connecting CPC between socket and light circuit
- Thread starter AndyPRK
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2 separate circuits in the same box is not unusual - 1 for a lamp separately switched, 1 for a phone charger or whatever else. Many hotels have similar.
Or a socket outlet and 1g light switch either side of the bed. Or a lamp outlet and a single socket for the kettle.
2 circuits with connected CPCs is not unusual either - happens all the time.
Upstairs/downstairs lighting circuits with a 2g switch in the hall.
Immersion heater and gas boiler which are connected via the pipework.
Bathrooms which have supplementary bonding.
Installations done entirely in steel conduit.
Or a socket outlet and 1g light switch either side of the bed. Or a lamp outlet and a single socket for the kettle.
2 circuits with connected CPCs is not unusual either - happens all the time.
Upstairs/downstairs lighting circuits with a 2g switch in the hall.
Immersion heater and gas boiler which are connected via the pipework.
Bathrooms which have supplementary bonding.
Installations done entirely in steel conduit.
What makes you say that?
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Have them both powered from the socket circuit, but one of them switched by a contactor operated by the light switch.
How (unnecessarily) complicated! As has been said, connections between CPCs of different circuits are common - and, indeed, if everything is in steel conduit (all the way back to CU/DB) then the CPCs of all circuits will be connected.
Furthermore, although, as has been said, care in required with testing, having interconnected CPCs actually provides a degree of CPC redundancy and, in the absence of faults, a greater effective CPC CSA for all the 'joined' circuits.
WE do commercial kitchens there could be numerous circuits, fans, lights, sockets, isolaters, all connected by there metal boxes etc to a steel canopy splash-back, therefore linking all the earths.
I have dual boxes at home with metal fronts, 5 amp socket via a dimmer and a switched 5 amp on a separate radial circuit, i just put each earth in its own separate face plate terminal and strapped just the higher rated front to the backbox, regardless of the metal box linking the fronts , so its likely evident to anyone doing an R1 R2 measurement.
As for other testing as Johnw says its no different to Earth loop testing an older bathroom or commercial kitchen with supplementary bonding, which was offten tagged into a socket outlet, no one Afaik removed the bonding to loop test
I have dual boxes at home with metal fronts, 5 amp socket via a dimmer and a switched 5 amp on a separate radial circuit, i just put each earth in its own separate face plate terminal and strapped just the higher rated front to the backbox, regardless of the metal box linking the fronts , so its likely evident to anyone doing an R1 R2 measurement.
As for other testing as Johnw says its no different to Earth loop testing an older bathroom or commercial kitchen with supplementary bonding, which was offten tagged into a socket outlet, no one Afaik removed the bonding to loop test
It was a suggestion more aimed at not having a socket on a lighting circuit than the cpc issue. NB I'd missed that it was going to be a BS 546
As has often been pointed out in the past, even if it were to be a BS1363 socket, the regs explicitly allow that on a lighting circuit.
They do.
There is the question of elegance.
There is the question of elegance.
Not just elegance in this case, also practicality. If there were two identical looking BS1363 outlets side-by-side, one on a sockets circuit and the other a switched feed from a lighting circuit, not only might someone 'plug their vacuum cleaner into' the latter, but, whatever they plugged in, they might get confused by the fact that it wouldn't work unless the lights were switched on! As always, one could address that by 'labelling', but that would probably not be particularly 'elegant'.
I don't think I'll be using a contactor to switch about 10W of LEDs
I don't think that would be elegant!
I don't think that would be elegant!
I suppose that depends on what one regards as elegant but, as I said, it would certainly be unnecessary, and unnecessarily complicated. If you really wanted to get him going, I suppose you could have that lighting socket controlled by a smart phone (which I doubt he would regard as elegant)
Kind Regards, John
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