***Useful Information for Apprentices***

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“ General Health and Safety at Work “

Question 1.1
What do the letters CDM stand for ?
A: Control of Demolition and Management Regulations
B: Control of Dangerous Materials Regulations
C: Construction (Demolition Management) Regulations
D: Construction (Design and Management Regulations ) Answer: D )
Question 1.2
Identify one method of enforcing regulations that are
available to the Health and Safety Executive:
A: Health Notice
B: Improvement Notice
C: Obstruction Notice
D: Increasing insurance premiums
Answer: B Improvement notices require action to achieve standards which meet health and safety law :
Question 1.3
What happens if a Prohibition Notice is issued by an
Inspector of the local authority or the HSE ?
A: The work in hand can be completed, but no new work started
B: The work can continue if adequate safety precautions are put in place
C: The work that is subject to the notice must cease
D: The work can continue, provided a risk assessment is carried out,
Answer: C The work covered by a prohibition notice must cease until the identified danger is removed.
Question 1.4
Health and Safety Executive Inspector can ?
A: Only visit if they have made an appointment
B: Visit at any time
C: Only visit if accompanied by the principal contractor
D: Only visit to interview the site manager
Answer: B Inspectors have a range of powers, including the right to visit premises at any time.
Question 1.5
A Prohibition Notice means:
A: When you finish the work you must not start again
B: The work must stop immediately
C: Work is to stop for that day only
D: Work may continue until the end of the day
Answer: B The work activity covered by the prohibition notice must cease, until the identified danger is removed ,
Question 1.6
In what circumstances can an HSE Improvement Notice be issued ?
A: If there is a breach of legal requirements
B: By warrant through the police
C: Only between Monday and Friday on site
Answer: A Improvement notices require action to achieve standards which meet health and safety law .
Question 1.7
What is an “Improvement Notice”?
A: A notice issued by the site principal contractor to tidy up the site
B: A notice from the client to the principal contractor to speed up the work
C: A notice issued by a Building Control Officer to deepen foundations
D: A notice issued by an HSE/local authority Inspector to enforce compliance with health
Answer: D Improvement notices require action to achieve standards which meet health and safety law .
Question 1.8
If a Health and Safety Executive Inspector issues a“ Prohibition Notice”, this means that:
A: the Site Manager can choose whether or not to ignore the notice
B: specific work activities, highlighted on the notice, must stop
C: the HSE must supervise the work covered by the notice
D: the HSE must supervise all work from then on
Answer: B Prohibition notices are intended to Stop activities which can cause serious injury.
Question 1.9
Which one of the following items of information will you find on the Approved Health and Safety Law poster?
A: Details of emergency escape routes
B: The location of the local HSE office
C: The location of all fire extinguishers
D: The identity of the first aiders
Answer: B The poster also lists the persons with health and safety responsibilities, but not first aiders.
Question 1.10
Who is responsible for signing a Company Safety Policy ?
A: Site Manager
B: Company Safety Officer
C: Company Secretary
D: Managing Director
Answer: D The Health and Safety at Work Act requires the most senior member of management to sign the health and safety policy
statement.

