Adding CPC to lighting circuit.

[sjm]

Hi Guys, you're opinions would be greatly appreciated.

When adding a seperate CPC to an old lighting circuit how would you do it.
Do you think that it would be OK to attach a CPC to another circuit, perhaps Shower or ring main at a point remote from the MET in the CU, ie in the loft?
Or should the CPC conductor come from the CU?

Many thanks in advance guys.
Steve.

 

[electricsrule]

The CPC should be run and terminated into the CU onto the earth bar.

 

[telectrix]

agreed, and should, wherever possible , run with the existing twin cable.

 

[Des 56]

and size matters

 

[sjm]

Thanks guys.
This is pretty much what I thought, but the previous contractors rewired most of upstairs lights with T+E then used the supplementary bonding from shower circuit to provide the earth path. They have also connected the downstairs lights CPC to the ring main CPC to provide an earth path there. This was only done in 2009 as remedial work following a PIR, so you do wonder what they were thinking.
I guess the fact that the test/inspect interval was given as 10 years not 5 should have made me wonder about their approach/knowledge/ability, before I even tested anything.

 

[Inteificio]

Seems a bit dodgy, but never been to a site yet where I did not consider something dodgy.

 

[nickblake]

the way i look at it if you are able to run a seperate earth to the fittings you might just as well replace the existing cables almost as much work