Re-take - Useful Information for 2394 :

[amberleaf]

BS-1361 fuse, Type I and Type II.

BS-1361 Type I rated 240v 16.5kA
BS-1361 Type IIa rated 415v 60/80A 33kA
BS-1361 Type IIb rated 415v 80/100A 33kA

BS-1361:1977:
Specification for cartridge fuses for a.c. circuits in domestic and similar premises

Requirements, ratings and tests for fuse links, fuse bases and carriers. Dimensions and time/current zones for fuse links.
Type I-rated 240V and 5A to 45A for replacement by domestic consumers .
Type II-rated 415V and 60A, 80A or 100A for use by the supply authority in the incoming unit of domestic and similar premises.

The Type I's are little ones that fit in the consumer unit fuseholders.
The Type II's are big ones that fit in the service cut-out fuseholder. ( DNO ) 33kA distributors service heads.

Fuse(s)
On what principle does the fuse operate .

The action of a fuse is based upon the heating effect of the electrical current . During overloads or Short-circuits the fuse gets heated up to melting point due to excessive current and breaks the circuit .

Fuses :
Typical Industrial Applications

( aM ) Motor circuit protection against short-circuit only . ( Partial range )
( gG ) General purpose fuse essentially for conductor protection
( gM ) Motor protection

Fuse : short for fusible link .

BS-1361 Type II fuses are used in electrical mains incomers

 

[amberleaf]

The term ‘ rated current ’ generally means the same as ‘current setting ’, as used in BS-7671 in relation to protection against overcurrent.

Overcurrent instantaneous tripping (‘Type’ of RCBO)

RCBOs conforming to BS-EN-61009-1 are classified into three distinct ‘Types’, known as Type B, Type C and Type D.
according to their instantaneous tripping overcurrent. Instantaneous tripping overcurrent is the minimum value of current causing an RCBO to operate automatically without intentional time delay (that is, within a time not exceeding 0.1 s or 100ms).

BS-EN-61009-1 permits instantaneous tripping to occur at a value of overcurrent, expressed as a multiple of the rated (or nominal) current (In)
Standard values of rated residual operating current given in BS-EN-61009-1 . 0.01A, 0.03A, 0.1A, 0.3A and 500mA / 0.5A.
( by calculation - 30mA ÷ 1000 = 0.03A ) 10 , 30 , 100 . 300mA

Rated residual operating current, IΔn
Rated residual operating current ( IΔn ) of an RCBO is the value of residual current, assigned to the RCBO by the manufacturer, at which an RCBO operates under specified conditions.

Where the function of an RCBO as a residual current device (rather than that as an overcurrent device) is used for fault-protection as part of the protective measure Automatic Disconnection of Supply (ADS)

Residual current breakers conforming to BS-EN-61009 all have a conventional tripping current of 1.45 (In) The related conventional time is 1 hour for circuit-breakers of rated currents (In) up to and including 63 A, and 2 hours for circuit-breakers of rated currents greater than 63 A.

Ambient air temperature, normally of 30°C.

in this case RCBOs :- its contacts are in the Open-position , Regulation’s 537.2.2.2. and 537.3.2.2.

537.2.2.2.
the position of the contacts or other means of isolation shall be either externally visible or clearly and reliably indicated . An indication of the isolated position shall occur only when the specified isolation has been obtained in each-pole .

537.3.2.2.
A device for switching Off for mechanical maintenance or a control switch for such a device shall require manual operation .

the Open-position of the contacts of the device shall be visible or be clearly and reliably indicated .

Note : The indication required by this regulation may be achieved by the use of the symbols “ 0 “ and “ I “ to indicate the open and closed positions respectively .

RCBOs , Suitability for use for isolation and switching Table 53.4. BS-EN-61009-1.
Isolation : Yes (3) Device is suitable for On-load isolation . i.e. disconnection whilst carrying load-current .
Functional switching : Yes .. ( you.re in control )

 

[amberleaf]

Taken from old notes .

2008: 433.1.5.
2011: 433.1.103.