Question 1.11
Which one of the following must be in a company’s written Health and Safety Policy:
A: Aims and objectives of the company
B: Organisation and arrangements in force for carrying out the health and safety policy
C: Name of the Health and Safety Adviser
D: Company Director’s home address
Answer: B This requirement appears in the Health and Safety at Work Act.
Question 1.12
Employers have to produce a written Health and Safety Policy statement when:
A: A contract commences
B: They employ five people or more
C: The safety representative requests it
D: The HSE notifies them
Answer: B This is a specific requirement of the Health and Safety at Work Act.
Question 1.13
Companies employing five or more people must have a written Health and Safety Policy because:
A: The principal contractor gives them work on site
B: The HSAWA 1974 requires it
C: The Social Security Act requires it
D: The trade unions require it
Answer: B
Question 1.14
What do the letters HSC stand for ?
A: Health and Safety Contract
B: Health and Safety Consultant
C: Health and Safety Conditions
D: Health and Safety Commission Answer: D
Question 1.15
Which ONE of the following statements is correct ? The Health and Safety Executive is:
A: a prosecuting authority
B: an enforcing authority
C: a statutory provisions authority
Answer: B The Health and Safety Executive enforces health and safety legislation.
Question 1.16
The Health and Safety at Work Act requires employers to provide what for their employees?
A: Adequate rest periods
B: Payment for work done
C: A safe place of work
D: Suitable transport to work
Answer: C This is a specific requirement of Section 2 of the Health and Safety at Work Act.
Question 1.17
The Health and Safety at Work Act 1974 and any regulations made under the Act are:
A: Not compulsory, but should be complied with if convenient
B: Advisory to companies and individuals
C: Practical advice for the employer to follow
D: Legally binding Answer: D
Question 1.18
Under the Health and Safety at Work Act 1974, which of the following have a duty to work safely?
A: Employees only
B: The general public
C: Employers only
D: All people at work
Answer: D Employers, employees and the self-employed all have a duty to work safely under the Act.
Question 1.19
What is the MAXIMUM penalty that a Higher Court, can currently impose for a breach of the Health and Safety at Work Act?
A: £20,000 fine and two years imprisonment
B: £15,000 fine and three years imprisonment
C: £1,000 fine and six months imprisonment
D: Unlimited fine and two years imprisonment
Answer: D A Lower Court can impose a fine of up to £20,000 and/or up to six months imprisonment for certain offences. The potential fine in a Higher Court, however, is unlimited and the term of imprisonment can be up to 2 years.
Question 1.20
What do the letters ACoP stand for ?
A: Accepted Code of Provisions
B: Approved Condition of Practice
C: Approved Code of Practice
D: Accepted Code of Practice
Answer: C An ACOP is a code of practice approved by the Health and Safety Commission.

Question 1.21
Where should you look for Official advice on health and safety matters?
A: A set of health and safety guidelines provided by suppliers
B: The health and safety rules as laid down by the employer
C: Guidance issued by the Health and Safety Executive
D: A professionally approved guide book on regulations
Answer: C The HSE is the UK enforcing body and its guidance can be regarded as ‘official’
Question 1.22
Regulations that govern health and safety on construction sites:
A: apply only to inexperienced workers
B: do not apply during ’out of hours’ working
C: apply only to large companies
D: are mandatory ( that is, compulsory )
Answer: D The requirements of health and safety law are mandatory, and failure to follow them can lead to prosecutions.
Question 1.23
Which of the following statements is correct ?
A: The duty for health and safety falls only on the employer
B: All employees must take reasonable care, not only to protect themselves but also their colleagues
C: Employees have no responsibility for Health and Safety on site
D: Only the client is responsible for safety on site
Answer: B The responsibility for management of Health and Safety Act at Work rests with the employer
Question 1.25
Which of the following is correct for risk assessment?
A: It is a good idea but not essential
B: Only required to be done for hazardous work
C: Must always be done
D: Only required on major jobs
Answer: C There is a legal requirement for all work to be suitably risk assessed.
Question 1.26
In the context of a risk assessment, what do you understand by the term risk?
A: An unsafe act or condition
B: Something with the potential to cause injury
C: Any work activity that can be described as dangerous
D: The likelihood that harm from a particular hazard will occur
Answer: D Hazard and risk are not the same. Risk reflects the chance of being harmed by a hazard
Question 1.27
Who would you expect to carry out a risk assessment on your working site?
A: The site planning supervisor
B: A visiting HSE Inspector
C: The construction project designer
D: A competent person
Answer: D A risk assessment must be conducted by a 'competent person’.
Question 1.28
What is a HAZARD ?
A: Where an accident is likely to happen
B: An accident waiting to happen
C: Something with the potential to cause harm
D: The likelihood of something going wrong
Answer: C Examples of hazards include: a drum of acid, breeze blocks on an elevated plank; cables running across a floor.
Question 1.29
What must be done before any work begins ?
A: Emergency plan
B: Assessment of risk
C: Soil assessment
D: Geological survey
Answer: B This is a legal requirement of the Management of Health and Safety at Work Regulations.
Question 1.30
Complete the following sentence: A risk assessment
A: is a piece of paper required by law
B: prevents accidents
C: is a means of analysing what might go wrong
D: isn’t particularly useful
Answer: C Risk assessment involves a careful review of what can cause harm and the practical measures to be taken to reduce the risk of harm.

 

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● Any electrically conductive object will conduct an induced current if it is placed in a changing magnetic filed :
● Eddy currents are circular induced current :
● Eddy currents generate their own magnetic fields :

● A magnetic field is generated anytime an electrical current flows through a conductor .
● The magnetic field around the conductor flows in closed loop’s .
● Wrapping the wire into a coil creates an Electromagnet .
● Wrapping the wire around a piece of Iron creates a Solenoid .

