Cooker + Hob

[walec]

Hello all,

Need a little help here, never done seperate hob an Oven before.
Just been asked to look at a job for a friends Dad who was brought a ground floor flat.
He has taken out his old cooker and wants to replace it with a seperate Oven and Hob.
Oven - 2.1KW
Hob - 6.6KW
It is fed by to a cooker switch with 6mm cable with a 30A breaker (board is early 80`s)

If I feed from the cooker switch (no socket) to a JB can I connect both?
The Hob pulls 28A and the Oven 9A, Thats 37A on full load, working out diversity its 28A.
So I am thinking should I spur off the kitchen ring for the oven with a 13A plug or fused spur.

As he also wants to replace his shower and change a shaving socket to a light over the sink
I have suggested a new board with RCD as there is no RCD at present but he says he can not
afford it. I am going to have to put a seperate RCD in here anyway, special location etc.
There is little room to do much beacuse of all the storage heating controls. All hidden in a broom
cupboard.

Any help much appreciated

 

[walec]

Popped back today to look into this one further. Cable to the oven is 10mm not the 6mm I previously quoted, so apologies to all I should have looked closer! and thanks for replying.
So I will add a socket at the connection point behind the oven.

The problem now is with the bathroom, the customer wants to move the existing shaver socket and replace it with a shaver socket and light unit. On top of that he want a new shower light and a seperate pull cord switch to turn the fan on and off and a new shower 7.2KW. All this off an exisitng 1984 Ceramic Crabtree MCB board with no RCD.
What I can not decide as to what to do is put an 80A 30ma rcd before the whole board or pull the lighting circuit and shower circuit off the board and run it through a seperate RCD.
Can I get a 80A 30ma RCD main Breaker big enough for tails? I am struggling to find one.
The best option seems to be an RCD in front of the main board, there are already three sets of tails in a tight space for storage heating.
Any help would be welcome.

 

[Mac]

If they want all that work done,why not a new CU

 

[walec]

They do not want the cost, I wish they would make the job a lot easier.

 

[Spudnik]

You cannot have a 30mA RCD protecting the whole installation.

 

[walec]

Hello Jason, can you explain that a little further please, is that because the RCD is on the wrong side of the Isolator? or am I just not understanding.

 

[Deleted member 9648]

As Jason rightly says you cant have one RCD protecting the entire installation as there are regs now on a fault on one circuit affecting others. With one RCD a minor fault would shut down the whole lot.
Explain to the customer that a new 17th edition DB with at least 2 RCD's will be the best option for the new work to comply.Split the circuits to minimise disruption should one rcd trip...ie upstairs lights on one rcd....downstairs on the other etc. Alternatively put each circuit on an RCBO.

 

[Mac]

As Jason rightly says you cant have one RCD protecting the entire installation as there are regs now on a fault on one circuit affecting others. With one RCD a minor fault would shut down the whole lot.
Explain to the customer that a new 17th edition DB with at least 2 RCD's will be the best option for the new work to comply.Split the circuits to minimise disruption should one rcd trip...ie upstairs lights on one rcd....downstairs on the other etc. Alternatively put each circuit on an RCBO.

What about customers who wont pay for 17th edition CU.Main RCD switch is the only option

 

[walec]

As it happens I spoke with the customer today and he reluctantly agreed to a new board, but that in itself is a new challenge, the exisitng board is in a metal enclosure surrounded by storage heating controls. I will take a picture on friday, will be interested in your comments.
My main interest in the RCD before the CU is that of an earlier post. I have been asked to do some work elsewhere, outside lights, socket, down lights and when I turn up to have a look there is this 80A 30ma RCD in front of a wylex 100A main switch MCB CU. installed last month. Straight away I am thinking that can`t be right but can not find anywhere in the regs that tells me otherwise. So then I start think could I? Though I have to say it does not sit well. Thats why I told my other customer new board or nothing this morning. Can anyone point me to the page in the red book please?