
Part 4 Declaration
1,3 The Certificate shall be made out and signed by a competent person in respect of the design, construction, inspection and testing of the work.
1,3 The competent person will have a sound knowledge and experience relevant to the nature of the work undertaken and to the technical standards set down in BS 7671, be fully versed in the inspection and testing procedures contained in the Regulations and employ adequate testing equipment.
2 When making out and signing a form on behalf of a company or other business entity, individuals shall state for whom they are acting.

 

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MINOR ELECTRICAL INSTALLATION WORKS CERTIFICATE

(REQUIREMENTS FOR ELECTRICAL INSTALLATIONS - BS 7671 [IEE WIRING REGULATIONS ) To be used only for minor electrical work which does not include the provision of a new circuit
GUIDANCE FOR RECIPIENTS
This safety Certificate has been issued to confirm that the electrical installation work to which it relates has been designed, constructed, inspected and tested in accordance with British Standard 7671 (the IEE Wiring Regulations).
You should have received an "original" Certificate and the contractor should have retained a duplicate. If you were the person ordering the work, but not the owner of the installation, you should pass this Certificate, or a full copy of it, immediately to the owner.
A separate Certificate should have been received for each existing circuit on which minor works have been carried out. This Certificate is not appropriate if you requested the contractor to undertake more extensive installation work, for which you should have received an Electrical Installation Certificate.
The Certificate should be retained in a safe place and be shown to any person inspecting or undertaking further work on the electrical installation in the future. If you later vacate the property, this Certificate will demonstrate to the new owner that the minor electrical installation work carried out complied with the requirements of British Standard 7671 at the time the Certificate was issued.

PERIODIC INSPECTION REPORT NOTES:
1. This Periodic Inspection Report form shall only be used for the reporting on the condition of an existing installation.
2. The Report, normally comprising at least four pages, shall include schedules of both the inspection and the test results. Additional sheets of test results may be necessary for other than a simple installation. The page numbers of each sheet shall be indicated, together with the total number of sheets involved. The Report is only valid if a Schedule of Inspections and a Schedule of Test Results are appended.
3. The intended purpose of the Periodic Inspection Report shall be identified, together with the recipient’s details, in the appropriate boxes.
4. The maximum prospective fault current recorded should be the greater of either the short-circuit current or the earth fault current.
5. The ‘Extent and Limitations’ box shall fully identify the elements of the installation that are covered by the report and those that are not, this aspect having been agreed with the client and other interested parties before the inspection and testing is carried out.
6. The recommendation(s), if any, shall be categorised using the numbered coding 1-4 as appropriate.
7. The ‘Summary of the Inspection’ box shall clearly identify the condition of the installation in terms of safety.
8. Where the periodic inspection and testing has resulted in a satisfactory overall assessment, the time interval for the next periodic inspection and testing shall be given. The IEE Guidance Note 3 provides guidance on the maximum interval between inspections for various types of buildings. If the inspection and testing reveal that parts of the installation require urgent attention, it would be appropriate to state an earlier re-inspection date, having due regard to the degree of urgency and extent of the necessary remedial work.
9. If the space available on the model form for information on recommendations is insufficient, additional pages shall be provided as necessary.

EXTENT & LIMITATIONS OF THE INSPECTION ( note 5 ) this will come up !!!!
Extent of Electrical Installation covered by this report :
Limitations : ( see Regulation 634.2 )
This inspection has been carried out in accordance with BS-7671:2008 ( IEE Wiring Regulations ) -
Amended to Cables concealed within trunking conduit , or cables & conduits concealed under floors , in roof spaces & generally
Within the fabric of the building or underground have not been inspected ;
( EXTENT & LIMITATIONS , remember this is with the Client ) ←←←←←

PERIODIC INSPECTION REPORT GUIDANCE FOR RECIPIENTS (to be appended to the Report)
This Periodic Inspection Report form is intended for reporting on the condition of an existing electrical installation.
You should have received an original Report and the contractor should have retained a duplicate. If you were the person ordering this Report, but not the owner of the installation, you should pass this Report, or a copy of it, immediately to the owner.
The original Report is to be retained in a safe place and be shown to any person inspecting or undertaking work on the electrical installation in the future. If you later vacate the property, this Report will provide the new owner with details of the condition of the electrical installation at the time the Report was issued.
The ‘Extent and Limitations’ box should fully identify the extent of the installation covered by this Report and any limitations on the inspection and tests. The contractor should have agreed these aspects with you and with any other interested parties (Licensing Authority, Insurance Company, Building Society etc) before the inspection was carried out.
The report should identify any departures from the safety requirements of the current Regulations and any defects, damage or deterioration that affect the safety of the installation for continued use. For items classified as ‘requires urgent attention’, the safety of those using the installation may be at risk, and it is recommended that a competent person undertakes the necessary remedial work without delay.
For safety reasons, the electrical installation will need to be re-inspected at appropriate intervals by a competent person. The maximum time interval recommended before the next inspection is stated in the Report under ‘Next Inspection.’
The Report is only valid if a Schedule of Inspections and a Schedule of Test Results are appended.

Notes on the formal visual and combined inspection and test record (Form VI.2):
1 Register No - this is an individual number taken from the equipment register, for this particular item of equipment.
2 Description of equipment, e.g. lawnmower, computer monitor.
3 Construction Class - Class 0, 0I, I, II, III. Note that only Class I and II equipment may be used without special precautions being taken.
4 Equipment types - portable, movable, hand-held, stationary, fixed, built-in.
5, 6 Insert the location and any particular external influences such as heat, damp, corrosive, vibration.
7, 8 Frequency of inspection - generally as suggested in Table 7.1 of the Code of Practice for In-Service Inspection and Testing of Electrical Equipment. Inspection - items 17-23 and 28 will be completed if an inspection is being carried out. Inspection and Test - the testing in items 24v and 26 should always be preceded by inspection.
9-11 The make, model and serial number of the item of equipment should be inserted.
12-14 The voltage for which the equipment is suitable, the current consumed and the fuse rating should be inserted.
15-16 The date of purchase and the guarantee should be completed by the client
17 The date to be inserted is the date of the inspection or the date of the inspection and testing.
18 Environment and use. It should be confirmed that the equipment is suitable for use in the particular environment and is suitable for the use to which it is being put.
19 Authority is required from the user to disconnect equipment such as computers and telecom equipment - where unauthorised disconnection could result in loss of data. Authority should also be obtained if such equipment is to be subjected to the insulation resistance and electric strength tests.
20 Socket-outlet/flex outlet. The socket or flex outlet should be inspected for damage including overheating. If there are signs of overheating of the plug or socket-outlet, the socket-outlet connections should be checked as well as the plug. This work should only be carried out by an electrician.
21-23 The inspection required is described in Chapter 14 of the Code of Practice for In-Service Inspection and Testing of Electrical Equipment.
24-27 Tests. The tests are described in Chapter 15 of the Code of Practice for In-Service Inspection and Testing of Electrical Equipment. The tests should always be preceded by the Inspection items 17-23 and 28. The instrument reading is to be recorded and a tick entered if the test results are satisfactory.
28 Functional Check - a check is made to ensure that the equipment works properly.
29 Comments/other tests. Additional tests may be needed to identify a failure more clearly or other tests may be carried out such as a touch current measurement. An additional sheet may be necessary, which should be referenced in the box on this record..
30 OK to use - ‘YES’ should be inserted if the item of equipment is satisfactory for use, ‘NO’ if it is not.

