How do I earth my dimmer switch?

[varez]

Hi,

I am replacing my standard switch with a chrome 2-way dimmer switch, and was advised that I have to earth it.
Inside the mounting box I only see too wires - one for C and one for L1, so I'm not sure what to do with the earth terminal on the dimmer switch.
Is it dangerous not to earth it?

Thanks!

 

[varez]

I just noticed that there is a third wire (yellow/green), but it is attached into a hole in the mounting box. Is this the earth wire?

 

[breezer]

10 out of 10

you run a 1mm green yellow wire from that to the earth terminal on your switch

 

[dingbat]

Actually, you attach the circuit cable to the switch. You may then, additionally, run a link to the back box earth terminal, but the most important thing is that the switch body is directly connected to the circuit's earth conductor (known as the circuit protective conductor, or CPC).