● Field intensity is a term used to describe the strength of the Electromagnetic field .
● Field intensity is determined by the amount of Electrical current flowing in the wire .
Field Direction ● The right-hand-rule can be used to describe the direction of the Electromagnetic field . [ Current ]

The Parallel Circuit :-
Like the Series circuit . Parallel circuits also contain a Voltage ( Current ) source as well as wires and other components .
The main difference between a Series circuit & a Parallel circuit is in the way the components are connected . In Parallel circuit the electricity has several paths that it can travel .

 

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►This is my Understanding .

Identify : for each of the following a typical use of the following Drawings .

1) Assembly Drawings .
2) Block Diagrams .
3) Circuit Diagrams .

1) Shows . the component parts ( in an exploded view ) of the equipment which is to be worked on . Could be used for dismantling & reassembling equipment – plant .
2) A. Block diagram shows the sequence of operation-control set out as Blocks on a plan . it does not show the Actual position of the Item .
3) Shows . the wiring system of the Plant including . Isolation . may Not necessarily show the connections of components .

[ PS. Chaps . Dan is Complaining about all The Thank You.s Coming in all at the Same Time ] The Forum can’t handle it Amber . ] ◄◄ Now am Stop Asking ???

 

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How does an increase in temperature affect the résistance of most materials ?
a) It doesn’t
b) Minimal affect
c) As temperature rises so does a material’s resistance *
d) As temperature rises a material’s resistance will decrease

What is resistivity ?
a) An individual material’s resistance to a current *
b) The amount of electrons flowing past a point per second
c) The electromotive force pushing a current

What is an electromagnet ?
a) A material, when inserted into a
strong magnetic field exhibits a magnetic force of its own
b) A material which is attracted to magnets
c) A material which is not attracted to magnets
d) A field produced when there is an electrical current flowing through a conductor *

Which of the following is a conducting material ?
a) Iron
b) Silicon *
c) Glass
d) Gold

10 What does e.m.f. stand for ?
a) Electro-magnetic force
b) Electrical-motive force
c) Electro-motive force

Why is copper better than aluminium as a conductor ?
a) It’s cheaper
b) It’s more freely available
c) It has better conductivity *
d) It has a greater tensile strength for use in overhead lines

What does RCD stand for ?
a) Residual current device
b) Residual contact device *
c) Reckless current deviation
d) Residual current dexterity

What is a semiconductor ?
a) A material which is a good conductor
b) A material which is a good insulator
c) A material which is neither a good conductor nor a good insulator and sits somewhere between the two *
d) A material which is both a good conductor and a good insulator

Which of the following is not an advantage of high-frequency fluorescent circuits ?
a) Higher lamp efficacy
b) First-time starting
c) Noise free
d) The initial cost is cheaper than glow-type switch starts *

Which of the following is not an example of discharge lighting ?
a) Semi-resonant starting
b) High frequency
c) Stroboscopic effect
d) Tungsten halogen lamps *

Which of the average life of a linear tungsten halogen lamp ?
a) Up to 500 hours
b) Up to 1000 hours
c) Up to 2000 hours *
d) Up to 2500 hours

q1 What common type of steel conduit is best for in damp conditions ?
a) Galvanised
b) Solid-drawn
c) Black enamel
d) Seam-welded

q2 What are set bends in steel conduits used for ?
a) When a conduit run changes direction by less than 90 degrees *
b) To go round a corner or change direction by 90 degrees
c) When a surface levels changes or when terminating into a box entry
d) When passing obstacles

What is a strap saddle used for ?
a) Fixing conduit to an even surface
b) Fixing conduit to a cable tray or steel framework *
c) Fixing conduit to girders and I-beams
d) Used when it is necessary to clean around the conduit

What type of trunking is used in offices . schools , & Colleges ? [ Dado trunking ] **
a) Multi-compartment trunking
b) Skirting trunking *
c) Busbar trunking
d) Flush cable trunking

What clips or ties will not maintain circuit integrity during a fire ?
a) Copper
b) steel
c) Nylon *
d) Copper-coated

What type of conduit would you use within metal stud partitioning ?
a) PVC conduit
b) Flexible conduit **
c) Steel conduit *
d) Plastic conduit

What does MCB stand for ?
a) Moulded Circuit Breaker
b) Major Current Boomer
c) Miniature Circuit Breaker *
d) Major Calibration Mechanism

(4)

 

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Got the Wife’s glasses on . must go to Specsaver.s …. a) Residual current device *
what would you use on Agricultural / Farm . " Hint " Cows Urinate Corrodes What ? : [ steel conduit , Galvanised No ] take you best Guess try the 17th Edition . What can you wash down easy !!!!!!!!!!!!