 

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1. SELV – an extra-low voltage system which is electrically separated from Earth and from other systems in such a way that a single-fault cannot give rise to the risk of electric shock. The particular requirements of the Regulations must be checked (see Section 414)
2. Double or reinforced insulation. Not suitable for domestic or similar installations if it is the sole protective measure (see 412.1.3)
3. Basic protection – will include measurement of distances where appropriate
4. Obstacles – only adopted in special circumstances (see 417.2)
5. Placing out of reach – only adopted in special circumstances (see 417.3)

6. Non-conducting locations and Earth-free local equipotential bonding – these are not recognised for general application. May only be used where the installation is controlled/under the supervision of skilled or instructed persons (see Section 418)
7. Electrical separation – the particular requirements of the Regulations must be checked. If a single item of current-using equipment is supplied from a single source, see Section 413. If more than one item of current-using equipment is supplied from a single source then the installation must be controlled/under the supervision of skilled or instructed persons, see also Regulation 418.3.

FOR INSPECTION & TESTING
I/We being the person(s) responsible for the inspection & testing of the electrical installation (as indicated by my/our signatures below), particulars of which are described above, having exercised reasonable skill and care when carrying out the inspection & testing hereby CERTIFY that the work for which I/we have been responsible is to the best of my/our knowledge and belief in accordance with BS 7671:2008, amended to ..............................(date) except for the departures, if any, detailed as follows:
Details of departures from BS 7671 (Regulations 120.3 and 120.4):
The extent

FOR CONSTRUCTION
I/We being the person(s) responsible for the construction of the electrical installation (as indicated by my/our signatures below), particulars of which are de-scribed above, having exercised reasonable skill and care when carrying out the construction hereby CERTIFY that the construction work for which I/we have been responsible is to the best of my/our knowledge and belief in accordance with BS 7671:2008, amended to ................................(date) except for the departures, if any, detailed as follows:
Details of departures from BS 7671 (Regulations 120.3 and 120.4):

FOR INSPECTION & TESTING
I/We being the person(s) responsible for the inspection & testing of the electrical installation (as indicated by my/our signatures below), particulars of which are described above, having exercised reasonable skill and care when carrying out the inspection & testing hereby CERTIFY that the work for which I/we have been responsible is to the best of my/our knowledge and belief in accordance with BS 7671:2008, amended to ..............................(date) except for the departures, if any, detailed as follows:
Details of departures from BS 7671 (Regulations 120.3 and 120.4):

FOR DESIGN
I/We being the person(s) responsible for the design of the electrical installation (as indicated by my/our signatures below), particulars of which are described above, having exercised reasonable skill and care when carrying out the design hereby CERTIFY that the design work for which I/we have been responsible is to the best of my/our knowledge and belief in accordance with BS 7671:2008, amended to................................(date) except for the departures, if any, detailed as follows:
Details of departures from BS 7671 (Regulations 120.3 and 120.4):

FOR DESIGN, CONSTRUCTION, INSPECTION & TESTING
I being the person responsible for the Design, Construction, Inspection & Testing of the electrical installation (as indicated by my signature below), particulars of which are described above, having exercised reasonable skill and care when carrying out the Design, Construction, Inspection & Testing, hereby CERTIFY that the said work for which I have been responsible is to the best of my knowledge and belief in accordance with BS 7671:2008 amended to .......... (date) except for the departures, if any, detailed as follows:
Details of departures from BS 7671 (Regulations 120.3 and 120.4):

Amberleaf here , please tell you Mates about this forum : this forum is Here to help Electricians :
There’s “ NOT “ a lot of forum that is doing this , let DAN & and the Boys ← know this , many thanks Amberleaf ,
DAN your Site has the Strength & Convictions to stand up for Electricians : Big Pat on the Back ,

LEVEL 2 CERTIFICATE IN FUNDAMENTAL INSPECTION, TESTING AND INITIAL VERIFICATION OF ELECTRICAL INSTALLATIONS ( GUILDS 2392-10 )

2392
INTRODUCTION
This three day course covers the theory and practice of the fundamental inspection, testing and initial verification of electrical installations and is based on the syllabus laid down in City & Guilds' 2392-10 Scheme Regulations. Its primary objective is to prepare candidates for assessment leading, for successful candidates, to the award of a City & Guilds ‘Certificate in Fundamental Inspection, Testing and Initial Verification 2392-10'.
The course is primarily about the practical application of Part 6 of BS 7671 and participants must be familiar with much of the terminology used in the Regulations and have a good grasp of their technical requirements.
Gaining familiarity with IEE Guidance Note 3 and its content is also an important aspect of the course, and candidates will need to refer to this, and also BS 7671, during the City & Guilds practical assessment.

LEVEL 2 CERTIFICATE IN FUNDAMENTAL INSPECTION, TESTING AND INITIAL VERIFICATION OF
ELECTRICAL INSTALLATIONS

OBJECTIVES
The course embraces:
* Statutory duties and safe working practices
* BS 7671:2008 requirements for inspection, testing and certification
* IEE Guidance Note 3, Inspection & Testing, 5th edition, guidance and recommendations
* Demonstration of tests and 'hands-on' experience

By the end of the Course participants should be fully aware of:
1. The BS 7671 requirements for initial verification, inspection and testing;
2. The information required to correctly conduct the inspection and testing of a new installation;
3. The statutory and non-statutory requirements and relevant guidance material which apply to the activity of inspecting and testing of electrical installations;
4. The information to be contained on forms, i.e. Electrical Installation Certificates, Minor Works Electrical Installation Certificates and how this information should be recorded.

Participants should also be fully prepared for the practical and written assessments City & Guilds 2392-101/102:

A practical assessment (2 hours), normally conducted one week after the course completion date

A multiple-choice GOLA (Global Online Assessment) - 50 questions in 1 hour 40 minutes,

LEVEL 2 CERTIFICATE IN FUNDAMENTAL INSPECTION, TESTING AND INITIAL VERIFICATION OF
ELECTRICAL INSTALLATIONS

Module 1 Includes reference to statutory requirements and safety aspects, and also covers some of the relevant definitions of BS 7671.
Module 2 Reminds participants of some of the relevant technical requirements of other Parts of BS 7671.
Module 3 Explains the inspection requirements of BS 7671 and makes considerable reference to Guidance Note 3. It has an Inspection Assessment at the end during which the participants, are invited to identify faults by inspection. This is an important Module, since City & Guilds place considerable emphasis on inspection in both the practical and assessments in particular the filling in of the Schedule of Inspections
Module 4 Explains the sequence of tests required, dangers of testing and relevant circuit theory.
Module 5 This module covers basic care of instruments and gives candidates the opportunity to familiarise themselves with the low reading ohm-meter, the module also helps to reinforce the theory or the previous module.
Modules 6-8 Are all concerned with testing. During Modules 6 and 8 delegates receive a demonstration on 'dead' and 'live' tests on two identical Demonstration Boards.
Modules 9-11 Are all concerned with testing. During Module10 delegates receive a demonstration on 'dead' and 'live' tests on two identical Demonstration Boards.
Module 12 Covers certification and reporting. LEVEL 2 CERTIFICATE IN FUNDAMENTAL INSPECTION, TESTING AND INITIAL VERIFICATION OF ELECTRICAL INSTALLATIONS (CITY & GUILDS 2392-10) 2392

