sub mains board?

[hawkomontana]

Good day all!

my mate has asked me to install a new sub mains directly below the main cicuit board because he only has 1 way left in the original board.

In the sub mains board he requires a double oven rated at 10kw on a 40A breaker, a single oven rated at 9kw on a 40A breaker and a hob rated at 7kw on a 32A breaker all on there own individual circuits

My question is what size MCB do i need in the main board to feed the sub board?

cheers lads!

 

[telectrix]

don't feed from MCB in main board, split tails in henly blocks so you are feeding your new board direct from the meter, in parallel with the main board. your new board and tails will then be protected by the DNO's 1361 fuse. don't forget to fit RCD in your new board!

 

[cagedanimal2010]

agree with telectrix

 

[telectrix]

applying diversity for cookers, to nearest round figure, your load capacity is approx. 58A. hate to have to pay your mate's elec. bill. is he gordon ramsay?

 

[hawkomontana]

I was gonna do it with new tails fae a couple of neutral block spliters but my mate has already bought all the material and he just wants it done in the same manner as the 1 he has for his garage socket and light?

 

[hawkomontana]

Haha i know, he's just got the new kitchen and its a total beast, Got the same calculations for diversity.

What size RCD should i go with? because he doesn't know if he will add anymore circuits to the remaining 2 ways left in the sub board (5 way sub)

 

[telectrix]

100A 30mA RCD. do the job right, not how your mate says do it. you're the expert. if anything goes wrong, it's your head on the block, not his.!!!!!

 

[not clever]

you're the expert.

Not meaning to pick on or be-little anybody but are you sure? some of the question & knowledge on how to do this task seem to be a tad on the basic side if you ask me.

What size RCD should i go with
What size MCB do i need in the main board to feed the sub board

 

[Sintra]

Have you checked that any existing electrical equipment including the incoming supply is adequate for the proposed addition or alteration. 131.8