I am considering fitting a mirror demisting pad behind the mirrored glass door of the vanity cabinet above the sink in the bathroom. This would get power from the light switch which is the pull cord type located on the ceiling.

Someone has said I need to have an RCD in the supply to the demister as the vanity cabinet is 18" above the sink.

Two queries is I may....

1. Is the RCD really necessary?
2. If yes, then will an RCD need to have an earth wire as the supply from the lighting circuit will be live and neutral only.

Thanks for your help.

Yvonne