General Introduction
Module 1: Preparation for Inspection, Testing and Certification
Module 2 - BS 7671 reinforcement
Module 3 - Inspection of Installations
Module 4 - Introduction to Testing
Module 5 – Low Reading Ohm-meter
Module 6 - Testing (1) Methodology
Module 7 - Testing (1) Practical
Module 8 – Testing (2) Methodology
Module 9 - Testing (2) Practical & Fault Finding
Module 10 – Testing (3) Methodology
Module 11 – Testing (3) Practical
Module 12 - Certification and Reporting

2392-10 PS : Electricians that have NOT Done Testing for a “ Long Time “ I would “ Recommend “ that you Do the 5 DAYS COARSE , And a LOT of Studying , take it for me , its Not a Walk in the Park : If you do the 3 Day Coarse , when you come to the EXAM you head will be up your But big Time !!! Trust me one this One ,
Remember that you have three Days to take that all in : ←
Third day : your on the Boards Testing then , before you Know it doing the Exam !!!!!!!

 

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2392-10 Electricians :
Part P of the Building Regulations for England and Wales was introduced by the government in January
2005, with an aim of reducing the number of accidents in the home related to faulty electrical installations. Similar laws apply in Scotland. It is now a legal requirement for electricians, kitchen, bathroom and gas installers, and all other trades or individuals involved in carrying out domestic electrical installation work to comply with Building Regulations.

Most electrical installations carried out in a property are now notifiable: in other words the local authority
building control must be notified prior to the work being carried out. The exception is if it is carried out, inspected and certified by a person registered with a government-authorised competent person scheme such as NICEIC. Failure to comply with Part P is a
criminal offence and local authorities have the power to require the removal or alteration of work that does not comply with the regulations.

You are advised to have a property maintenance and appliance testing procedure in place. This should
ensure properties are maintained in a safe condition.
1 Carry out regular visual inspections, looking for obvious signs of damage such as scorch marks on
socket outlets and damaged cables :
2 Get the property inspected and tested by a competent person on change of occupancy, or at least every 10 years :
3 Ensure formal inspection and testing more often in higher risk properties where the installation is very old, or where damage has been found in the past
4 Carry out regular inspections on all electrical appliances
Inspection Electrical Appliances :
The Department of Trade and Industry (DTI) strongly advises estate agents, letting agents, landlords and anyone else who lets furnished accommodation to seek independent advice as to who is responsible for the safety of electrical appliances supplied in the course of business.
If you are a landlord and provide any electrical appliances (cookers, kettles, toasters, washing machines, immersion heaters, etc) as part of the tenancy, the Electrical Equipment (Safety) Regulations 1994 requires that you ensure the
appliances are safe to use when first supplied. Each time the property is relet, it will be classed as supplying to that tenant for the first time. So you need to:
Check appliances for signs of damage:
1 cuts or abrasions to the cable covering
2 cracked casing or bent pins
3 loose parts and screws
4 overheating (burn marks)
5 the outer covering of the cable not being gripped where it enters the plug or equipment. Look to
see if the coloured insulation of the internal wires is showing :
* You may need to carry out a formal inspection. It should include removal of the plug cover to check:
1 the cord grip is holding the outer part of the cable tightly :
2 the wires, including the earth wire where fitted are attached to the correct terminals :
3 no bare wire is visible other than at the terminals :
4 the terminal screws are tight
5 there is no sign of internal damage, overheating or entry of liquid, dust or dirt Most of these checks apply to extension leads and their plugs and sockets. But some faults cannot be detected in this way, such as lack of continuous earths, which for some equipment, is essential for safety. All earthed equipment should have an occasional combined inspection and test to look for faults. Combined inspection and testing should be
carried out where there is reason to suspect the equipment may be faulty or damaged or
contaminated, but where this cannot be confirmed by visual inspection. Combined testing should also be
carried out after any repair or similar work to the equipment :
Extension Leads Warning :
Use of extension leads should be avoided where possible. If used, they should be tested as portable
appliances. It is recommended that 3-core leads ( including a protective earthing conductor) be used.
A standard 13 amp, 3-pin extension socket outlet with a 2-core cable should never be used even if the
appliance is Class II (music system, TV and video), as it would not provide protection against electric shock
if used at any time with an item of Class I ( cookers, washing machines, refrigerators, irons, dishwashers ).
Portable Equipment Outdoors :
In domestic premises, all socket outlets, which may be used for portable equipment outdoors, should be
protected by an RCD (a safety device that switches off the electricity automatically when it detects an
earth fault) to provide protection against electric shock . Socket outlets installed below kitchen worktops may
usually be considered to be unavailable for connection of outdoor portable equipment, and
would therefore not be required to be RCD protected. It is wise to exclude socket outlets intended for refrigerators and freezers from circuits which require sensitive RCD protection .
Contractors are assessed against the national standard for the safety of electrical installations,
British Standard BS 7671: Requirements for electrical installations (also known as the IEE Wiring Regulations). They must also comply with the electrical safety requirements of any other applicable Codes of Practice, such as those for fire alarms, emergency lighting. In England and Wales, it is a legal requirement for electrical work carried out in and outside the home to comply with Part P of the Building Regulations.

2392-10 Domestic Electrician : ↑↑↑↑ If you are a landlord, you need to be sure that the electrics in your property or properties are safe. That’s the law.
Dozens of people die and thousands are injured every year through unsafe electrics. If you let property, take note of these statistics – rented properties are potentially more at risk than owner-occupier homes as they tend to get more
wear and tear. Identifying faulty electrical installations can be difficult. Especially in rented properties as tenants
may have carried out electrical work themselves without requesting permission or notifying their landlord. An accident could be waiting to happen, and the electrical installation in one of your houses or flats may not comply with national safety standards and Building Regulations.
( IF your got to send a Note to a Landlord , here it is ) your “ But “ is Covered :

Apprentice Question 1 :
Assessment of general characteristics would not include :
Choose one answer.
(A) Purpose for which the installation is intended to be used
(B) External influences
(C) Length of final circuit cable runs *
(D) Compatibility of equipment
Question 2 :
Where the provision of safety services is required the supply characteristics for the safety services or systems shall be:
Choose one answer.
(A) AC only
(B) Separately assessed *
(c) DC only
(D) Exactly the same as the incoming supply characteristics
Question 3
Characteristics of supply shall be determined by:
Choose one answer.
(A) Inspection
(B) Measurement
(C) Enquiry and calculation
(D) Calculation, measurement, enquiry or inspection *

Question 4 :
When determining maximum demand of an installation:
(A) All circuit breakers and fuse ratings within the installation must be added together
(B) All circuits must be fully loaded
(C) A clip on ammeter must be used during low demand periods
(D. Diversity may be taken into account *
Question 5 :
Every installation shall be divided into circuits as necessary in order to:
(A) Reduce running costs
(B) Reduce final circuit cable lengths
(C) Facilitate inspection and testing and maintenance *
(D) Minimise installation time
Question 6 :
Assessment of general characteristics would include:
(A) Maintainability, safety services and continuity of service *

(B) Cost of installation
(C) Number of distribution boards and or consumer units
(D) Total floor area

 

[amberleaf]

17th Edition Forms :
1 Initial inspection and testing

Forms 1 to 4 are designed for use when inspecting and testing a new installation, or an alteration or addition to an existing installation. The forms comprise the following:
1 Short form of Electrical Installation Certificate (To be used when one person is responsible for the design, construction, inspection and testing of an installation.)

