hi , in have a hager consumer unit ( 100A ) , mcb,s include 1x32A for cooker , 1x40A for shower - ( not used ) , 2x10A for lighting , 2x32A for sockets ( upstairs/downstairs ) , 1x20A for garage sockets , there are 3 blanks where i assume extra mcb,s can be added , i am looking to add 1x32A mcb for garden sockets , 1x32A for conservatory sockets & 1x32A for hot tub connection , can someone please tell me if this is ok ? , will main consumer unit handle this load ? , any advice would be greatly appreciated , thanks

spuddie, June 2009

A 32 Amp mcb seems a bit high for a sockets in a conservatory. 20 A would be plenty. There is no point in providing overcurrent protection (which is what an mcb does) rated at far above the safe rated current of whatever devices are going to be supplied by that circuit. Ideally the mcb should be rated at only slightly higher than the normal expected max current. Those sockets and the hot tub circuit need to be protected by the RCD as well - i.e. their neutrals should be separated from the lighting circuit neutrals etc.

J, June 2009

That sounds like it should be ok, but it depends on how much current you are drawing from each circuit at any one time. If you add all the breaker ratings together it exceeds 100A, but I assume you aren't using the full 10A on each lighting circuit, and you wouldn't for example use the hot tub, cooker, all the garage sockets and have all the lights on at the same time.

Adam, June 2009

Your consumer unit will handle the extra MCB's, no problem. However, you are restricted to the amount of current you can use by the electricity boards main fuse, usually around 60 Amp. So, it doesn't matter how many MCB's you have, as it is assumed that you won't be drawing to the maximum current at any one time.

John, June 2009