 

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1 Why is plastic conduit more appropriate for farm installations ?
a) It’s cheaper * [ Heavier Conduit ] 17th Edition ……….
b) It retains heat
c) It expands better than alternatives
d) It’s more suitable for damp conditions

6 Which type of diagram would be most useful when running a cable between two buildings on a site
a) Site plan *
b) Block diagram
c) Location diagram
d) Circuit diagram

 

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Power Factor Correction

What is Power Factor ?

Power Factor is a characteristic of alternating current, and can be defined as the ratio of working power to total power.

Alternating current has the following components

* Real Power – [ Power which produces work ( kW )
* Available Power – [ Power delivered or total volt amp ( kVA )
* Reactive Power – [ Power needed to generate magnetic fields required for the Operation of Inductive electrical equipment ( kVAR ) No useful work is performed with Reactive Power .

Therefore the unitless Power Factor is obtained from
Power Factor = Real Power = kW / Available Power kVA

Power Factor is generally represented as a percentage or a decimal. Perfect power factor, often referred to as unity power factor would be 100% or 1.0.

[ power factor is only ( 1 ) or less . & rarely ( 1 ) ]

What is Power Factor Correction?

All flowing current causes losses in the supply and distribution system. A load with a power factor of 1.0 results is the most efficient loading for the supply and a load with a power factor of 0.6 will have much higher losses in the supply system. These loses have to be paid for, and result in higher utility bills. It is possible to modify the supply and distribution system to bring the power factor closer to unity. This is called power factor correction.

Correcting Power Factors

The simplest form of power factor correction, sometimes referred to as static correction, is by the addition of capacitors in parallel with the connected inductive load. The resulting capacitive current is a leading current and is used to cancel the lagging inductive current flowing from the supply. The capacitors can be applied at the starter, or the switchboard or at the distribution panel. Note that power factor correction should not be used when a motor is controlled by a variable speed drive.
Rather than correcting each individual load, the total current supplied to the distribution board can be monitored by a controller which switches capacitor banks to maintain the power factor at its predetermined setting. The controller switching in capacitors as new loads come on line, and switching out capacitors as loads go off line. This type of correction is sometimes referred to as bulk correction.

Common Inductive Loads

Commonly used electrical equipment that provide an inductive load include lighting circuits, heaters, arc welders, distribution transformers and electric motors. …… Etc

** power factor correction offers improved voltage regulation due to reduced lower voltage drop. Also, by considering power factor correction at the design stage it is possible to reduce capital investment through reduction in the size of transformers, switchgear and cable diameters.

( K)

 

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● What are the Examples of Inductive Load !!!!!!!!!!

Some well known examples are a motor, relay, solenoid valve, electromagnet, transformer, lamp ballast, and an ignition coil. However, in electronics, even a piece of wire can be considered an inductive load because it has the property of inductance. An inductor is a device that produces a magnetic field while an electrical current is passed though it.

● What are the Examples of Inductive Load !!!!!!!!!!

Any devices that have coils of wire in there manufacture can be classed as inductive loads. e.g. motors, solenoids and contactor coils are a few. Example of resistive loads can be baseboard heaters, filament light bulbs, toasters and stove top elements.

● What is the difference between a Resistive Load & an Inductive Load !!!!!!!!!!!!!

Resistive Load An electrical load which is characteristic of not having any significant inrush current. When a resistive load is energised, the current rises instantly to it's steady-state value, without first rising to a higher value. An electrical load in which voltage and current are converted to energy in the form of heat; i.e., an electrical heater, incandescent bulb.
Inductive Load An electrical load which pulls a large amount of current (an inrush current) when first energized. After a few cycles or seconds the current "settles down" to the full-load running current.
The time required for the current to "settle down" depends on the frequency or/and the inductance value of the Inductive load

( K )

 

[Phil]

Singles Old Wiring :- ( 2 – Way Wiring Problem ) “ Megger at the Ready “

A lot of Testing !! or Trial & Error
Attention to which Wire was which when you Removed the Old Switches . ( it depends on how the Electrician Set it Up )

The Three Reds without more info can’t say which Wire goes where but again the ( Common ) is the Important One so trying all ( Three Combinations ) should not take Long . ( Mark Wires 1 . 2 . 3. and Try each one in ( Common ) with Other Two in ( L1 . L2 ) Until it Works .

