Installing a hob but no oven

[Bert Coules]

I've searched around but can't find a clear answer to this; apologies if the subject is covered somewhere.

In my new kitchen I'm thinking of having a built-in hob but no oven. The hob will be a small two-ring model, probably ceramic: the specs of a typical example (by Siemens) are given as Total load 2.9, Maximum current draw 12kw.

Does a hob like that require its own dedicated circuit? I assume it can't (or shouldn't) simply be connected into a general ring circuit. Does the hob have to be connected via a "proper" cooker point, or will a fused isolating switch leading to a cooker connecting plate be acceptable?

Many thanks,

Bert

[burbeck]

the specs you gave dont add up ? read them again.

2.9 what ? apples oranges 12kW sounds wrong to, is that supposed to be 1 . 2 kW ? regards bob

[Owain]

Are you *sure* you've got that right?

Total load 2.9 kW, Max current draw 12 A would be more reasonable.

A 12 kW load would require > 50A circuit. Such a hob would be very unlikely to be found in a domestic kitchen, especially a small one.

It should really have its own circuit, and you might as well install a

30A cooker circuit to allow for a future upgrade to a 4-ring hob at a later date.

It requires a double pole isolator within 2m of the hob. A FCU would be acceptable, but I think it would be better to use a 20A switch on a

16/20A MCB, or a 30A cooker switch on a 30A MCB. You can get 30A switches the same size as a double socket.

The cooker instructions might state a 16A circuit is required - that's common amongst European appliances. I'd suggest using a 16A MCB in that case, but using heavier cable to allow upgrade to a 30A circuit nonetheless.

Owain

[Dave Plowman (News)]

The limit for connection to a ring is 13 amps. So multiply volts by amps for watts. 13 x 230 gives 2990 - let's say 3 Kw.

12Kw will draw - watts divided by volts - so 12,0000 ------- = 52 amps 230

That would suggest using 10mm cable.

[Bert Coules]

Thanks to everyone for the replies.

Here are the specs, taken directly from the Siemens brochure:

Zone rating (kW): Front: 1.2 Back 0.7 - 1.2 Total connected load: 2.9 (obviously kW, though it doesn't actually say so) Maximum current draw (kW): 12

On re-reading it, I think there's a misprint in the brochure: it seems pretty obvious that the "kW" designation should appear at the head of the column for total load, not in the one for maximum current draw.

That makes the two-ring hob, as Owain suggested:

With that rather less scary rating, could the hob be connected into an existing 30A ring circuit, as long as it was via a properly rated isolating switch unit?

Thanks again,

Bert

[Bert Coules]

Owain,

As you might have seen from my earlier reply, I suspected that there was a misprint in the Siemens brochure. I think this is now pretty much confirmed: I just noticed that in the next column the weight of the hob is given as 5 Amps!

Bert

[Owain]

If the hob is connected to a 30A ring circuit, it *must* be connected by a *Fused* Connection Unit with a 13A fuse.

However the loading on the ring circuit must be considered -- if the ring is already heavily loaded (kitchen rings usually are, with washing machine, tumble, dishwasher, kettle etc), it would be wiser to install a dedicated circuit.

Owain

[Bert Coules]

Owain,

washing

install a

Clearly, that's good advice. Thanks very much.

Bert

[Dave Plowman (News)]

IIRC, any appliance designed to be plugged into a normal 13 amp socket comes with a fitted lead and plug.

But I'd say a two ring hob will be ok to be plugged in.

2.9 kW equates to 12.6 amps at 230 volts, or 12 amps at 240 volts.

[Bert Coules]

Dave,

It seems that way to me. I do take Owain's point about the total loading of the complete circuit, but I can't see many instances arising when I'd have both rings going full blast while simultaneously using a load of other relatively high-rated appliances (which I don't have room for anyway - which is why I'm installing only a two-ring hob...)

Oh, blow.

Bert