( Ib ) in each leg of cable is not to exceed 20Amps . current will not be the same all round ring-final-circuit .
assumed to be 20A at far end additional ( 12A ) evenly distributed [ 32A + 20 = 52A ÷ 2 = 26A ] L.v.d. = 4 ( 5% ) 11.5 x 1000 ÷ 26A ÷ 18mV = 98.3m
( 4 x 11.5 x 1000 / 26 / 18 = 98.3m )

The maximum circuit length is then the smallest of ( 2 to 4 ) Regulation . Table 4D5 . Particular interest for Domestic and Office installations
Ring-final-circuit . 2.5mm[SUP]2[/SUP] - 1.5mm[SUP]2[/SUP]

Table 4D5 . 18mV assuming ( Ib ) 32A
L.v.d. 4 x 11.5 x 1000 ÷ 32 ÷ 18 = 79.9m

( Cable doubled (2) cable length to farthest point

BS-1363 20A . 411.3.3 Ordinary persons
P/278 . BS-1363 13A plugs , socket-outlets etc 433.1.103.
P/174 . Table 55.1. Fused plugs and shuttered socket-outlets . 2-pole and earth . for A.C.

P/174 . 553.1.100.
Every socket-outlet for household and similar use shall be of the shuttered type and . for A.C. installation , shall preferably be of a type complying with BS-1363 .

Appendix 15 ( Informative )
This appendix sets out (( Options for the design )) of Ring and Radial final circuits for household and similar premises in accordance with Regulation 433.1.

P/426 . Fused connection unit ( FCU ) to BS-1363-4 . maximum fuse 13A
Junction box to BS-EN-60670-22 .
junction boxes with screw terminals must be accessible for inspection . testing & maintenance or , alternatively , use maintenance-free terminals / connections . Regulation 526.3.

 

[amberleaf]

Extracts .
Final circuit PVC (( Thermoplastic )) Sheathed cable .

Determine the cable size and suitable BS-EN-60898 circuit breaker for a 3.65kW storage heater installed in an office. The heater is to be wired in thermoplastic insulated and sheathed 6242Y cable (PVC sheathed). The circuit length is 20 metres and the cable will be in contact with thermal insulation exceeding 100mm in thickness on one side for a significant part of its run above a plasterboard ceiling

The characteristics of the supply are as follows:
Nominal Voltage = 230 volts
PFC at origin = 1.75kA
Ze at origin = 0.13 ohms

Answer
Step 1 Calculate design current ( Ib )
Total Ib =
Ib = 15.9 amps

Step 2 Select protective device ( In )
As we have seen Ib ≤ In and Ib = 15.9 amps The nearest suitable size of circuit breaker would be a 16 amp Type B from Table 41.3 (Part 4 BS-7671: 2008).
( In ) = 16 amps.

Step 3 Determine maximum disconnection time
The maximum disconnection time for compliance with 411.3.2 for a final circuit not exceeding 32A is 0.4 seconds.

Step 4 Determine correction factors
There are no correction factors applicable but the cable is directly in contact with thermal insulation exceeding 100mm in thickness on one side. This means that the only de-rating required is to choose the sheathed cable size from Table 4D5 referring to Reference Method 101 (column 3).

Step 5 Applying correction factors
No correction factors to apply.

Step 6 Select the cable size ( Iz )
It replaces ( In )
It = 16 amps From Table 4D5 (Appendix 4 BS 7671: 2008 (2011))
Reference Method 101 column 3 the nearest suitable size of thermoplastic insulated and sheathed cable (PVC sheathed) to carry 16 amps is 2.5mm² which can carry 17 amps (in this instance).

Iz = 17 amps
Cable size = 2.5mm[SUP]2 [/SUP]

Step 7 Check shock constraints
The maximum Zs value for a 16 amp Type B circuit breaker from Table 41.3 (Part 4 BS-7671: 2008 (2011)) is 2.87 ohms

Zs = 0.6 ohms where Ze = 0.13 ohms
F = 1.2 from Table 3 (Page 10) of these notes
R1 + R2 = 19.51mohms/M for 2.5/1.5mm2 cable from Table 4 (Page 20) of these notes
L = 20 metres (given in question)

which is acceptable as it is less than 2.87 ohms from Table 41.3.

