EICR - main earth and neutral

Sparkingchip:

davezawadi (David Stone):

Another example. Now discuss if this is permitted because I won't.

You have already discussed it and the answer isn’t clear cut.

https://communities.theiet.org/discussions/viewtopic/1037/25616


I asked where the meter is with the intention of trying to determine if the cable should be classified as suppliers equipment or part of the consumers installation, the next question is what fuses are installed to protect this cable, is protected by the suppliers fuse or a fuse within the consumers installation?

It depends on whether the cable is owned by the BNO or the consumer - quite possibly the BNO in which case effectively not the consumer's equipment.

gkenyon:


It's entirely possible (and perhaps more likely) that a line to neutral or line to earth fault will only short line to a single strand of the neutral or earth (or perhaps a few strands).

 

davezawadi (David Stone):

Another example. Now discuss if this is permitted because I won't.


 

No, not on the consumers side. Yes on the DNO side. ?

Sparkingchip:

gkenyon:


It's entirely possible (and perhaps more likely) that a line to neutral or line to earth fault will only short line to a single strand of the neutral or earth (or perhaps a few strands).

 

A highly likely scenario is that a carpenter fires a nail from a nail gun into a concealed cable, it would almost certainly only contact two of the neutral conductors and the whole of the live conductor, bear in mind there’s possibly nineteen neutral conductors so that gives an effective neutral of say 2.6 mm.

 

Agreed - and yes, it depends on the makeup as to the actual number and csa of the N conductors. Sounds like possibly 35 sq mm rather than the 25 sq mm example I ran through?

davezawadi (David Stone):

Which page of BS7671 permits split con on the consumer's side of the meter, or under BS7671 at all? It is probably not dangerous but is not protected, the sheath does not provide much mechanical protection to the very weak N insulation, terminating the centre aluminium conductor may be difficult because of corrosion/bimettalic consideration etc. I can find no reference to BS7870 in BS7671.

Chapter 52 does not mandate any particular list of standards for cables. Not all possible cable types are listed in BS 7671 - and even the tables that are provided don't have enough information to fully design with all of the cable types listed (e.g. armour CSA for SWA types, unusual installation methods such as sheathed cables in conduit, etc.).


At least this has a British Standard for the cable construction, so there should be no issue there ... provided it meets CPR fire performance requirements ?


So, provided it's deemed to meet the external influences requirements (some examples you've stated, perhaps), there should be no problem ... but as John says this may be BNO and outside the scope of BS 7671 as it's possibly distributor's equipment ?