2 Electrical Installation Certificate (Standard form from Appendix 6 of BS 7671)
3 Schedule of Inspections
4 Schedule of Test Results.
Notes on completion and guidance for recipients are provided with the form.

2 Minor works :
The complete set of forms for initial inspection and testing may not be appropriate for minor works. When an addition to an electrical installation does not extend to the installation of a new circuit, the minor works form may be used. This form is intended for such work as the addition of a socket-outlet or lighting point to an existing circuit, or for repair or modification.
Form 5 is the Minor Electrical Installation Works Certificate from Appendix 6 of BS 7671.
Notes on completion and guidance for recipients are provided with the form.

3 Periodic inspection :
Form 6, the Periodic Inspection Report from Appendix 6 of BS 7671, is for use when carrying out routine periodic inspection and testing of an existing installation. It is not for use when alterations or additions are made. A Schedule of Inspections (3) and Schedule of Test Results (4) should accompany the Periodic Inspection Report (6).
Notes on completion and guidance for recipients are provided with the form.

Electrical Protection : Apprentices ,
“ Isolation and Cutting Off Supply “
(a) Does every machine have a means of isolation provided and is it accessible ?
(b) Does every machine have a means by which it can be stopped, e.g. a stop button and is this button of the mushroom head type and easily accessible?
(c) Are isolators in good condition and can the be operated without difficulty? For example, check for broken handles or any impediment in the operation?
(d) Is the system provided with adequate means of isolation back at the mains switchroom and at the respective distribution points? Does every machine have a means of isolation?
(e) Are all the isolation points clearly marked for the circuits they control? Identification is very important and should be looked for in every inspection. This should also include identification of fuse ways within distribution boards and at front and rear of switchboards.
(f) Check to ensure that all circuits have a means of switching off, e.g. lighting and fan switches and are these in good working order and not broken ?
(g) Ask about OFF LOAD isolation and the procedures existing for operation of such...
who does it and by which methods ?
“ Earthing “
Note: visual examinations of the earthing arrangements.
(a) All conductive parts, i.e. metallic enclosures, pipes, radiators, taps etc., must be bonded and efficiently connected to earth.
(b) Check this carefully and if the earthing protective conductor is visible, examine the connections for tightness. They must be as tight as possible, because loose or slack connections give a high resistance and result in danger.
(c) Check colour coding of the earthing protective conductor; this should be green/yellow. 514.3 / 514.4.2
(d) Is the conductor large enough to carry fault currents without destruction ?
(e) How often is the EARTH FAULT IMPEDANCE tested and what are the latest results ?
(f) Is armouring, conduit or trunking used as the earth protective conductor? Check glands for tightness, look for signs of corrosion and damage ,
(g) Ask about the earthing system... do they obtain this from the Supply Authority and how, or do they have an earth rod or a water pipe ? 411.3.1.2
“ Portable Tools “
Note 1: The safest voltage is the lowest practicable voltage. Generally the recommended voltage is 110 volts AC from a step down transformer where the mid point of the secondary 110 volt winding is connected to earth ( CTE ). This limits the shock to earth voltage to 55 volts AC. In confined conducting locations the voltage should be much lower than this, i.e. no more than 50 volts from an unearthed ( or isolated earth ) supply, or 50 volts from a ( CTE ) supply to give a 25 volt shock-earth.
(b) Check the cables and entries, are they damaged?
(c) Are there any taped joints. If so have them replaced ,
(d) Check to see if the metal casing or any other metallic parts of the tool are sufficiently earthed.
Note 2: Double insulated or all insulated (Class II) tools do not require an earth. It is therefore vitally
important to ensure that the casing, cable insulation and plug are not damaged.
(e) If the tool has to be supplied from a 230 volt AC supply ask for RCD (30mA trip) protection.
(f) Are they inspected, tested and maintained regularly ?
(g) Check plugs, fuses, cables and general conditions .
“ Adverse Environmental Conditions “
(a) Firstly, check the environment, i.e. is it:
• Dusty.
• Wet or damp (do they use hosing down operations).
• Corrosive.
• Dirty.
• Adverse weather or just simple weather exposure.
• High temperatures and/or pressures.
• Flammable or explosive atmospheres.
Note: Standard electrical equipment will be seriously affected by these conditions and danger will result. Electrical equipment will have to be selected accordingly to suit the environment so as to combat the consequential problems. There are many British Standards dealing with the requirements for electrical equipment in adverse atmospheres and these should be consulted along with specialist advice.
(b) Check the type of installed equipment against the environment and advise accordingly:
• Dirty, dusty, wet, adverse weather – BS-EN60529.
• Flammable/Explosive areas – BS-EN60079.
• Corrosion – Replace or clean down and repaint with anti-corrosive paint.
• High temperature, pressures – Reposition or replace with suitable equipment.
(c) Check also the installation medium such as cables, conduits etc. It is better to use armoured cables or MICC cables in most environments.

2392-10 Traditional Junction Boxes : ( Regulation 526.3 p-106 : BS-EN60670-22 – BS 6220
unless using a solution such as maintenance free terminals, the access to electrical connections should be
adequate for their safe and proper inspection, testing and maintenance. In this respect, connections should be in a location where they can reasonably be reached and where there is adequate working space.:

Where connections are made in roof spaces and inter-floor spaces the enclosures containing the connections should normally be fixed and provision must be made for their access. Providing these two constraints are complied with, then the
continued use of standard circular junction boxes remains acceptable.

Maintenance Free Connections
Maintenance free terminals provide one solution where accessibility is an issue :

Junction boxes are commonly used during alterations and additions to an installation. With certain exceptions regulation 526.3 requires that every connection shall be accessible for inspection, testing and maintenance.
The Electrical Safety Council Technical Manual states that “a junction box with screw terminals is an example of where connections must be accessible”. The reason is to allow inspection of joints which could have relaxed or loosened over time, a recognised problem with screwed terminals.
Unless provision is made for access, where boarding, carpet or other similar covering is laid over a junction box with screw terminals, it may not be considered accessible and maintenance free terminals should be used.
This is further reinforced in Appendix 15 of the Wiring Regulations which states “Junction boxes with screw terminals must be
accessible for inspection, testing & maintenance or, alternatively, use maintenance-free terminals / connection (Regulation 526.3)”

Junction boxes with screw terminals must be accessible for inspection...

 

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SCHEDULES ******
The attached Schedules are part of this document and this Certificate is valid only when they are attached to it.
............ Schedules of Inspections and ............ Schedules of Test Results are attached. (Enter quantities of schedules attached).

( C&G 2392-10 ) ( 2 days plus 1 day Assessments )
This new qualification has been developed in order to meet the needs of the electrical contracting industry.
It is intended to provide candidates with an introduction to the fundamentals of inspection, testing and initial verification of electrical installations.
It is aimed at practicing electricians who have not carried out inspection and testing since qualifying or who require some update training.
It is also suitable for those coming into the industry with limited experience of inspection and testing.
Candidates who achieve this qualification could progress onto the Certificate in Inspection, Testing and Certification of Electrical Installations (2391-10).

