Re-take - Useful Information for 2394 :

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( A3 ) They are minor changes

( Minor electrical installation works certificate )
( Periodic inspection report )

 

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Appendix 6 – Model forms for certification and reporting

The schedule of inspections (for new work only) has been replaced by examples of items requiring inspection during initial verifications (which must be appended to the Electrical Installation Certificate).

A small number of changes to the Electrical Installation Condition Report and associated notes have been made, including a requirement to carry out an inspection within an accessible roof space where electrical equipment is present in that roof space.

 

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Under (A3) enclosures will need to be made from a suitable non-combustible material, or be enclosed in a cabinet / enclosure made from a suitable non-combustible material complying with regulation 132.12.

My Question for the IET & Niceic , Primary cause of fires is (( loose connections )) why not address this instead of containing the fire.

 

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.....My Question for the IET & Niceic , Primary cause of fires is (( loose connections )) why not address this instead of containing the fire.

This would be my question too, rather address the root cause than the symptoms.

 

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Sent for the (BS 7671:2008+A3:2015)

Earthing & Bonding have often been confused as being the same thing , when in fact the two are quite distinct from each Other .
The term “ Earth bonding “ this essentially is a meaningless term that has somehow found its way into everyday vocabulary for some Electricians’

Let. Use the word Bonding ) is the connection of All metallic-parts using main-protective-bonding-conductor .

The principal of “ Earthing “ is to prevent , by limiting the duration of touch voltages .

Tests : ( before the supply is connected )
Continuity of protective conductors including main and supplementary equipotential bonding. (Regulation 612.2.1)
Test method 1 :- Protective-conductor(s) Testing the continuity of circuit-protective-conductor’s
Test method 2 :- Bonding-conductor’s. Testing the continuity of Earthing & Bonding-conductor’s & circuit-protective-conductors.

Continuity of protective-conductor(s) .. ( CPC ) Regulation’s have state the fact’s , Its continuity shall be assured .
The purpose of this test is to verify that the (( Circuit-protective-conductor(s)) form’s a continuous path around the circuit under test .

( before the supply is connected )
The test is carried out ( using either or both methods )
( Accessory ) Test method 1 :- Test between the line-conductor & the circuit-protective-conductor ( Link used ) to Accessory(s) .. ( Loop )
( Accessory ) Test method 2 :- Test between Earth-bar to circuit-protective-conductor ( Wander-lead - R[SUP]2[/SUP] )

O.S.G.
Test method 1 : ( for circuit protective conductors )
in addition to checking the continuity of the protective conductor, also measures ( R[SUP]1[/SUP] + R[SUP]2[/SUP] ) which, when added to the external impedance (Ze) enables the earth fault loop impedance (Zs) to be checked against the design value .

Note : ( R[SUP]1[/SUP] + R[SUP]2[/SUP] ) is the sum of the resistances of the line conductor ( R[SUP]1[/SUP] ) and the circuit-protective-conductor ( R[SUP]2[/SUP] ) between the point of utilisation and the origin of the installation .

Use : an ohmmeter capable of measuring a low résistance for these tests.
Regulation 612.2.1. .. A continuity test shall be made . Etc. refer

Test method 1: can only be used to measure ( R[SUP]1[/SUP] + R[SUP]2[/SUP] ) for an “ all-insulated “ installation.
Re-cap : Note O.S.G. tell us .
Installations incorporating steel-conduit , steel-trunking . micc ( mineral insulated copper cables , & PVC / SWA cables will produce (( parallel paths )) to protective-conductors . Such installations should be inspected for soundness of construction and test method 1 & 2 used to prove continuity

Protective-earthing ( PE )
Earthing of a point or points in a system or in an installation or in equipment for the purposes of safety

Protective-conductor ( PE )
A conductor used for some measures of protection against electric shock and intended for connecting together any of the following part.s:
i) Exposed-conductive-parts .. (( such as the conducting cases of equipment ))
ii) Extraneous-conductive-parts.
iii) The main earthing-terminal.
iv) Earth electrode(s).
v) The earthed point of the source, or an artificial neutral .

