Please don't bite, im just after some advice prior to getting the work done, so I know what it entails. My main consumer unit in my house is old, I have had an electrician look at it before and he said upgrading it was a big job. The house is old, three storey's and has masses of cables. He said if one of the circuits wasn't earthed right then the RCD would just flip. From this, I have an armored cable which runs into another smaller old unit which is situated in my garage. My wife wants me to convert the garage so she can run a business from there. The unit in the garage is currently has two fuses, one for lights and one for sockets. There is one free. It is connected to the unit in the house with a 30amp fuse. My wife want to use a shower in the garage, this would require a 40amp fuse with RCD. Would I be looking at running another cable from the house straight to the shower unit; or; Could I upgrade the 30amp fuse on the main circuit board which feeds the garage and then use the free slot on the garage unit? I do have a new consumer unit which is sat nothing, would it be best to use this in the garage? Any advice welcome.