However the consumer unit has no spare fuse ways and there is no RCD protection on the top floor circuit. Therefore I would have to buy a separate consumer unit for the shower and split the incoming 16mm cable so that I can feed both the original unit and the new shower consumer unit.
I’ve had a look around and I think the following items would work.
For splitting the cable: http://www.allaboutelectrics.co.uk/60a-3-terminal-junction-box.html
For the consumer unit: http://www.allaboutelectrics.co.uk/combined-rcbo-shower-unit-40a.html
I assume that I would then need to run either 6mm or 10mm cable to the shower. The length of the run from the new unit to the shower, via an isolator pull cord switch, would only be about 5m.
As to earth bonding in the bathroom the only metal is the pipes so they are the only items that need to be bonded.
I would be grateful if anybody can confirm that this is all OK and whether there is any cheaper/easy alternatives with regard the consumer unit and junction box.
I am aware of part P but having installed two showers in the past feel competent enough to do it.