It is also suffice to mention that if however you mixed up the Wires . or Terminated them upside down . it will not Cause any major problems. The worst you faced might be a Light that cannot be switched Off or a Switch that works in the Opposite direction . in any case . a Small Relocation of the Wires for the Affected Switch should take care of the Problem

The Wiring is as Following :
( Red ) to ( L1 ) ↔ ( Red ) to ( L2 ) & Black to ( Common ) if Twin Used .
Black Wire should be your ( Common ) as a Rule . But not all the Time ??

It should be The ↔ ( Three Red Wire or One Black ) or Three – Single ( Red Wire ) ↔ ( Two Red Wires & One Black Wire ) Two – Way
( One ( Red Wire ) which is in the ( Com : Mains ) ↔ ( L1 Red Wire 2 ) ↔ ( L2 Red Wire 3 ) ↔ Two – Way ▼
( One ( 1 Red Wire / Switch Live / Return ) to Light Fitting ) ↔ ( L1 Red Wire 2 ) ↔ ( L2 Red Wire 3 ) Plus Earth ????

It should be ( Red Wire ” Mains “ ) from the Three-Single Cable’s which is in the ( Common Position ) on your First Light Switch .
You should have ( Red or Black / Two – Red ( from the Light Switch ) Connected across ( L1 ) & ( L2 ) Now you have the Three- Single Wires Connected across ( L1 ) & ( L2 ) & ( Common ) Permanent Live Switch Live

( Two – Way switches work together to Operate a Light from Two different Locations ) 3 – wires in One Light Switch . Plus Earth ????

You may come across . One ( Red ) to the ( Common ) & Bridge to other ( Common(s) ) Two Switches . 3-Gang 2-Way.
( To find out which are Strappers or Singles . Join One end of a Twin & Earth together & Bell Out ) Continuity

Feed from Consumer Unit
( Only a Switched Live . if we turn off the Light at the Switch there is No power to the Ceiling Rose ) ( Not Use Loop in Loop Out Drawbacks )

( Make sure that they are Earth in a 2-Gang Switch Old Wiring or Any Lighting )
You may see this in Old Wiring :- Twin & Earth . Earth Used as ( Common ) Permanent Live ( Rare !! )
Twin & Earth because the CPC is Bare throughout its Length & doesn’t get away from the Fact there is not a CPC at the Switch . ( Previous Electrician )

514.4.2 : Protective Conductor . The bi-colour combination Green -&-Yellow shall be used exclusively for identification of a Protective Conductor and this combination shall not be used for any other purpose .

Single-Core cables that are Coloured Green-&Yellow throughout their length shall only be Used as a Protective Conductor and shall not be Over-Marked at their Terminations . Except as permitted by Regulation 514.4.4.

( 2392-10 : The Only way is the Right Way . Any Compromise is Wrong . in these Circumstance’s Use the Regulation’s as your Excuse / Lever / Justification for Insisting that it Need’s to be Ripped Out & Started again .

Radial Circuit is used for Lighting Circuits

Loop-in-Wiring :-
With loop-in-wiring . the Cable from Ceiling rose to switch has 3 Conductors . Namely Earth . Unswitched Return Live & Switched Live .

Sockets :- RCDs ?? May be Prone to Nuisance Trips
RCDs is not a Regulation requirement for most Socket(s) . Only Socket(s) likely to be Used by Outdoor Equipment are required to be Powered via an RCD . ( Let me Ask you . Would you Use a dedicated Socket feeding a Fridge Freezer on a RCD ( Cause Defrosting ) non-RCD side

Sockets may be Wired on Ring Circuits or Radial Circuits ( Radial !! More Copper . Connection Faults have greater Consequences ) . Mostly Rings are Used . as they use Less Copper for most Circuit Layouts . They have Safety Advantages over Radial Circuits can provide more power . and cover More Floor Area per Circuit .
20A Radials use 2.5mm2 or 4mm2 Cable : p/363 . Regs
32A Radials use 4mm2 Cable :