SCHEDULE OF TEST RESULTS

NOTES ON SCHEDULE OF TEST RESULTS :
Type of supply is ascertained from the distributor or by inspection :
( Ze at origin.) When the maximum value declared by the distributor is used, the effectiveness of the earth must be confirmed
Prospective fault current (PFC). The value recorded is the greater of either the short-circuit current or the earth fault current
Preferably determined by enquiry of the distributor

Short-circuit capacity of the device is noted, see Table 7.2A of the On-Site Guide or Table 2.4 of GN3

the following tests, where relevant, shall be carried out in the following sequence :
Continuity of protective conductors, including main and supplementary bonding
Every protective conductor, including main and supplementary bonding conductors, should be tested to verify that it is continuous and correctly connected :

Continuity :
Where Test Method 1 is used, enter the measured resistance of the line conductor plus the circuit protective conductor ( R1 + R2 )
See 10.3.1 of the On-Site Guide or 2.7.5 of GN3, During the continuity testing (Test Method 1) the following polarity checks are to be carried out:
(a) every fuse and single-pole control and protective device is connected in the line conductor only
(b) centre-contact bayonet and Edison screw lampholders have outer contact connected to the neutral conductor
c) wiring is correctly connected to socket-outlets and similar accessories. Compliance is to be indicated by a tick in polarity column 11
(R1 + R2 ) need not be recorded if ( R2 is recorded in column 7 :


Where Test Method 2 is used, the maximum value of ( R2 ) is recorded in column 7.
See 10.3.1 of the On-Site Guide or 2.7.5 of GN3

Continuity of ring final circuit conductors :
A test shall be made to verify the continuity of each conductor including the protective conductor of every ring final circuit
See 10.3.2 : of the On-Site Guide or 2.7.6 of GN3 :

Insulation Resistance
All voltage sensitive devices to be disconnected or test between live conductors (line and neutral) connected together and earth
The insulation resistance between live conductors is to be inserted in column 9
The minimum insulation resistance values are given in Table 10.1 of the On-Site Guide or Table 2.2 of GN3
See 10.3.3 (iv) of the On-Site Guide or 2.7.7 of GN3

All the preceding tests should be carried out before the installation is energised :
Polarity :
A satisfactory polarity test may be indicated by a tick in column 11
Only in a Schedule of Test Results associated with a Periodic Inspection Report is it acceptable to record incorrect polarity ,

Earth fault loop impedance Z
This may be determined either by direct measurement at the furthest point of a live circuit or by adding (R1 + R2 ) of column 6 to
Ze . is determined by measurement at the origin of the installation or preferably the value declared by the supply company used
Zs = Ze + ( R1 + R2 ) Zs should be less than the values given in Appendix 2 of the On-Site Guide or Appx 2 of GN3

functional testing :
The operation of RCDs (including RCBOs) shall be tested by simulating a fault condition, independent of any test facility in the device
Record operating time in column 13. Effectiveness of the test button must be confirmed
See Section 11 of the On-Site Guide or 2.7.15 and 2.7.18 of GN3

All switchgear and controlgear assemblies, drives, control and interlocks, etc must be operated to ensure that they are properly
mounted, adjusted, and installed Satisfactory operation is indicated by a tick in column 14
Earth electrode resistance
The earth electrode resistance of TT installations must be measured, and normally an RCD is required
For reliability in service the resistance of any earth electrode should be below 200 Ω. Record the value on Form 1, 2 or 6, as
appropriate. See 10.3.5 of the On-Site Guide or 2.7.12 of GN-3

NOTES ON COMPLETION OF MINOR ELECTRICAL INSTALLATION WORKS CERTIFICATE

Scope
The Minor Works Certificate is intended to be used for additions and alterations to an installation that do not
extend to the provision of a new circuit. Examples include the addition of socket-outlets or lighting points to
an existing circuit, the relocation of a light switch etc. This Certificate may also be used for the
replacement of equipment such as accessories or luminaires, but not for the replacement of
distribution boards or similar items. Appropriate inspection and testing, however, should always be carried out irrespective of the extent of the work undertaken ,

Part 1 Description of minor works :

1,2 : The minor works must be so described that the work that is the subject of the certification can be readily identified.
4 See Regulations 120.3 and 120.4. No departures are to be expected except in most unusual circumstances. See also Regulation 633.1

Part 2 Installation details :
2 : The method of fault protection must be clearly identified e.g. earthed equipotential bonding and automatic disconnection of supply using fuse/circuit-breaker/RCD.
4 : If the existing installation lacks either an effective means of earthing or adequate main equipotential bonding conductors, this must be clearly stated. See Regulation 633.2
Recorded departures from BS-7671 may constitute non-compliance with the Electricity Safety, quality and continuity Regulations 2002 (as amended) or the Electricity at Work Regulations 1989. It is important that the client is advised immediately in writing.
Part 3 Essential Tests :
The relevant provisions of Part 6 ( Inspection and Testing ) of BS 7671 must be applied in full to all minor
works. For example, where a socket-outlet is added to an existing circuit it is necessary to:
1 : establish that the earthing contact of the socket-outlet is connected to the main earthing terminal
2 : measure the insulation resistance of the circuit that has been added to, and establish that it complies with Table 61 of BS 7671
3 : measure the earth fault loop impedance to establish that the maximum permitted disconnection time is not exceeded
4 : check that the polarity of the socket-outlet is correct
5 : (if the work is protected by an RCD) verify the effectiveness of the RCD
Part 4 Declaration :
1.3 : The Certificate shall be made out and signed by a competent person in respect of the design construction, inspection and testing of the work.
1,3 The competent person will have a sound knowledge and experience relevant to the nature of the
work undertaken and to the technical standards set down in BS-7671 be fully versed in the inspection
and testing procedures contained in the Regulations and employ adequate testing equipment.
2 : When making out and signing a form on behalf of a company or other business entity, individuals shall state for whom they are acting.

 

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About the Electrical Testing and Inspection
During the inspection, you can rest assured that we will cover the most obvious danger points and those that are less obvious, including:
• System types
• Live conductors
• Nature of supply parameters
• Supply protective device characteristics
• Means of earthing
• Details of installation earth electrode
• Main switch circuit breaker
• Main protective conductors
• Bonding of extraneous conductive parts
• Method of protection against indirect contact
• Method of protection against electrical shock
• Prevention of mutual detrimental influence
• Protection against indirect contact
• Cables and conductors
• Circuits
• Boards
Emergency Lighting Testing BS 5266
Emergency lighting is required in all premises where people are employed and it is a mandatory requirement to be installed where artificial lighting is installed.

Under the “Fire Precaution (Workplace) Regulations 1999” all Employers, Landlords or Occupiers have a duty to carry out a risk assessment to ensure their premises and activities are able to facilitate safe escape in the event of an emergency.
The Emergency Lighting British Standard BS5266 defines the requirements for the correct installation of Emergency Lighting. Compliance with this standard will ensure that your premises, meets the requirements of the Fire Precaution (Workplace) Regulations.

