Cu upgrade

lurch · Jul 2, 2009

All

I have just completed a CU upgrade. I wont talk about the borrwoed neutral between the up and down lights!!! However, the lighting circuits, although in pvc do not have a cpc. I have advised the customer and given him a price to re-wire the lights, which he says will accept but is not in the positio to proceed at this stage. There fore I have been unable to measure the R2 and Earth loop impedance on the lighting circuits (cos there aint one!!) Any way I am in the process of completing the EIC and will clearly document the fact that there is no earth present for the lighting circuits and this is a limitation. Can some one advise if there is gonna be any come back with inspection body if this is inspected before the lights get re-wired?

Thx in advance.

Lurch

not clever · Jul 2, 2009

Take a look at the niceic best practice guides...
Best Practice Guide - Approved contractor scheme - NICEIC Group

One is about cu changes where lighting circuits are devoid of cpc.

Hope you removed all class 1 light fittings & switches & applied a label stating no cpc on the circuit.

As for the borrowed neutral, did you find that on the 2way switching stair lighting?......a common occurrence

from days gone by.

lurch · Jul 2, 2009

Fortunately I have come across the borrowd neutral scenario before and went straight to it !! Thanks for the link. . . . very useful.

Spudnik · Jul 2, 2009

Please do make sure sure you read the BPG thoroughly as it does state "A disclaimer does not absolve the installer from responsibility".

It does also give you guidance on a number of things that you must do when in this situation, even if they have verbally agreed to have the work carried out at a later date.

YTSOxford · Jul 2, 2009

Thanks for the useful link. I too am having to deal with a lighting circuit with noCPC going back to the board, although some of the switch drops do have a CPC, but they are just left loose in the pendants. AND all the pendants are metal fittings.

I have convinced him that it needs work done on it to make it safe, but was wondering whether it is possible to run a single core green and yellow to some of the pendants, instead of a complete rewire. thanks.

lurch · Jul 2, 2009

I do believe single core earth wire is acceptable.

YTSOxford · Jul 2, 2009

Thanks lurch. I have seen it done before, just needed to check before I go ahead with it.

welsh spark · Jul 2, 2009

I came across the same thing last week Just make sure you have no metal fittings ie only class 2 fittings you will need to label the circuits with no cpcs on the dis board and write on your installation cert that there are no cpcs pressent on lights and you will be fine. There is a gidance note on the elecsa web site on this well worth a look. hope this helps Alan

andekoch · Jul 2, 2009

From memory it was the 13th edition of BS7671 that did not require a CPC to the lights. As said before a separate CPC can be run without a complete rewire.

Note that when removing all metal stuff the screws that screw the switch plate onto the knockout box are metal and the knockout box is metal so either;
a) insert plastic plugs over the screws or
b) replace the switch plates with ones that come with plastic covers (eg Ultimate from TLC) or
c) go surface mount with plastic boxes or d) find knockout boxes with plastic screw inserts.

This is a good reason for additional protection from an RCD.

Also in my humble opinion the class II is far more important on the switch end (ie things that ger touched) than the light end. Also some 'double insulated' lights have metallic bits but are fine since 'double insulated'.