It is Common to have a Ring Dedicated just for Sockets in the Kitchen Since that is where you will find many of the Highest power Consuming Appliance
( Design ) – Kitchens are supplied by One Ring Circuit . [ Larger Kitchens – Load & Diversity – Calcs ]

Electric Shower . Own high Current Cable . Cooker Own high Current Cable . [ p/362 – Regs . (iii) Connecting Cookers . Ovens & Hobs with a rated power Exceeding 2 kW on their Own dedicated Radial Circuit ]

Why the Breaker had Tripped ?? Resetting a Breaker !! Unable to hold the “ On “ Position (i) Mechanical Problem Rare ) (ii) it is Retripping for a Short Circuit it’s doing it’s Job )

[ Solution !! Another good way is to Take the Panel’s Cover Off . Remove the Wire from that Breaker . & see if it Resets & Stay On ]
?? But if the Original does stay “ On “ when Deprived of it’s Wire . Then it has Indeed been Responding to a [ Short Circuit ] Yeah

Blinking or Flickering Lights
[ Solution !! you may be dealing with a Poor Connection somewhere in your System . it is Commonly at an Outlet . Light . Switch / or Loose Connection ]

The Short Circuit . ( ● Most Breakers can stand up to Repeated Shorting )
Since the Short . the Earth Fault . the Arc-Fault ( Unintended Continuity )
A Live to Earth Short [ Breaker Earth Fault ) is more Common than a Line to Neutral Short .

First :- On the dead Circuit . Unplug everything & turn all On/Off switches Off . & turn Only One Switch the Other Way . “ Try Reset “ then On if the Breaker stays On . one of the Items you Disconnected from the Circuit has the Short in it . so reconnect One at a Time . Turning power back On each time That should Identify the Culprit .

The Causes of Problems ??
The biggest Cause for Electrical Problems in Old Homes is simply the Age of the Home / Wiring

Thanks to G

 

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Rafter’s : ( Do Not Drill into them )
Are used to form the Roof Structures of the Building & are Supported by the Top Plate .

Ceiling Joist’s : ( Check : Cables through Joist’s O.S.G. p/59 ) & Part P .
Are horizontal framing member’s that sit on top of the wall framing . They form the Structural framework for the Ceiling . ( if there is a Floor above . these Ceiling Joist’s become . Floor Joist’s ) & also form the Structural Framework for the Floor above .

Understanding Electricity :
A Household Electrical System can be Compared with a Homes plumbing system .
Electrical Current flow’s in Wires in much the same way that water flows inside pipes . both Electricity & Water enter the home . are Distributed throughout the house . do their “ Work “ & Exit .

In plumbing “ Water “ first flows through the pressurised Water supply System . in Electricity Current first flows along Live Wire’s . Current flowing along Live Wire’s also is Pressurised . the Pressure of Electrical Current is called Voltage .

Large Supply pipes can carry a Greater Volume of Water than small pipes . Likewise . Larger Electrical Wire’s carry more Current than Small Wire’s . this Current – Carrying – Capacity of Wire’s is called “ Amperage “

Water finally leaves the home through a Drain System . which is NOT Pressurised . Similarly . Electrical Current flows back through Neutral Wire .
The Current in Neutral Wire’s is NOT Pressurised ( At Zero Voltage ) ↔ ( Current Return’s UNDER no Pressure Normally ↔ This is not under Fault Condition’s )

 

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17th Edition Conduit : Definitions p/22 . A part of a closed wiring system for cables in Electrical Installations. allowing them to be drawn in & /or replaced , but not inserted laterally .
( Plain English )
Conduit : ( A Metal or Plastic Tube used to Protect Wire’s ◄ ) - Metal Conduit / Continuity / Wander Lead may be Used .
Continuity : an Uninterrupted Electrical Pathway through a Circuit or Electrical Fixture .

 

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Silver : is the most Conductive Material . it’s Price . etc .
Copper ; is the Second most Conductive Element . ( Copper as the Best Alternative )

( Plain English Simplified ) Theory Behind : ( V + / - ) → ( I ) ( R )

( V ) = Voltage ( Pressure behind Current Flow )
( I ) = Amp’s ( Flow of Current )
( R ) = Ohm’s ( Résistance or how much Current will flow Through a Component )

High Voltage moves a Large Current .
Low Voltage moves a Small Current .

 

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A Fundamental Question .
Will the Protection Device Function ?? During a Fault Condition ?

