Borrowing a CPC

[ash_s3]

Customer has a 10 Year old loft conversion, the 'spark' that wired it has cut all the CPCs out of the T+E at all points on lighting.
Customer wants metal class 1 fitting installed.

Rest of house has earthed fitting etc its just the loft conversion thats dodgey.
Firstly im going to try and through crimp onto the CPC in the twin that feeds the loft conversion and hope its been terminated at the point where theyve taken it from.
Failing that can i 'borrow' an earth from a local socket or the shower circuit behind the wall? Was going to use a 4mm2 single core green and yellow as the BGB says it has to be 4mm2 if mechanically unprotected.


I realise its not ideal but customer doesnt want carpets/floor boards ripped up and cables chased etc..

Any help would be appreciated.

Cheers

 

[Darkwood]

No you cant borrow an earth deffo' not, consider a future change in circuits where the circuit you borrow earth from is altered, disconnected or removed - then effectively you could have lost the earthing to the loft without even knowing, circuit earthing is to be used only to protect the circuit its been installed for.

 

[needasparks]

thats mad when you think it was only ten years ago, have seen loads of this on alterations made by diy but never on a whole extension yet.

My first thoughts would be no to borrowing an earth for the list of reasons that i know someone will now put up so I would just try to rescue the existing by doing small damage where you have to. But others may disagree.

 

[ash_s3]

Yeah i totally agree, i had thought about future changes could lose the earth on the metal fitting, i was thinking of labeling the consumer unit with a traffolyte label screwed to the cover.

Hopefully i can get to the CPC thats been cut off and hope its terminated the other end.

 

[1shortcircuit]

Can you?

Find out where the first leg enters and ensure that the cpc is there and test by linking line and cpc at the board?

If so, you may only have to make a small chase above each fitting thus reducing damage (enough to crimp onto). If they don't go for it then label the consumer unit with the relevant label and tell them that they can only have class II fittings

Have you checked to see if you can pull cable through capping/conduit? May be more appropriate to rewire the circuit this way if possible?

 

[One_of_them]

another vote for the no no but...

Was going to use a 4mm2 single core green and yellow as the BGB says it has to be 4mm2 if mechanically unprotected.

why? surely this is for supp bonding? unless im on wrong page :dozey:

 

[ash_s3]

Cheers, theres a very small loft hatch you can just about get your head and one arm in! no room to get up there so i cant see where the cable comes from. Its just a pendant at the moment, im hoping theyve come off the 1st floor lights at a light fitting so i can make off the end of the CPC and not from a JB under the floor. no chance of getting the floor up as theres next to no floor space as it is.

I can see a few cables from the hatch, one comes from the fitting and drops down the wall to the switch (feed and s/w), the first leg disappears under insulation etc.. so its hard to guess where theyve taken it from.

 

[trev]

My first thought was to post "Yeah it'll be fine yyyyyeeeeehhhaaaahhh" but then I remembered it's a public forum and I have to at least appear to be a grown up.
"Borrowing" a CPC is a big no no mate, is there no way of running a 4mm through what's going to be the floor of a loft to a bathroom cupboard then in trunking to the CU?