Be very careful with water and electrics they don't mix well.
I think you will find under the Governments new law that came in to force last week or the one before, governing electrical installations, make it illegal for you to work on or replace the shower without first contacting the local authority. Check with your local town hall under building regulations (I think) they will put you right. It really is job for the professionals you only live once
Bob
BOB
January 2005