Metal faceplate with plastic mounting box?

[japanesebob]

I have put up a chandelier in our front room with 9 60watt candle bulbs and I want to install a dimmer switch as it isvery bright. I understand that I either need a 600w rated dimmer, or I need to use 40w bulbs for a 400w dimmer.
The problem I have is that the dimmer I want to install is brass, but the mounting box is plastic. The dimmer has an earthing terminal, and all the advice I have read says the earth wire should be connecting first to the faceplate and then a piece of earth wire needs to run form the faceplate to the earth terminal on the mounting box- but my plastic mounting box doesnt hae anywhere for the wire to connect to. Its a new build apartment (3 years old) and all the light switches and mounting boxes are currently plastic. If I want to install the brass dimmer is it suffucient to run the earth to the faceplate, or do I need to install a metal mounting box?

 

[rebuke]

That's fine - the reason that normally you run a wire to the backbox is to earth the backbox, but as it's plastic it doesn't need it, so as long as the earth goes in to the faceplate that's all that's required...