BS5266 requires inspection & tests should be carried out at the following intervals (Frequencies);

Daily
Monthly
Six-Monthly
Three Yearly
Subsequent Annual Test

Portable Appliance ( Pat Testing )
The law clearly states that all employers have a legal obligation to maintain all electrical equipment in order to ensure a safe working environment. This includes all electrically operated items such as computers, printers, photocopiers, kettles, extension leads, vacuums etc.
Organisations of all types and sizes have a duty to protect their employees and business from this risk and to comply with the Electricity at Work Regulations 1989, Health and Safety at Work Act 1974, The Electrical Equipment (Safety) Regulations 1994, Provision and Use of Work Equipment Regulations 1998
• Replacement of faulty or damaged mains plug (BS1363/A)
• Replacement of damaged or incorrectly rated fuses (BS1362)
• Re-wiring of incorrect connections in the mains plug BS1363/A)
• Repair to faulty cable grips in the mains plug BS1363/A)
• Minor repairs requiring less than ten minutes labour
• Re-test following repair

All Appliances are labelled with the result of the test (pass or fail).

Description of Minor Works :

The minor works must be so described that the work that is the subject of the certification can be readily identified.
See Regulations 120.3 ) This Standard sets out Technical Requirements intended to ensure that Electrical Installations conform to
The Fundamental Principles chapter 13 : as follows , ( Part 3 ) ( Part 4 ) ( Part 5 ) ( Part 6 ) ** ( Part 7 ) ** and 120.4. No departures are to be expected except in most unusual circumstances. See also Regulation 633.1 ,
633.1 : Additions & Alterations , this Requirement of Sections 631 & 632 for the issue of an Electrical Installation Certificate or a
Minor Electrical Installation Works Certificate shall apply to all the work of the Additions or Alterations ,

 

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“ Operation of Overload and Fault Current Devices “

When a fault is noticed , it is usually because a circuit or piece of equipment has stopped working and this is usually because the protective device has done its job and operated , the rating of a protective device should be greater than , or at least equal to , the rating of the circuit or equipment it is protecting , e.g. 10 x 100 watt lamps equate to a total current use of 4.35 amperes ,
Therefore a device rated at 5 or 6 amperes could protect this circuit ,
A portable domestic appliance which has a label rating of 2.7kW equates to a total current of 11.74 amperes ,
Therefore a fuse rated at 13 amperes should be fitted in the plug ,
Protective devices are designed to operate when an excess of current ( greater than the design current of the circuit )
Passes through it , the fault currents excess heat can cause a fuse element to rupture or the device mechanism to trip ,
Dependent on which type of device is installed , these currents may not necessarily be circuit faults , but short-lived overloads specific to a piece of equipment or outlet , the regulations categorise these as overload current & overcurrent , For conductors ,
The rated value is the current-carrying capacity , most excess currents are , however , due to faults , either earth faults or short circuit type which cause excessive currents , whichever type of fault occurs the designer should take account of its effect on the installation wiring and choose a suitable device to disconnect the fault quickly and safely , the fundamental effect of any fault is a rise in current and therefore a rise in temperature , high temperature destroys the properties of installation , which in itself could lead to a short circuit , high currents damage equipment , and earth fault currents are dangerous to the body from electric shock ,
“ Overloads faults “
Adaptors used in socket outlets exceeding the rated load of circuit :
Extra load being added to an existing circuit or installation :
Not accounting for starting current on a motor circuit :
“ Short circuit faults “
Insulation breakdown :
Severing of live circuit conductors :
Wrong termination of conductors energised before being tested :
“ Earth faults “
Insulation breakdown :
Incorrect polarity :
Poor termination of conductors :
“ fuse holder has melted due to overloading “
“ wrong type of starter in fluorescent tube has melted due to excess power demand “
“ poor termination of ( CPC ) circuit protective conductors “ in junction boxes “

Definitions :
“ Overloads current “ – an overcurrent occurring in a circuit which is electrically sound :
“ Overcurrent ” – a current exceeding the rated value
“ Earth fault current “ – a fault current which flows to earth :
“ Short circuit current “ – an overcurent resulting from a fault of negligible impedance between live conductors :

 

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“ Basic electricity “ Apprentice :
All questions about the nature of electricity lead to the composition of matter. All matter is made up of atoms.
Every atom has a nucleus, with positively - charged protons, and neutrons with no charge.
Moving around the nucleus are negatively -charged electrons.
With equal numbers of protons and electrons, their charges cancel each other out, leaving the atom with no overall charge.
An excess of electrons gives an atom a negative charge; a deficiency gives it a positive charge.
In some materials, there are electrons called free electrons, only loosely held by the nucleus.
The more free electrons a material has, the better it can conduct electricity.
Metals typically have lots of free electrons and are good conductors.
In insulators, electrons are bound much more tightly to the nucleus.
They cannot easily move freely, so they are not readily available for electric current.
Semiconductors conduct electricity more easily than insulators but not as well as conductors. They are crucial in electronics

Free electrons

Free electrons are necessary for electric current, but for those electrons to move, they need a complete pathway, or circuit, and there must be a force to make them move. The force from a battery sets free electrons moving.
Like charges repel, so the negative electrons are repelled from the negative terminal. Unlike charges attract, so the electrons are also attracted towards the positive terminal.
They flow in one direction only. This is called direct current or DC. Most circuits in motor vehicles use direct current.
The larger the charge at the positive terminal, the more strongly it attracts free electrons. This attraction acts as a force driving the electrons along. The greater the force, the stronger the electrical current. The force is called electromotive force or EMF. It’s also known as "voltage".
Also affecting the current flow in a circuit is electrical resistance, measured in ohms. All materials have resistance - even good conductors.
Four factors determine the level of resistance:
• Type of material - whether it has enough free electrons;
• Length of the conductor - as length increases, so does resistance;
• Size of the conductor - the larger the conductor, the greater the amount of current it can carry; and
• Temperature of the conductor.
The higher the temperature, the harder it is for electrons to pass through it and the higher the resistance. While all materials have some resistance to current flow, a resistor is a component designed to cause a particular voltage drop in a circuit. It has a set resistance, usually marked or coded on its surface.
Since electric current is the flow of electrons, it's natural to say the direction of current is the direction in which electrons move. However, before the discovery that electric current was the flow of electrons, it was thought the natural way for electricity to move was from positive to negative.
Both concepts are still in use. Current said to flow from positive to negative, is called conventional current. Current said to flow from negative to positive, is called electron current.

Resistance
Electrical resistance is a measure of the degree to which an object opposes the passage of an electric current. The SI unit of electrical resistance is the ohm. Its reciprocal quantity is electrical conductance measured
Resistance is defined as the ratio of the potential difference (i.e. voltage) across the object (such as a resistor) to the current passing through it:
R = V / I
where
• R is the resistance of the object
• V the potential difference across the object, measured in volts
• I is the current passing through the object, measured in amperes
For a wide variety of materials and conditions, the electrical resistance does not depend on the amount of current flowing or the amount of applied voltage. This means that voltage is proportional to current and the proportionality constant is the electrical resistance. This case is described by Ohm's law and such materials are described as ohmic. V can either be measured directly across the object or calculated from a subtraction of voltages relative to a reference point. The former method is simpler for a single object and is likely to be more accurate. There may also be problems with the latter method if the voltage supply is AC and the two measurements from the reference point are not in phase with each other.

