We have a electrician coming in next week to update our electric fuse boxes,he's given a quote which I am more than happy with. I have run in a new shower cable for a 10.8 kw shower which he will connect up. He did say that he would have to run a new earth cable from the new consumer unit to the cold water main under the sink. As usual its no were near the consumer unit and in order to save him time lifting floorboards,carpets etc I am going to run the cable before he comes. I am not to sure on cable size for the earth,is it 9mm, I won't do any connections,but can't see a problem putting the cable in myself.