Circuit-protective-conductor , can take many forms : refer
Types of protective-conductors 543.2.
i) A single core cable .
ii) A conductor in a cable .
v) A metal covering, for example , the sheath , screen or armouring of a cable .
v) refinded, Conducting cable enclosures such as Conduit or Trunking . ( Metal )
vi) An extraneous-conductive-part complying with Regulation 543.2.6.

( Type ) of circuit-protective-conductor(s)
- Earth-conductor .
- Earth-terminal .
Separate circuit-protective-conductor .. fixed appliances .
Circuit-protective-conductor .. in flexible cord .
Circuit-protective-conductor .. in sheathed wiring . Ring / Radial circuit .
Ceiling rose , earth-terminal even if all insulated .. switch
Conduit .

Note : Water / Gas pipes , possible future change to ( Plastic ) .. non-conducting-pipes.
Supplementary equipotential bonding : .. Supplementary bonding is additional protection to fault protection.

 

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O.S.G. : Polarity
( Dead ) ... Before the supply is connected ... ( By continuity methods’ )
( Live ) ... With the supply connected and energized ... re-check of polarity, using an approved voltage indicator .

Polarity (Regulation 612.6) .. ( By continuity methods )
it is important to confirm that :
i) overcurrent devices and single-pole controls are connected in the line conductor only .
iii ) Socket-outlet(s) & similar accessory polarities are correct .

O.S.G. After connection of the supply , polarity must be checked using an approved ( Voltage indicator or a test-lamp ) in either case with fused leads - GS-38 .

Polarity checks must be carried out on all circuit’s , i.e. Power & Lighting .

Testing checklist O.S.G .
Polarity : this includes checks that single-pole control and protective devices .. switches , circuit-breakers , fuses , are connected in the line conductor only .
Polarity : Neutral conductor and that wiring has been correctly connected to socket-outlets and other accessories .

GN-3 : 612.6. Polarity testing
The polarity of all circuits must be verified before connection to the supply, with either an ohmmeter or the continuity range of an insulation & continuity tester

( Simplicity ) Alternative , polarity can be verified by visually checking core colours at terminations, thus verifying the installer’s connections .
Whatever method is used, polarity checks are required at all points on a circuit.

 

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Just back for my Torque screwdriver . off to the wholesaler now , Pen to Paper , Why ??

Once again, the “ powers that be " The argument on both sides

Some Questions am asking myself ?? (( Manufacturers or Electrician’s ))

Fires have been caused by loose connection(s) We will never hear to end of this .
The most common cause the Neutral not being tightened correctly. On rant mode here .

Just back from a job , to replace down lights to LED . the costumer asked the question, the RCDs keeps tripping why ?? had a look inside the CCU , did hear an arking inside the CCU connection, “ reason “ due to a loose connection, Tail / Neutral
it was the smell of something burning . that got my Attention .

( Start with N ) An Installer replaced a CCU 4 weeks ago, to my dismay the ( Tail ) Neutral was not tightened up making me (( loose connection )
signs of Heavy blacking on the main-switch 100A ( N ) made safe at the moment , going to the wholesaler to get a replacement MK main-switch 100A.
The question the customer asked , Who do I take it up with the ( N****C / Installer ) Yeah , dam right .

This poor person is a pensioner

My gripe .
The way manufacturers make the (( terminals )) It’s a starting point !!

So, in particular, under Amendment 3 enclosures will need to be made from a suitable non-combustible material, or be enclosed in a cabinet / enclosure made from a suitable non-combustible material complying with regulation 132.12.

it's high time the bigwigs listened to the contractor(s). Electricians’

Where does it stop, Socket-outlets , ceiling roses , junction boxes , IP plastic enclosures !!

DNO service cut out so will this need to be incased in a suitable enclosure ( is it fireproof plastic / combustible material)

Something should be done regarding meter tails or the way manufacturers make the (( terminals ))
How many times have you tightened the tails half way through a consumer unit , only to find they are lose again at the end of the job , so who is at fault here .. The way manufacturers make the (( terminals )) Question(s) have to be asked here !!

