8.3 indicates 8.3kW or 8,300 Watts
An 8.3kW shower will draw 36Amps so your wires and circuit breaker need to be capable of handling this.
An 8.5kW shower 37 Amps and 9.5kW just over 41 Amps
If you need to change the wiring and install a new circuit then the Building Regulations call for a certified electrician to do the work I believe...
http://www.diydoctor.org.uk/projects/partp.htm
Peccavi
March 2010
howtomendit.com for free repair help, information and advice.
