yet another cooker question

[ixdes]

Seems to be the time for new kitchens!

Anyway, in the ever continuing saga of trying to get an electrician to come and look at running a new cooker circuit to feed a microwave/combi oven, one person we have spoken to suggested this:

instead of ripping half the house apart to run a new cable, providing the current cable is large enough simply up the mcb in the main CU to 45A from the current 30A. Then install a new mini CU in the kitchen fitted with 20A & 16A MCB's as required by the new cookers, then run cables to new switches for each cooker.

I can see what they were getting at (I guess he didn't want the hasstle of running new cables everywhere), but it sounds a little strange to me. Would that really be acceptable?

 

[nstreet]

What else is running on the circuit you are intending to up rate? What size cable has been used?

 

[ixdes]

there is nothing else on the circuit. It is an existing radial supplying a cooker point with 13A socket. Have not checked the cable dia yet, but the MCB in the CU is only 30A. This was installed long before we bought the house, by the local council I think when they upgraded the houses.

We would be doing away with the 13A socket anyway.

 

[Adam_151]

What size is the existing cable? how long is it? what route does it take? (is it bundled? travels through insulation?)


and what is the rating of the cookers?, 16A + 20A = 36A, now the 16A and 20A values are likely to be rounded up to the next nearest breaker size (you can't get a 13.5A breaker for example)

if you had for examplea 3kw load on the 16A breaker that would be 13A, and a 3.8KW load on the 20A one, that would be 16.9A, that gives a total load of just under 30A, clearly these are fiqures I've just plucked out the air to demo the point I'm making, chances are though, as its a submain, you will be able to allow some deversity here (but thats opening a can of worms (as its just cooking appliences on the submain, and diversity and cooking appliences usually results in interesting debates on this forum) )

 

[ixdes]

I have managed to get the rating info on the cookers. The combi is rated max 3.3KW, the oven at max 3.5KW, with the general operatin of both being a bit less. By my wreckoning that comes to around 28A.

So, as the current circuit is protected by a 30A breaker, do we still need to install a mini CU in the kitchen, or could we just have a second switch and outlet looped off the existing switch?

Cheers.

 

[mapj1]

It would be OK either way, as far as regs are concerned, so long as the cables can cary the full current the breaker might supply. The idea of separate isolation might be desirable if there is ever a fault.