Im changing my metal dimmer switches & twin sockets to white plastic. Im only changing the face plate (back boxes are metal). On the metal plate there is an earth cable attached but there is no where to put it on the new plastic ones. Someone has said i need to attach it the the metal back box, How? someone else has told me to just leave it as its not needed on a plastic face plate. Can someone clarify is any of the above methods are legit!? Thanks
Not needed on the plastic plate. But do keep the incoming earth wire connected to your back box - just remove the extra short bit which used to go to your old metal switch.
Most back boxes will have an earth terminal, but older ones may not. These would have been installed in the days of no earth in lighting circuits. Quite often find them in installs that have been rewired.
If the back box doesn't have an earth lug/term then run cpc/cpc's into Wago or term block (don't forget green /yellow sleeve on cpc/s and drill hole in t'backbox and self tap a flyer from said wit eye lug. This effectively earths the backbox which in this particular instance cannot be achieved wit t'plate. Reg are regs at the end of t'day..sorry but that's the way it is tbqh.
Forget the Wago and terminal block. Crimp a lug to the earth cable then terminate under an appropriate screw. Kind regards BS
No earth on the box it comes under fault conditions the exposed screws can become live and you have a potential hazard............. Bazza wins
Perhaps it is a steel conduit installation where the conduit is being used as the cpc. Therefore there would be no core to connect to the backbox other than for the socket outlets.
Recently I have found, on two occasions, a flying earth on to the earth terminal in a white surface box. Der!