GaryMo, fair enough, point taken.
Answer me one question, if the OP had said he wanted to install this shower, what cable would you advise him for the 3 metre run?
http://www.alertelectrical.com/Elec...ectric-Shower-Satin-Chrome-D62127.asp[/QUOTE]
From the MI.....
"
The electrical installation must comply with the “Requirements for Electrical Installations” (commonly referred to as the IEE Wiring Regulations), or any particular regulations and practices, specified by the local electricity supply company in force at the time of installation. The installation should be carried out by an electrician or contractor who is registered, or is a member of, an association such as:
National Inspection Council for Electrical Installation and Contracting (NICEIC), throughout the UK
The Electrical Contractors Association (ECA), England and Wales
The Electrical Contractors Association of Scotland (ECAS)
"
Personally I would have advised the OP that if he doesn't know what cable size to use he/she is not competent to install it, and its not a suitable DIY job. It strikes me odd that the OP
is aware of the thermal insulation derating issue as most "laymen" would not consider it..