Step 8 Check thermal constraints
The CPC of the thermoplastic insulated and sheathed cable (PVC sheathed) does not comply with Table 54.7 so the adiabatic equation must therefore be applied.

S = 1.05mm2
where I = Fault current
t = Disconnection time of fault current
t = 0.1s from Fig 3A4 Appendix 3 BS 7671: 2008 (2011) for 16 amp BS-EN-60898 Type B circuit breaker at 383.3 amps
k = 115 from Table 54.3 (Part 5 BS 7671: 2008(2011)) for 70°c PVC

As the CPC of the cable is 1.5mm² and the minimum CSA for thermal constraints is 1.05mm[SUP]2 [/SUP] the CPC is adequate.

Step 9 Check voltage drop
where mV = 18mV from Table 4D5 (Appendix 4 BS 7671: 2008 (2011))
Ib = 15.9 amps
L = 20 metres

VD = 5.7 volts which is acceptable as 5% of 230 volts = 11.5 volts

 

[amberleaf]

Regulation 411.4.7.
Where a circuit-breaker is used . Etc
The values specified in Table 41.3. for the types and ratings of overcurrent devices listed may be used instead of calculation .

Calculation for BS-EN-60898-1 circuit-breakers (( only ))
Type B , ( Zs ) 20A type B / C / D can be calculated , Sherlock Ohms
5 x 20 = 100
230 ÷ 100 = 2.3Ω [ 20A – 2.30 ]

Type C , ( Zs ) 10 x 20 = 200
230 ÷ 200 = 1.15Ω

Type D , ( Zs ) 20 x 20 = 400
230 ÷ 400 = 0.57Ω

( Zs ) value for a 20A Type 1 BS-3871 .
4 x 20 = 80
230 ÷ 80 = 2.87Ω

O.S.G. Table 7.2.7.(ii) P/72
Circuit-breakers BS-3871-1
Type 1 . Multiplier ( 4 )
Type 2 . Multiplier ( 7 )
Type 3 . Multiplier ( 10 )
Type 4 . Multiplier ( 20 )

 

[amberleaf]

Enhanced Fire Safety from Consumer Units

Amendment 3 to BS-7671:2008 Requirements for electrical installations ( IET Wiring Regulations ) will be published on 5[SUP]th[/SUP] January 2015 . These new and changed regulations will apply to all Electrical Installations designed after 1[SUP]st[/SUP] July 2015 * . Whilst there are many additions and changes being introduced through this amendment , it is expected that there will be specific new regulations relating to the enhancement of Fire Safety.

One particular regulation , 421.1.201. is expected to address the selection of Consumer Units in domestic ( household ) premises and , as such , introduces a new enhanced functionality to this equipment . The regulation is expected to state :

“ Within domestic ( household ) premises , consumer units and similar switchgear assemblies shall comply with BS-EN-61439-3 and shall :
(i) Have their enclosures manufactured from non-combustible material ,
Or
(ii) Be enclosed in a cabinet or enclosure constructed of non-combustible material and complying with regulation 132.12.

Note (1) : Ferrous metal e.g. steel is deemed to be an example of a non-combustible material
Note (2) : * The implementation date for this regulation is the 1[SUP]st[/SUP] January 2016 .
This does not preclude compliance with this regulation prior to this date “

The intent of regulation 421.1.201 is considered to be , as far as is reasonably practicable , to contain any fire within the (( Enclosure )) and to minimise flames from escaping , caused mainly as a result of poorly instead connections .

What is a definition of “ Non-combustible “
There is no published definition for “ Non-combustible “ that aligns with the intent of regulation 421.1.201. Ferrous metal , e.g. steel , is deemed to be one example of a non-combustible material that meets the intent of the regulation .

What constitutes a “ Non-combustible enclosure “
A non-combustible enclosure includes : Base , Cover , Door , and any components , e.g. Hinges , Covers , Screws and Catches , necessary to maintain fire containment .