- Let’s consider the Difference between Fault Level Current Rating & ( PSCC ) Prospective Short Circuit Current . the Fault Level Current Rating can be seen on a ( MCB ) Circuit Breaker . Example as 6kA . ↔ This means that the ( MCB ) is able to “ Withstand up to 6000 Amp’s for a Short Period without being Destroyed . ( Tripping Time depends on the MCB )

( PSCC ) Prospective Short Circuit Current . measured in an Installation is used to Consider whether the Circuit is Capable of Carrying sufficient Current so as to Trip the Overload Device in the Specified Time .

High values of ( PSCC ) Prospective Short Circuit Current . can vary Dramatically due to small changes in Impedance . ??
V = Z x I
Example : I = 230 / 0.03Ω = 7666. Amps
Or : I = 230V ÷ 0.01Ω = 23000 Amps

Notice : The vast change in Current for a very Minor Difference in Impedance , ( Low Impedance is very Difficult & High Current is Required )

 

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Re: PIR reporting and competent persons.

“Apprentices “ Useful Junk “ BS-951 ( We Use this Day in & Day Out without thinking about it ) Yeah . All in a Word

Specifies the performance and important Mechanical requirements for metal clamps that are used to provide Mechanically and Electrical Sound earthing and bonding connections to metal tubes. The information . relates to the correct selection and installation of such clamps within electrical installations.

► Misuse of BS-951

Cases of misuse of BS 951 clamps are occasionally found, some examples of which are given below. ( You will see this in your Travels ! )

Fitting a BS-951 Clamp to the Armour or Metallic Sheath of a Cable ( the Why’s !! )

BS 951 states that clamps to this standard are Not intended for connection to the armour or sheath of a cable and requires the packaging of the clamp to include the warning “ Not intended for Use on the Sheath or Armour of a Cable “. This is because the Action of tightening the clamp is liable to damage the cable, for example by crushing the bedding or insulation or by causing the metal in a lead sheath to Cold – Flow . Such damage may result in High Résistance and unreliability in the electrical connection between the clamp and the armouring or metallic sheath, and may even result in an electrical fault within the cable, Fitting a BS 951 clamp to the armour or metallic sheath of a cable is therefore Unacceptable .

Fitting a BS-951 Clamp which is Unsuitable for the Pipe Diameter & / or Cable Size :

A BS 951 clamp must be correctly selected for both the size of pipe or tube to which it is to be fitted and the size of cable. Fitting a clamp which is unsuitable in either of these respects is liable to be a departure from the requirements of Regulations 526.1 and/or 526.2 of BS 7671 relating to durable electrical continuity, adequate mechanical strength, and appropriate selection of a means of connection.

● To avoid corrosion due to electrolytic action, Aluminium Labelsof BS 951

Installing a Clamp in an Inaccessible Position :

Like all types of electrical connection that are not excused by Regulation 526.3 of BS 7671, the electrical connections between a BS 951 clamp, the pipe (or other tube) to which it is attached, and the protective conductor connected to its terminal must be accessible for Inspection , Testing and Maintenance (Regulation 543.3.3 refers).

BS-7671 Requirements ! ( The Only Trouble with the Regulations . they are all Scatted to the 4 Winds )

● Warning notice-earthing and bonding connections ( 514.13 )
● External influences (Section 522 )
● Connections between conductors and a conductor and equipment (526.1)
● Accessibility of connections (526.3 )

Résistance to Corrosion :

Clamps to BS 951 are made in a choice of different metals, to suit differing levels of corrosion that are likely to be encountered in service. In order to comply with the requirements of Section 522 (Selection and erection of wiring systems in relation to external influences) of BS 7671, it is important to select a clamp which is suitable for the expected conditions in the particular location where it is to be installed. For example, some clamps are intended for use only in dry conditions, whilst others are suitable for damp locations such as bathrooms. Some manufactures of clamps use different colours to indicate the type of application and environmental conditions for which the clamp is intended, similar to the colours shown in the illustration below. Where doubt exists as to the suitability of a clamp for use in a particular environment, advice should be sought from the manufacturer.

Terminations :

The termination on a BS 951 clamp for the protective conductor is separate from the means of tightening and locking the clamp for making electrical contact with the tube.

A screw termination is capable of accepting one of the following: Etc .

● a conductor clamped under a screw head provided with a captive washer so that the screw head does not act directly on the conductor; Etc.

● “ Phil can this be move this to the Right Place “ Please . Thank you . Amber . Ta.