cooker circuit - confirmation OK please

[crazy_jon]

Hi

I have recently bought a new house and the cooker circuit is run with 6mm cable. The cooker is a rated at 2.1kw for the oven and 1.8kw for the grill. The cooker circuit also spurs to a socket for the gas hob ignition. I'm told that nowadays 10mm cable is used for cooker circuits.
Can someone please confirm to me that the 6mm cable is OK? And if I replace the oven with a more powerful one, what Kw can I go up to?

 

[Chri5]

Jon

Cable distance and how the cable is contained / run is a factor in rating a cable load.

10m 6mm run clipped to walls = 8.7kw max

10m 6mm run contained in walls with insulation = 7.5kw max

If you post the distance, the cabling route installation method (trunking, buried in walls, loose lay under floor) I can offer a more accurate assessment.

Whats the fuse rating at the board for the cooker circuit ? Obviously this plays a large part in the scheme of design.

 

[crazy_jon]

Hi Chris

the fuse at the board is a 32Amp MCB, the cable is run under the upstairs floor and the distance to the kitchen is approx 7m give or take a bit more for going up under the floor and then down again into the kitchen I suppose

Thanks

Jon

 

[Space cat]

What size fuse or breaker do you have and what do you mean by "spurs to a socket"? You can have a socket built into the cooker switch but there shouldn't be a separate socket on the same circuit.

Your present oven and grill will take a total current of about 16 amps which is well within the capacity of 6 sq mm cable (30 amps or more depending upon how it's run). You don't mention hob rings. Is this an oven and grill only?

Edit: I see Chri5 beat me to it.

 

[Chri5]

32 amp x 230v = max load, less the load of peripheral items such as the cooker hood (about 300w I think).

A 40 amp fuse (next up) will not support a 6mm cable,

 

[crazy_jon]

the hob is gas and it has a plug on it for the ignition, so its just the oven/grill thats electric.

Thanks for the responses

 

[Space cat]

The cooker circuit also spurs to a socket for the gas hob ignition.

 

[mdbalson]

The cooker circuit also spurs to a socket for the gas hob ignition.

He means that a socket has been spured off of cooker circuit, to plug in the feed to the electric ignition on the gas hob.

 

[Space cat]

He means that a socket has been spured off of cooker circuit, to plug in the feed to the electric ignition on the gas hob.

That's what I was afraid of. You really shouldn't do that.

 

[TrueBlue]

No thats definately not PC.

 

[Steve]

He means that a socket has been spured off of cooker circuit, to plug in the feed to the electric ignition on the gas hob.

That's what I was afraid of. You really shouldn't do that.

So you cant even spur off an electric hob circuit to feed an electric 3kw oven? (As I have advised several times to people on this forum)

As it stands, we have a 7kw electric hob, and a gas oven. The gas oven is plugged into a single socket, which is supplied from the cooker switch by 6mm² cable and protected at source by a 32 amp MCB. I dont see anything wrong with it, since its all protected and isolatable.

 

[securespark]

It is acceptable (in my mind not good practice but acceptable) to wire a socket off a cooker supply providing two conditions are met:

a: the socket is wired in the same size cable as the rest of the circuit and it has a CCC > or equal to that of the CPD.

b: the CPD can take the increased load.

PS. You can apply diversity to a cooker circuit.

Eg 14,600W cooker.

Convert to amps - 63.48A

Take off 10A - 53.48

Take 30% of 53.48 = 16.04A

Add on the 10A = 26.04

Add 5A if you have a socket outlet on the same plate as the cooker switch:

31.04A

As Steve says, the circuit is fed in a cable size that equals or exceeds that of the CPD and as long as you can site both appliances within 2m of the isolator, you only need one for both.

 

[Pensdown]

Because more and more cookers/hobs are being supplied with a fitted 13amp plug I too can't really see a problem with a socket fed from the CCU.

I think I would add a C to the SS post,

c: The socket has an integral 30mA RCD.

That solves 3 problems.

1. If it's TT must have one.
2. If TNC-S it takes away the confusion with use for outside equipment.
3. It gets over the design problem of reducing the cct disconnection time and leaves the cooker and hob non RCD.

 

[securespark]

Fair enough, I s'pose Pens, but cooker control units don't have RCD-protected sockets...

 

[Pensdown]

Aren't we talking about wiring a separate socket from the CCU?