Blanks and devices are contained within the non-combustible enclosure .

How is account taken of cable entries into a non-combustible enclosure “ with respect to containment of internal fire and escape of flames ?
Good workmanship and proper materials must be applied by the installer . The cable installation entry method shall , as far as is reasonably practicable, maintain the fire containment of the enclosure . Account shall be taken of the manufacturer’s instructions , if any .

What is meant by “ Similar switchgear assemblies “ ?
“ Similar switchgear assemblies “ are assemblies used for the same fundamental application as consumer-units .

Does regulation 421.1.201. apply to consumer units and similar switchgear assemblies installed in domestic ( household ) garages and outbuildings . ( Yes ) the intent of regulation 421.201. is that it applies to consumer units and similar switchgear assemblies to BS-EN-61439-3 . inside all domestic ( household ) premises including their integral / attached garages and outbuildings or those in (( close proximity ))

[h=1]Design Verification :- BS EN 61439-3:2012[/h][h=2]Low-voltage switchgear and controlgear assemblies. Distribution boards intended to be operated by ordinary persons (DBO)[/h]
Extracts form IET.
Does this mean all installed consumer units with plastic enclosures are a fire risk ?

No, provided the consumer unit and its incorporated components conform to the relevant product standard(s), do not have latent defects, and have been installed correctly to the manufacturer’s instructions.

Definition of non-combustible:

2011: P/277 :- BS-476: Part 4: 1970 Non-combustibility test for materials.
This test classifies materials as either ' non-combustible' or 'combustible '. It is the most stringent standard for the fire performance of materials and gives a measure of the heat and flames generated by the material under standard heating conditions. Non-combustible materials can be used without restriction anywhere in a building. Their use ensures that hazards due to smoke and toxic gases are " minimised " and that the fabric of a building will not make a contribution to a fire.

 

[amberleaf]

In 2012/4 253 London Fire Brigade recorded fires where a consumer unit was identified as the source of ignition.

Number of fires :
2005/06 - 27
2006/07 - 28
2007/08 - 33
2008/09 - 21
2009/10 54
2010/11 - 73
2011/12 - 71
2012/13 - 220
2013/14 - 253 ... offending CU

 

[amberleaf]

[h=1]Extracts :
Circuit breakers used as switching devices[/h]
The 17th edition introduced a quick selection table 53.4 to assist with the selection of devices used for various functions such as isolation, emergency switching and functional switching.

This table suggests that circuit breakers to BS-EN-60898-1, BS-EN-60947-2, and RCBO’s to BS-EN-61009-1 are suitable to be used as functional switches. So in a shop for instance where the lights may be either all on or all off the circuit breaker in the distribution board could be used to switch the lights on and off.

Whilst circuit breakers are suitable to switch loads of course, their primary function is as circuit protection devices and depending on the type of load they are switching may not be the best product to select for this purpose.

For this reason Amendment 3 has added a small note to this table stating:
Circuit-breakers and RCDs are primarily circuit-protective devices and, as such, they are not intended for frequent load switching. Infrequent switching of circuit-breakers on-load is admissible for the purposes of isolation or emergency switching.

For a more frequent duty, the number of operations and load characteristics according to the manufacturer’s instructions should be taken into account or an alternative device from those listed as suitable for functional switching in Table 53.4 should be employed.

So specifiers or installers should either consult the manufacturer of the circuit breaker giving information as to the type of load being switched or better still use a device listed in the table as a switching device which are designed for this frequent duty.

10th December 2014

 

[amberleaf]

Table A2 ( 1 ) Lighting . 66% of total current demand

6 - Fluorescent lamps : ( 1.8 ) P/110 - Note ( 2 )
Table A1 Lighting circuit , Current equivalent to the connected load, with a minimum of 100W per lampholder .
Assume 100W per lamp and from note (2) , multiply the lamp wattage by ( 1.8 ) I = W x 1.8 / V = 6 x 100 x 1.8 / 230 = 1080 / 230 = 4.7A

10 x 58W Single linear fluorescent lamps , 10 x 58W = 580W , multiply by 1.8 to give 1044 VA and hence 4.5A .
( contain modern HF ballasts or power factor correction )

if the ( VA ) rating of the lighting units is unknown , then use the rated wattage of the actual tubes / lamps used multiplied by ( 1.8 to arrive at an estimate of the ( VA ) rating for the lamp and ballast ) 10 x 580 , 580 x 1.8 = 1044 VA

 

[amberleaf]

Homeowners report carried out . ( EICR )
Question’s to be Asked . ??

