On Thu, 08 Oct 2009 16:44:31 GMT, "ARWadsworth"
wrote:

The limit is not a total sum of the MCBs in the CU. If it was then most
houses would blow the main fuse if you added up all the MCB ratings!

You are quite right, I would be unlikely to be pulling 32A through the
sockets and 6A through the lights at the same time, so I do not need
to worry about the MCBs added together: diversity and all that. I
guess if someone fitted too many 500W PIRs the 6A MCB could trip but I
don't use 500W PIRs myself so that won't be a problem for us.

There is no point putting your freezer on its own supply if the incoming supply is
protected by an RCBO.

Oops. I forgot I was in the garage, but on the house CU it is a good
idea to have a separate freezer ring.

As I am a lazy sod I often wire garage sockets using a 4mm radial setup with
a 32A MCB instead of a ring.

If it was a workshop with dozens of sockets I would use a ring but it
isn't and I may just have two sockets. I wonder about using a radial.
I was going to use 2.5mm T&E and a 16A MCB, though I note your
previous comments about certain appliances wanting a 32A MCB.

Other options are to use 10mm T&E for the supply or use armoured cable if
you really want a bigger supply.

I don't think armoured is necessary as it's not overhead or
underground. I agree 10mm would give more capacity but I think I
already have some 6mm, hence I was going to use that. I am sure 40A is
more than I could need.

Thanks again.