supply upgrade required?

[sparky666]

Hi, i need to add a sub main to an existing supply for a second cu from which i will wire the extension, an out building and a barn. The existing supply is 100a and protected by a 100a 1361 fuse at the incoming service head.

This supplies the main cu which has the following circuits:

Shower 32a

ring 32a

cooker 32a

radial socket 16a

lights 6a

lights 6a



I calculate the maximum demand as 80a.



I propose to split the tails via henly blocks into a swith fuse and then supply my second cu with swa.



This will then supply:

extension ring 32a

extension lights 6a

out building sub main 32a

barn sub main 45a



outbuilding will have its own cu with:

Sockets radial 20a

lights 6a



barn will have its own cu:

sockets radial 20a

lights 6a

i will wire sub mains as follows: switch fuse-- 16mm swa --second cu -- 6mm swa-- outbuilding

-- 10mm swa -- barn



The maximum load on all circuits should not be more than about 10kw.



Im not sure wether the main supply at the house will need upgrading or main fuse upgrading or wether it is ok as it is? Can anybody please advise? Thankyou!

 

[malcolmsanford]

With Diversity I would have made your load in the main house 49-50 amps and expect that to be on the high side.

What is going out to that barn that you envisage a 45amp load and the same for the out building why a 42amp load ??

Is there a reason you are wanting to feed the Barn/out building via your sub board.

I assume with your cable calcs you have taken in VD etc.

 

[Rockingit]

The maximum load on all circuits should not be more than about 10kw.

So, that's about 40-45 amps, then.

Why are you worrying?

 

[somersetsparks]

I wouldn't honestly worry mate, What can you suggest? new supply at a likely cost of 10K? If theres no more people in the place there probably wont be any extra load.
I have seen whole small dairy farms happily running on a 100A Single phase supply!