- Never act upon the recommendations .
- Electrical Installation Condition report .. Observations ; you could probably put money on them never being touched .
- Report will never see the light of day again . (Stuck in a drawer) next time around . ( Yeah )

Electrical Installation Condition Report is not a certificate. ((Condition reporting Only )) ... satisfactory condition for continued service

Periodic Inspection & Testing
621.1. Where required , periodic inspection and testing of every electrical installation shall be carried out in accordance with Regulation 621.2. to 621.5. in order to determine , so far as is reasonably practicable , (( whether the installation is a satisfactory condition for continued service )) Wherever possible Etc.

621.2. Periodic inspection comprising a detailed examination of the installation shall be carried out without dismantling , or with partial dismantling as required , as required , supplemented by appropriate tests from Chapter 61 to show that the requirements for disconnection times , as set out in Chapter 41 for protective-devices , are complied with , to provide for : refer

 

[amberleaf]

All users of the IET Wiring Regulations need to be aware of the coming changes in Amendment No 3 to the 17[SUP]th[/SUP] Edition ( BS-7671:2008+A3:2015)
Consumer Units ( to come into effect January 2016 )

New Amendment BS-7671 : 1[SUP]st[/SUP] January 2015 . Options - for six months you can install to Amendment 2 or Amendment 3 , that means as from 1[SUP]st[/SUP] of July 2015 all electrical installation’s design to the new Amendment shall be installed to the new Amendment and certified to the third Amendment .

1[SUP]st[/SUP] July 2015 Certified :- To guarantee as meeting the standard . “ certification “

Amendment No 3 publishes on 5 January 2015 and comes into effect on 1[SUP]st[/SUP] July 2015 , All new installations from this point must comply with Amendment No 3 to BS-7671:2008

 

[amberleaf]

Appendix 3 Time/current characteristics of overcurrent protective devices and RCDs
This includes changes in connection with maximum earth fault loop impedance to take account of the Cmin factor given in CLC/TR50480:2011.

December 2012
PD CLC/TR 50480:2011
Determination of cross-sectional area of conductors and selection of protective devices

Descriptors
Electric cables, Power cables, Insulated cables, Electric conductors, Copper, Aluminium, Stranded conductors, Flexible conductors, Electric wires, Diameter, Electrical resistance, Resistance measurement, Dimensional tolerances

[h=3]‘Cmin’ factor[/h]Maximum earth fault loop impedances given in Tables 41.2, 41.3, 41.4 and 41.6 will be revised to take into account the Cmin factor given in CLC/TR50480:2011.

Cmin is the minimum voltage factor to take account of variations in voltage, depending on time and place, changing of transformer taps and other considerations. The notes to the Tables will be changed to reflect maximum permitted operating temperature. In addition, Regulations 411.5.4 and 41.6.4 will include a Cmin factor.

( Zs change every single Zs value throughout BS-7671: ( A3 ) will be changing , the new factor coming in Cmin it will reduce all exciting Zs values 0.05%

 

[amberleaf]

Installation method change ( A3 )

Escape routes :- you are not allowed to rely on plastic or non-metallic means of support , that means plastic trunking or plastic tray what you have to do , you can still use it but support it with metal fixings and make sure that it does not come down , also if you have used ( Cable Ties ) plastic tie wraps in the past , you will have to use metal tie wraps stopping the cable dropping down in the event of a fire .

 

[amberleaf]

Sticking to the theme of fire’s .

