DIY Doctor UK DIY Forums

Hi,

I purchased a new dimmer switch (metal plate) and wanted to install it replacing my existing standard white plastic switch. I noticed that I only have two wires coming out of the wall a red and black but no bare "earth" wire ??

When investigating other boxes I noticed that all have a bare copper wire connected to the metal box in the wall, this box didn't for some reason. I believe it is hidden somewhere under the plaster.

My new dimmer switch has an earth wire. Should I simply connect this to the metal box in the wall or do I need the bare "earth" copper wire for it to be earthed correctly ?? i.e. does connecting the earth wire of the dimmer switch to the metal box in the wall mean it is earthed ??

I hope I haven't confused you.

No it won't do at all, the box although metal in a dry wall won't be earthed properly so if your dimmer goes faulty (which they often do) the front plate can become live & fuse/mcb won't blow/trip, the first time you will know it's live is as you slide down the wall in your death throes......
It might be a bit of a nuisance but find & connect the earth wire even if it means cutting the box out and raising it an inch or two to gain wire to connect to, bet you just decorated too.....sorry,
regards SPARX