 

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( A3) Chapter 42 Protection Against Thermal Effects
Regulation 421.1.200 has been introduced and will require switchgear assemblies, including consumer units, to have their enclosure manufactured from non-combustible, or not readily combustible, material, or to be enclosed in a cabinet or enclosure that is constructed of non-combustible, or not readily combustible, material.

This new Regulation is being introduced to help to protect against fire that can result from the overheating of connections within consumer units. Overheating can arise from loose connections and connections that have not been made correctly, for example, the connection of a cable over the insulation.

Regulation 421.1.200. This regulation requires that within domestic (household) premises, consumer units and similar switchgear assemblies shall comply with BS EN 61439-3 and shall have their enclosure manufactured from non-combustible material, or enclosed in a cabinet or enclosure constructed of non-combustible material and complying with Regulation 132.12. This has been developed to safeguard against the risk of fire that can be produced from the overheating of connections in consumer units.

 

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Chapter 41 Protection Against Electric Shock References to ‘ordinary persons’ in Regulation 411.3.3 have now been removed.

This Regulation will require, in accordance with Regulation 415.1, RCD protection for socket outlets up to 20 A (and for mobile equipment up to 32 A for use outdoors) for all installations.
There is, however, an exception for RCD protection (for socket outlets up to 20A) for a specific labelled socket outlet or where a documented risk assessment determines that RCD protection is not necessary.

This means that socket outlets up to 20A in all types of installations, including commercial, domestic and industrial, will need to be protected by a 30mA RCD unless a risk assessment can determine that it’s not necessary

 

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Part 2 Definitions: For example, the definition for ‘skilled and instructed persons’ will be changed. It was also decided that the definition for a ‘competent person’ should be removed, to avoid confusion, as it was considered that some overlap existed between the definition of ‘skilled person’ and ‘competent person’

These changes will be reflected throughout the wiring regulations. For example, Regulation 134.1.1 has been changed from:

"Good workmanship by competent persons or persons under their supervision and proper materials shall be used in the erection of the electrical installation. Electrical equipment shall be installed in accordance with the instructions provided by the manufacturer of the equipment." to: "Good workmanship by skilled (electrically) or instructed (electrically) persons and proper materials shall be used in the erection of the electrical installation. The installation of electrical equipment shall take account of manufacturers’ instructions." Some new symbols have been included in the definitions.

 

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When connecting single-phase loads to a three-phase supply, you must take care to distribute the single-phase loads equally across the three-phases so that each phase carries approximately the same current .

Q) This is called:
a) generation of the phase loads
b) transmission of the load
c) distribution of the load
d) balancing of the load

Balancing single-phase loads
A three-phase load such as a motor has equally balanced phases since the résistance of each phase winding will be the same , Therefore , the current taken by each phase will be equal. when conning single-phase loads to a three-phase supply , to distribute the single-phase loads equally across the three-phases so that each phase carries approximately the same current . equally distributing the single-phase loads across the three-phase supply is known as “ Balancing the load “

The metal structural steelwork of a building is called:
a) the general mass of earth
b) the circuit protective conductor ( CPC )
c) exposed conductive parts
d) extraneous conductive parts

What is Main Protective Bonding ? .. The question is the purpose of Equipotential Bonding
Main protective equipotential bonding connects the main earthing terminal with the following extraneous-conductive-parts
Exposed metallic structural parts of the building .. connecting all accessible metalwork

Equipotential bonding :
Electrical connection which maintaining various exposed-conductive-parts & extraneous-conductive-parts at substantially the same potential .
Extraneous-conductive-parts – this is the structural steelwork of a building

Q&As
To verify or prove a successful electrical isolation you would use a:
a) voltage indicator
b) voltage proving unit
c) set of GS-38 test leads
d) small padlock

To secure an electrical isolation you would use a:
a) voltage indicator
b) voltage proving unit
c) set of GS-38 test leads
d) small padlock

Where a test instrument or voltage indicator is used to prove a supply dead, the same device must be tested to show that it still works using a:
a) voltage indicator
b) voltage proving unit
c) set of GS-38 test leads
d) small padlock

To give adequate protection to the person carrying out a safe isolation procedure, the test instrument must incorporate a:
a) voltage indicator
b) voltage proving unit
c) set of GS-38 test leads
d) small padlock

Hazard may be defined as: ( A3 - 2015 ) reminds us Risk Assessment comes into the Equation now .
- Anything that can cause harm
- the change , large or small , of harm actually being done .