( CCU ) consumer units ( A3 )
Consumer units will have to change , what they’re saying now is ( Household ) domestic premises must be made of Non-combustible martial , to give you an example of Non-combustible martial ( Ferris metal , example Steel ) take effect on 2016

 

[amberleaf]

Changes ( A3 )
Model form’s ; electrical installation’s ( Certification )

Electrical Installation Certificate
Schedule of items Inspected, use to be a tick box with 44 boxes now it’s going to be 3 pages worth , (( Now to 120 boxes ))

 

[amberleaf]

( A3 ) They are minor changes

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

 

[amberleaf]

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.

 

[amberleaf]

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.

 

[Marvo]

.....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.

 

[amberleaf]

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.

 

[amberleaf]

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.

 

[amberleaf]

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 !!

 

[amberleaf]

( 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.

 

[amberleaf]

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

 

[amberleaf]

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.

 

[amberleaf]

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

 

[amberleaf]

( 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

 

[amberleaf]

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 .

 

[amberleaf]

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] )

 

[amberleaf]

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

 

[amberleaf]

( r[SUP]1[/SUP] & R[SUP]1[/SUP] ) r[SUP]1[/SUP] , r[SUP]2[/SUP] & r[SUP]N[/SUP] are the end-to-end ring-final-circuits readings .
R[SUP]1 [/SUP]) is the maximum measured résistance of the line-conductor for a circuit .
R[SUP]2 [/SUP]) is the maximum measured résistance of the circuit-protective-conductor for a circuit .

( R[SUP]1[/SUP] + R[SUP]2[/SUP] ) is the test reading value of the two résistance added together

 

[amberleaf]

:rant: On rant mode , regulation 421.200

100A disconnector(s) are a higher risk of overheating they carry a heavier load . (( why not improve them )) Manufactures

Main isolation disconnectors with just one-terminal screw for a 25mm[SUP]2[/SUP] cable (( cause for concern ))
We used them in the past , 2 screw terminals used for 100A ( Switches ) disconnectors , cooker switches

Has regulation 421.200 been influenced by fire safety alone !
Are plastic consumer units being blamed for other types of electrical fires !

One aspect of an installation that is rarely upgraded ( except in extreme cases ) is the electricity supply intake equipment on the DNO side of the meter
Many of the cables , connections and cut-outs have been in place and rarely touched since they were first installed up to 60 years . plus

 

[amberleaf]

(1) The safe isolation procedure .. ( You isolate to Stop )

(( Before starting ))
(2) remember to seek permission from a relevant responsible person , because there might be certain vital services that must not be interrupted at any time , There might be a permit to work system in place to which you will need to comply .

(3) Identify the point of isolation for the system or circuit , lock-off , place warning label , keep the key to the lock with yourself .
(4) Select the correct and mains approved test equipment , ensure that it works correctly by testing on the proving unit .
(5) Test the outgoing side of the means of isolation (( Main switch , circuit-breaker , fuse )) etc to make sure it is dead , (( Depending on the type of supply )) you will need to complete the following tests .
(6) Single-phase installations test to confirm that there is no voltage between :- Line and Neutral , Line and Earth , Neutral and Earth .
(7) Phase installations test to confirm that there is no voltage between , L1 & L2 , L1 & L3 , L1 and Neutral , L1 and Earth , L2 and L3 , L2 and Neutral , L2 and Earth , L3 and Neutral , L3 and Earth , Neutral and Earth .
(8) Re-test the test equipment on the proving unit .
(9) When isolating the main source of energy it is also essential to isolate any secondary sources such as ( standby generators , uninterruptible power supplies ( UPS ) and microgenerators )

Step 1 .
• Identify the point of isolation for the system or circuit . ( Electricity takes the path of least résistance )
• Lock off. ( Prevention )
• Place warning label (( Warning Electrician Working & Do Not Switch On ))
• Keep the key to the lock with yourself.

Step 2 .
• Select the correct and main approved test equipment .
• Ensure that it works correctly by testing on the proving unit.

