"Andy Wade" wrote in message
...
RzB wrote:

"RzB" wrote in message
...

---- snip

It's better not to, especially as you're really looking at a 50 or 60/63
amp distribution circuit for the workshop. The problem with cascading
MCBs can be lack of discrimination on s/c faults - both MCBs may trip.
(This may not matter to you though, as you've got a separate feed for
lighting.) You also need to consider whether the house CU and indeed the
supply is OK for ~45 A of extra load. (Any electric showers or space
heating in the house?)

Ahh,... Now I just hadn't even thought about the
total current coming in to the house. That would
have popped up when I looked at diversity for the
house as part on the new CU work. Hmmm... What
happens if the calcs come out over 100A? Do I just
ask the suppliers for "more please" ! Hmm... We have
a shower - only used very occasionally by visitors so
probably not a big deal. But it will probably blow the
diversity calcs. Hmm...

------- snip

CPC is 6 mm^2. Yes, 16 mm^2 for the cable sounds about right, it'll give
you plenty of current rating in hand and keeps the voltage drop down to
2%. A separate parallel 10 or 16 mm^2 CPC would be prudent, although I
haven't done the calculations to see whether it is strictly necessary -
this depends on your choice of overcurrent device at the house end in any
case.


Yes - I need to redo the calcs but I believe the 6mm
CPC will be OK if I have a Type B in the house.
I think I would still run a separate CPC though.
However I can see that your suggestion of a fuse
is preferable. I need to redo the calcs for this. I
would imagine 6mm would not be enough for this.

Many thanks,
Roy