Electromagnetic induction

When a conductor cuts across a magnetic field, current flows in the conductor. It flows one way when the conductor cuts the field in one direction, then reverses as it cuts the field in the opposite direction.
The current is called alternating, because it flows one way, and then the other. The term alternating current is often shortened to AC. That's the sort of electrical energy that comes through power outlets. It's also produced by an alternator, as the name indicates.
Moving a wire inside a magnetic field produces a current flow. Similarly, moving a magnet inside a stationary coil of wire, produces the same effect.
If a magnet is rotating in an iron yoke, and a coil of wire is wound around the stem of the yoke to form a complete circuit with the ammeter, this will indicate if current flows.
As the magnet rotates, the ammeter deflects for current flow. For every half-revolution, current flow reverses. Increasing the speed of the magnet increases the amount of electrical energy produced. Electromagnetic induction is applied in alternators and ignition coils.
Electromagnetic induction is the production of an electrical potential difference (or voltage) across a conductor situated in a changing magnetic flux.
Michael Faraday is generally credited with having discovered the induction phenomenon in 1831 though it may have been anticipated by the work of Francesco Zantedeschi in 1829. Faraday found that the electromotive force (EMF) produced along a closed path is proportional to the rate of change of the magnetic flux through any surface bounded by that path. In practice, this means that an electrical current will flow in any closed conductor, when the magnetic flux through a surface bounded by the conductor changes. This applies whether the field itself changes in strength or the conductor is moved through it. Electromagnetic induction underlies the operation of generators, induction motors, transformers, and most other electrical machines.

Electromagnetism
Electromagnetism is the physics of the electromagnetic field: a field, encompassing all of space, composed of the electric field and the magnetic field. The electric field can be produced by stationary electric charges, and gives rise to the electric force, which causes static electricity and drives the flow of electric current in electrical conductors. The magnetic field can be produced by the motion of electric charges, such as an electric current flowing along a wire, and gives rise to the magnetic force one associates with magnets. The term "electromagnetism" comes from the fact that the electric and magnetic fields are closely intertwined, and, under many circumstances, it is impossible to consider the two separately. For instance, a changing magnetic field gives rise to an electric field; this is the phenomenon of electromagnetic induction, which underlies the operation of electrical generators, induction motors, and transformers. The term electrodynamics is sometimes used to refer to the combination of electromagnetism with mechanics. This subject deals with the effects of the electromagnetic field on the mechanical behavior of electrically charged particles.

Electromagnetic force
The force that the electromagnetic field exerts on electrically charged particles, called the electromagnetic force, is one of the four fundamental forces. The other fundamental forces are the strong nuclear force (which holds atomic nuclei together), the weak nuclear force (which causes certain forms of radioactive decay), and the gravitational force. All other forces are ultimately derived from these fundamental forces. However, it turns out that the electromagnetic force is the one responsible for practically all the phenomena one encounters in daily life, with the exception of gravity. Roughly speaking, all the forces involved in interactions between atoms can be traced to the electromagnetic force acting on the electrically charged protons and electrons inside the atoms. This includes the forces we experience in "pushing" or "pulling" ordinary material objects, which come from the intermolecular forces between the individual molecules in our bodies and those in the objects. It also includes all forms of chemical phenomena, which arise from interactions between electron orbital’s.

 

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Electrical power

Energy is the potential to do work. But work is done only when the energy is released.
A disconnected battery isn't doing work, but it has the potential to do work, so it's a source of energy.
The difference in electron supply at the battery terminals is sometimes called the potential difference - in the case of a standard charged automotive battery, a potential of 12 volts. Tapping this potential means turning one form of energy, the battery's electrochemical energy, into another.
Turning one form of energy into another is called work.
The amount of energy transformed is the amount of work done. When a person's legs turn the pedals of a bicycle, physical energy is being turned into mechanical energy. A power drill turns electrical energy into mechanical energy.
In each case, work is being done, but the power drill is different - it does the work quicker, delivering more mechanical energy. That difference is called Power. Power is the rate at which work is done. The rate of transforming energy. In an electrical circuit, power refers to the rate at which electrical energy is transformed into another kind of energy
The unit of power is the watt. 1 watt is produced when 1 volt causes a current flow of 1 amp. From this comes the power equation: P, the power in watts, equals V, the voltage in volts, multiplied by I, the current in amps.
This calculation is applied just like Ohm's law.
When current flows in a circuit with a resistor in it, the resistor may become hot as it converts electrical energy into heat energy. If this circuit is powered by a 12 volt battery with a current of 2 amps, using the power equation (P=VxI), we can determine that 24 watts of power are being taken from the circuit by the resistor
It is also possible to simplify and transpose the power equation:
• Power equals voltage times current
• Therefore, voltage equals power divided by current
• and current equals power divided by voltage.

Instantaneous electrical power
The instantaneous electrical power P delivered to a component is defined as:
P = I x V where
• P is the instantaneous power, measured in watts
• V is the potential difference (or voltage drop) across the component, measured in volts
• I is the current flowing through it, measured in amperes
If the component is a resistor, then:
P = I2 x R or
P = V2 ÷ R
where
R is the resistance, measured in ohm.

Parallel circuits

In a series circuit, components are connected like links in a chain. If any link fails, current to all the components is cut off.
In a parallel circuit, all components are connected directly to the voltage supply. If any connection or component fails in a parallel circuit, current continues to flow through the rest.
This is one reason why parallel circuits are used in automotive applications like lighting systems. If one lamp fails, current continues to flow through the rest. In a series circuit, all would go out, which could be disastrous.
Also, since all components connect directly to the battery terminals, the metal of the vehicle’s body can become one of the conductors. One terminal of the battery, and one of each component, can be connected anywhere on the body or chassis, to complete the circuit. This is called an earth, or ground connection. It saves a lot of connecting wire.
A feature of a parallel circuit is that the voltage across each component is the same as battery voltage.
No matter how many components are added, or removed, as long as they’re in parallel, the voltage across them will be the same as across each other component, including the battery.
Another feature of a parallel circuit is that the current flowing in each branch is determined by the resistance of that branch.
In a parallel circuit where the resistors in each branch are the same, the current flowing in each branch is therefore also the same. However, the sum of their individual currents is equal to the total current flowing in the circuit.
When the resistance's are not equal, then the current divides in accordance with the value of each resistance, but the total current flow is still the sum of the currents flowing in each branch.

Parallel circuit resistance Say you have a 12 volt parallel circuit with three branches, each with a 12 ohm resistor, and a current flow of 3 amperes. If you add another 12 ohm resistor to the circuit it produces an effect which is the opposite of what might be expected. Current increases from 3 amperes to 4.

This is because, in a parallel circuit, adding more branches provides more pathways, but decreases the overall circuit resistance, so current flow increases.

Total resistance of a parallel circuit is found by turning all the resistances upside down, to make fractions called reciprocals. In this case, each 12 becomes 1/12th.

The 4/12ths are added together, and the answer turned back up the way it was, so that it is 12/4, or 12 divided by 4, which equals 3. 3 ohms is therefore the total resistance in the circuit. Ohm’s law confirms the ammeter reading of 4 amperes. Now, if 2 resistors are removed, what is the result?

1/12th plus 1/12th is 2/12th’s, which, turned back the way it was, is 12 over 2, or 6 ohms. Voltage across the components is still 12 volts, but by Ohm’s law, the new current is 2 amperes. So removing the resistors, in this circuit, halves the current.