Step 3 .
Objectives • Test the outgoing side of the mean of isolation ( Main switch , Circuit-breaker Fuse ) To make sure it is Dead .
• Depending on the type of the supply you will need to complete the following tests:
• Single-phase installations test to confirm that there is no voltage between :
Line & Neutral
Line & Earth
Neutral & Earth

• Three-phase installations test to confirm that there is no voltage between :
L1 & L2
L1 & L3
L1 & Neutral
L1 & Earth

L2 & L3
L2 & Neutral
L2 & Earth

L3 & Neutral
L3 & Earth
Neutral & Earth

Step 4 .
Re-test the test equipment on the proving unit

2394 your Q/As Safe isolation . When isolating the main source of energy it is also essential to isolate any (( Secondary sources )) such as :
- Standby generators . refer (9)

Re-cap “ The human body is a conductor “
Electricity must have a complete path . You only get one change to prove (( Safe Isolation )) Electricity flows through Conductors . Water , Metal . The Human body .

Circuit-breakers provided to protect Equipment not people .
Fuses , are designed for self destruction , under fault conditions .

 

[amberleaf]

As a Skilled person, Firstly this is a template for learning curve , Excises only . What Codes , are appropriate . ?? & recommendations’
No answers will be given “ As an Inspector “

Observation

Regulation 612.10. RCD does not operate in the required time

612.1. Unable to gain access to carry out all tests. Due to the condition and/or method of installation of the electrical equipment the inspector cannot be confident that it is safe for continued use, therefore further investigation is recommended

612.1. Unable to shut-down due to client operational limitations to carry out all tests. it is the inspector’s opinion that there is no apparent risk for continued use and therefore, as agreed with the client that this observation is categorized as a limitation ( Limit ) subject to safe isolation procedures are put in place before any maintenance on electrical equipment is carried out .

612.3.2. Low insulation résistance reading(s) recorded

612.9. Unable to shut-down due to client operational limitations to carry out earth-loop-tests , readings entered are from carrying out an ( r[SUP]2 [/SUP] ) test only , with a wandering lead fed from another live source to prove earth-continuity , therefore , unable to ascertain whether the earth-loop-impedance is low enough to operate the protective device in the required time . it is the inspectors opinion that there is no apparent risk for continued use and therefore, as agreed with the client , this observation is categorized as a limitation ( Limit ) subject to safe isolation procedures are put in place before any maintenance on electrical equipment is carried out .

612.9. Unable to gain access to carry out earth-loop-tests , readings entered are from carrying out an ( r[SUP]2 [/SUP] ) test only , with a wandering lead fed from another live source to prove earth-continuity , therefore , unable to ascertain whether the earth-loop-impedance is low enough to operate the protective device in the required time . it is the inspectors opinion that there is no apparent risk for continued use and therefore, as agreed with the client , this observation is categorized as a limitation ( Limit ) subject to safe isolation procedures are put in place before any maintenance on electrical equipment is carried out .

Regulations 612. Protective device(s) removed, unable to carry out live tests
612. Testing .

Regulation 612.6. Unable to gain access to confirm whether polarity is correct , Due to the condition of the electrical equipment and/or method of installation the inspector cannot be confident that it is safe for continued use , therefore further investigation is recommended

Regulation 612.6. Unable to shut-down due to client operational limitations to confirm whether polarity is correct , it is the inspector’s opinion that there is no apparent risk for continued use and therefore , ( As Agreed with the Client ) This observation is categorized as a limitation ( Lim ) subject to safe isolation procedures are in place before any maintenance on electrical equipment is carried out .

Regulation 612.3.1. Unable to gain access to carry out insulation résistance test(s) Due to the condition of the electrical equipment and/or method of installation the inspector carrying out this inspection cannot be confident that it is safe for continued use, therefore further investigation is recommended

Regulation 612.3.1. Unable to carry out insulation résistance test(s) due to risk to (( Electronic components on the circuit )) it is the inspectors’ opinion that there is no apparent risk for continued use and therefore , as ( Agreed with the Client ) this observation is categorized as a limitation ( Lim )

Regulation 612.2.1. & 612.9. Unable to gain access to confirm whether the protective conductor is ( Continuous throughout circuit(s) Due to the conditions of the electrical equipment and/or method of installation the inspector cannot be (( Confident that it is safe for continued Use )) therefore further investigation is recommended

Regulation 612.2.1. & 612.9. Unable to shut-down due to ( Client ) operational limitations to confirm whether the protective-conductor is continuous throughout circuit(s) therefore unable to carry out an earth-loop-impedance test(s) it is the inspectors’ opinion that is no apparent risk for continued use and therefore, as (( Agreed with the Client )) this observation is categorized as a limitation ( LIM ) subject to safe isolation procedures’ are in place before any maintenance on electrical equipment is carried out .