Magnetic circuit through core . Vp ) the primary voltage .. 230V
Magnetic circuit through core . Vs ) the secondary voltage .. 12V
Np ) the number of primary turns .. 800
Ns ) the number of secondary turns

moving the terms around you have a general expression for a transformer: Vp - Vs = Np - Ns
230V to 12V emergency transformer is constructed with 800 turns , Calculate the number of ( Ns ) secondary turns required
Ns = Np Vs / Vp , therefore Ns = 800 x 12V ÷ 230 = 42 turns rounded up . 41.739 13043

 

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( A3 - 2015 ) Skilled Person :
Inspection & Test , Part 6 chapter 61 , change to “ Skilled person ( electrically ) “ being competent in inspection , testing , and certification

Skill wise you will need to be an effective communicator with strong interpersonal skills with an analytical brain as you will need knowledge and experience and continuous improvement. skilled person

(( competent person )) now replaced with skilled electrically

 

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Physics
" You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory !"

Electrical résistance
Electric current is the flow of electrons through a conductor , When the electrons move from one part of the conductor to the other , they collide with other electrons and with the positive ions present in the conductor , Due to these collisions , there is some obstruction or opposition to the flow of electronic current through the conductor . These collisions tend to slow down the speed of the electrons .. ( + / - )

The property of a conductor by virtue of which it opposes the flow of electric current through it is called its résistance.

Factors affecting the résistance of a conductor
The electrical résistance of a conductor ( cable / wire ) depends on the following factors
• length of the conductor
• Area of cross-section of the conductor ( thickness of the conductor )
• Temperature of the conductor
• Material of the conductor ..
Copper have very low résistance

Effect of the length on the résistance of a conductor
On increasing the length of ( cable / wire ) its résistance increases and on decreasing the length of the ( cable / wire ) its résistance decreases
In other words ; the résistance of a conductor is :

Shorter ( cable ) wire .. lower résistance
Longer ( cable ) wire .. higher résistance

Directly proportional to it length ( R / I )
R = résistance
I = length
• if the length of the conductor ( Cable ) is doubled , its résistance also gets doubled
• if the length of the conductor ( Cable ) is halved , its résistance also gets halved .

Effect of the area of cross-section on the résistance of a conductor
The résistance of a conductor is inversely proportional to is area of cross-section

if the area of cross-section of the conductor is doubled , its résistance gets halved .
if the area of cross-section of the conductor is halved , its résistance gets doubled .

 

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The potential difference is measured by an instrument your ( megger ) is always connected in parallel to the two-points across which the potential difference is to be ( measured ) . Little ( rS )

Cable ( wire ) Measuring the potential difference between two-points ( A to B ) by using your megger .. little ( r[SUP]1[/SUP] ) to ( r[SUP]1[/SUP] ) Loop , Continuity

(( Continuity )) of ring-final-circuit (( conductor(s)

Note : Little ( rS )
Step 1 ) Check between each (( end )) in turn
Line-to-line ( r[SUP]1[/SUP] )
Neutral-to- Neutral ( r[SUP] N[/SUP] )
Circuit-protective-conductor to circuit-protective-conductor ( r[SUP]2[/SUP] )

 

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Unit of résistance
SI unit of résistance is Ohms , which is denoted by the symbol Ω .

According to Ohms law
Résistance ( R ) = Potential difference ( V ) ----- Current ( I )
Now , if the potential difference ( V ) is 1 volt &
The current ( I ) is 1 ampere
Then the résistance ( R ) in the above equation will be 1Ω

1 ohm = 1 volt ----- 1 ampere or 1Ω = 1V --- 1A

1 ohm is the résistance of a conductor such that when a potential difference of ( 1V ) is applied to its ends , a current of ( 1A) flows through it