Wire sizing Wire size is very important for the correct operation of electrical circuits. Selecting too small a gauge wire for an application will adversely effect the operation of the circuit. This will cause voltage drop and poor performance, or, in extreme cases, the cable will get hot enough to melt the insulation. Selecting too large a gauge increases costs and weight.

The resistance of a cable affects how much current it can carry. The resistance of a cable is determined by its length and its diameter.

The longer the cable and the smaller the diameter, the higher the resistance. The shorter the cable and the larger the diameter the lower the resistance.

To select the correct cable gauge for any given application it is best to refer to a cable chart. Manufacturers and standards bodies use cable gauge charts to define how much current each cable gauge can carry safely and effectively.

Over the years a number of different wire gauges have been used to determine application.

The primary wire gauges are the metric wire gauge and the American wire gauge or AWG.

For example, this 12 Volt circuit is designed for a maximum current flow of 10 Amps. Because of the installation design, the length of the cable used to wire the circuit needs to be approximately 20 feet or 7 meters in length, so using the AWG table as a reference we see that the correct gauge cable to use is 16AWG.

 

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GUIDANCE FOR RECIPIENTS
This safety Certificate has been issued to confirm that the electrical installation work to which it relates has been designed, constructed, inspected and tested in accordance with British Standard 7671 (the IEE Wiring Regulations).
You should have received an "original" Certificate and the contractor should have retained a duplicate. If you were the person ordering the work, but not the owner of the installation, you should pass this Certificate, or a full copy of it including the schedules, immediately to the owner.
The Certificate should be retained in a safe place and be shown to any person inspecting or undertaking further work on the electrical installation in the future. If you later vacate the property, this Certificate will demonstrate to the new owner that the electrical installation complied with the requirements of British Standard 7671 at the time the Certificate was issued. The Construction (Design and Management) Regulations require that for a project covered by those Regulations, a copy of this Certificate, together with schedules is included in the project health and safety documentation.
For safety reasons, the electrical installation will need to be inspected at appropriate intervals by a competent person. The maximum time interval recommended before the next inspection is stated on Page 1 under "Next Inspection".
This Certificate is intended to be issued only for a new electrical installation or for new work associated with an addition or alteration or to an existing installation. It should not have been issued for the inspection of an existing electrical installation. A "Periodic Inspection Report" should be issued for such an inspection.
The Certificate is only valid if a Schedule of Inspections and Schedule of Test Results are appended.

Why must we have earth electrodes
The principle of earthing is to consider the general mass of earth as a reference (zero) potential. Thus, everything connected directly to it will be at this zero potential, or above it by the amount of the volt drop in the connection system (for example, the volt drop in a protective conductor carrying fault current). The purpose of the earth electrode is to connect to the general mass of earth.
With the increasing use of underground supplies and of protective multiple earthing (PME) it is becoming more common for the consumer to be provided with an earth terminal rather than having to make contact with earth using an earth electrode.
The tester : The person who carries out the test and inspection must be competent to do so, and must be able to ensure his own safety, as well as that of others in the vicinity. It follows that he must be skilled and have experience of the type of installation to be inspected and tested so that there will be no accidents during the process to people, to livestock, or to property. The Regulations do not define the term 'competent', but it should be taken to mean a qualified electrician or electrical engineer.
Why do we need inspection and testing
There is little point in setting up Regulations to control the way in which electrical installations are designed and installed if it is not verified that they have been followed. the protection of installation users against the danger of fatal electric shock due to indirect contact is usually the low impedance of the earth-fault loop; unless this impedance is correctly measured. this safety cannot be confirmed. in this case the test cannot be carried out during installation, because part of the loop is made up of the supply system which is not connected until work is complete. In the event of an open circuit in a protective conductor, the whole of the earthed system could become live during the earth-fault loop test. The correct sequence of testing would prevent such a danger, but the tester must always be aware of the hazards applying to himself and to others due to his activities. Testing routines must take account of the dangers and be arranged to prevent them. Prominent notices should be displayed to indicate that no attempt should be made to use the installation whilst testing is in progress.
The precautions to be taken by the tester should include the following:
1. -make sure that all safety precautions are observed
2. - have a clear understanding of the installation, how it is designed and how it has been installed
3. - make sure that the instruments to be used for the tests are to the necessary standards ,
4. - check that the test leads to be used are in good order, with no cracked or broken insulation or connectors, and are fused where necessary to comply with the Health and Safety Executive Guidance Note GS38
5. - be aware of the dangers associated with the use of high voltages for insulation testing. For example, cables or capacitors connected in a circuit which has been insulation tested may have become charged to a high potential and may hold it for a significant time. ←←←

Essential Tests :
continuity of protective conductors : satisfactory ( GN-3 )

Insulation resistance:
Phase/neutral…………………………MΩ
Phase/earth …………………………MΩ
Neutral/earth …………………………MΩ
Earth fault loop impedance ………………………… Ω ( Live Test )

Polarity satisfactory

RCD operation (if applicable). Rated residual operating current I∆n ………mA and operating time of ………mS (at I∆n

Notes on the formal visual and combined inspection and test record ( Form VI.2 )

1, Register No - this is an individual number taken from the equipment register, for this particular item of equipment
2, Description of equipment, e.g. lawnmower, computer monitor
3, Construction Class - Class 0, 0I, I, II, III. Note that only Class I and II equipment may be used without special precautions being taken
4, Equipment types - portable, movable, hand-held, stationary, fixed, built-in
5/6 , Insert the location and any particular external influences such as heat, damp, corrosive, vibration.
Frequency of inspection - generally as suggested in Table 7.1 of the Code of Practice for In-Service Inspection and Testing of Electrical Equipment
Inspection - items 17-23 and 28 will be completed if an inspection is being carried out
Inspection and Test - the testing in items 24v and 26 should always be preceded by inspection.
9/11 ,The make, model and serial number of the item of equipment should be inserted ,
12/14 , The voltage for which the equipment is suitable, the current consumed and the fuse rating should be inserted ,
15/16 , The date of purchase and the guarantee should be completed by the client
17 , The date to be inserted is the date of the inspection or the date of the inspection and testing ,
18 , Environment and use. It should be confirmed that the equipment is suitable for use in the particular environment and is suitable for the use to which it is being put ,
19 , Authority is required from the user to disconnect equipment such as computers and telecom equipment - where unauthorised disconnection could result in loss of data , Authority should also be obtained if such equipment is to be subjected to the insulation resistance and electric strength tests.
20 , Socket-outlet/flex outlet. The socket or flex outlet should be inspected for damage including overheating.
If there are signs of overheating of the plug or socket-outlet, the socket-outlet connections should be checked as well as the plug. This work should only be carried out by an electrician
21/23 , The inspection required is described in Chapter 14 of the Code of Practice for In-Service Inspection and Testing of Electrical Equipment.
24 / 27 ,Tests. The tests are described in Chapter 15 of the Code of Practice for In-
Service Inspection and Testing of Electrical Equipment. The tests should always be preceded by the Inspection items 17-23 and 28. The instrument reading is to be recorded and a tick entered if the test results are satisfactory
28 , Functional Check - a check is made to ensure that the equipment works properly
29 , Comments/other tests. Additional tests may be needed to identify a failure more clearly or other tests may be carried out such as a touch current measurement. An additional sheet may be necessary, which should be referenced in the box on this record
30 , OK to use - ‘YES’ should be inserted if the item of equipment is satisfactory for use, ‘NO’ if it is not ,