Regulation 612.9. Unable to gain access to carry out earth-loop tests . Due to the condition of the electrical equipment and/or method of installation the inspector cannot be confident that it is safe for continued use, therefore further investigation is recommended

Regulation 612.9. Unable to shut-down due to client operational limitations to carry out earth-loop tests, it is the inspectors’ opinion that there is no apparent risk for continued use and therefore, as agreed with the client , this observation is categorized as a limitation ( LIM ) ) subject to safe isolation procedures’ are in place before any maintenance on electrical equipment is carried out .

 

[amberleaf]

My own Option
You don't put a round peg in a square hole, however it would seem no one taught the manufacturers ? ( CCU ) 25mm[SUP]2[/SUP] Tails

 

[amberleaf]

Periodic Inspection & Testing . You.re Q , is it fit for Continuous Use .

Re-cap , Scope : GN-3
it is essential that the inspector and the person ordering the inspection agree the extent of the installation to be inspected beforehand, and any criteria regarding the limit of the inspection. The details should be recorded on the Certificate .

Regulation 612.8.1. Unable to gain access to verify all details of the protective device. Due to the condition of the electrical equipment and/or method of installation the inspector cannot be confident that it is safe for continued use, therefore further investigation is recommended

Regulation 612.8.1. Unable to shut-down to client operational limitations to gain access to verify all details of the protective device. it is the inspectors’ opinion that there is no apparent risk for continued use and therefore, as agreed with the client, this observation is categorized as a limitation ( LIM )

 

[amberleaf]

Regulation 612.2.2.
(( Continuity )) A test shall be made to (( Verify the continuity of each conductor )) including the protective-conductor, of every ring final circuit .

Regulation 612.2.2.
Continuity reading high on ring-final-circuit ( R[SUP]2[/SUP] ) suspect loose termination or broken ring-connection . You.re call As a Inspector

 

[amberleaf]

Regulation 612.2.2.
(( Continuity )) A test shall be made to (( Verify the continuity of each conductor )) including the protective-conductor, of every ring final circuit .

Regulation 612.2.2.
Continuity reading high on ring-final-circuit ( R[SUP]2[/SUP] ) suspect loose termination or broken ring-connection . You.re call , As a Inspector

514.9.1. Circuit(s) description missing / no circuit chart , unable to trace circuit(s) therefore unable to carry out test(s)
514.9.1. Circuit(s) description incorrect , unable to trace circuit|(s) therefore unable to carry out test(s)
612.8.1. Details of the protective device missing or not visible , therefore unable to test for compliance ?

 

[amberleaf]

612.1. Unable to gain access to carry out full testing due to the presence of ( Asbestos ) Due to the condition of the electrical equipment and/or method of installation the inspector cannot be confident that it is safe for continued use, therefore further investigation is recommended .

612.1. Unable to shut-down due to client operational limitations to carry all tests, it is the inspectors’ opinion that there is no apparent risk and therefore, as agreed with the client , this observation is categorized as a limitation ( LIM ) subject to safe isolation procedures are in place before any maintenance on electrical equipment is carried out .

 

[amberleaf]

Unable to gain access to verify type and size of (( DNO fuse )) 612.1.

612.6. Polarity incorrect .
612.10. RCBO does not operate in the required time .
612.10. Time delay on RCBO operating in a time exceeding the setting of the device .
415.1.1. Where an RCBO has been installed and is used for additional-protection the RCBO failed to operate at less or equal to 40mS at a residual current of 5 IΔn