On 10/03/2018 10:17, ARW wrote:
On 09/03/2018 20:33, Tim Watts wrote:
On 09/03/18 19:24, ARW wrote:
On 09/03/2018 11:29, Tim Watts wrote:
On 09/03/18 05:42, SteveE wrote:

I think I'll take this approach as it will be as easy as just taking a
single earth wire down.


You could legitimately take a single earth to the nearest light on
the same circuit that does have an earth. For this, it would be
preferable to use a single insulated earth wire with green/yellow
insulation. Often called "singles" and available from all good
electrical wholesalers (some like TLC should be able to sell a
length rather than a reel).

I don't have the regs to hand so not 100% sure if a CPC (earth) in
this scenario *must* be insulated, but it shows the purpose clearly
which is worthwhile.


It's worse than that. It would have to be 4mm green/yellow

Is that coming from the same rules that govern the size of a lone
earth rod conductor (mechanical strength)?



543.1.1 The cross-sectional area of every protective conductor SNIP
If the protective conductor
(iii) is not an integral part of a cable, or
(iv) is not formed by conduit, ducting or trunking, or
(v) is not contained in an enclosure formed by a wiring system.

the cross-sectional area shall not be less than 2.5mm^2 copper
equivalent if protection against mechanical damage is provided, and
4mm^2 copper equivalent if mechanical damage is not provided

So it doesn't specify it has to follow the cable run of the live conductor?

and follow the route/cable run of the live conductor unless that
circuit is RCD protected.

I wouldn't even know where to start looking that one up!

543.6.1 Where overcurrent protective devices are used for fault
protection, the protective conductor shall be incorporated in the same
wiring system as the live conductors or in their immediate proximity

Is a wiring system in this case the 'whole house'?