Kilowatts Hour to Amps???

leo1 · 4 Mar 2006

"At the consumer unit, the cooker will require its own fuse way. A 30amp fuseway can support an appliance of up to 7.2kw providing that the control unit does not also have a socket outlet."

This appears to be our case, in which we aim to install an electric cooker in a circuit with a 30A MCB/fuse. Now, the irritating thing is, few online retailers will specify the overall power consumption of the appliances, while others will show the energy consumption in KW/h.

Say, what's the required fuse for a cooker with an energy consuption of 0.79, or 1.19 KW/h? Any handy formulas?

Thanks.

Adam_151 · 4 Mar 2006

KWH doesn't tell you how much power an appliance takes at one time if I had a 7kw shower, and I used it for an hour, it would have used 7kwh hours (7 units), if I had a 1kw hair dryier and left it one for 7 hours, it too would have consumed 7kw, but they are totally different sized loads

The point I'm making is that kwh has time factored into it, and its used for telling how much you have used to take money off you, it means nothing in terms of designing circuits

kwh = kw * time (in hours)

swelec · 4 Mar 2006

I will ignore the fact that you got confused over kW and kWh

Power (watts ) = volts X amps

amps = Power / volts

Assuming UK supply is 230 volts

0.79 kW or 790 Watts / 230 volts = 3.44 amps

leo1 · 4 Mar 2006

Thank you for both replies above.

swelec said:
I will ignore the fact that you got confused over kW and kWh

Power (watts ) = volts X amps

amps = Power / volts

Assuming UK supply is 230 volts

0.79 kW or 790 Watts / 230 volts = 3.44 amps

I would like to mention it is not my confusion and am aware of the above.

That is the way catalogues (such as Argos) will give any indication of power consuptions and, correct me if I'm wrong, 3.44 amps sounds way below what a 4 hob ceramic cooker, oven and grill would take. Doesn't it?

Trying to find a suitable electric cooker online is proving quite a frustrating experience, given that hardly anyone will quote such an essential specification as this. We have a 30A fused circuit and aim to buy a cooker within that spec.

Or, you have sites like John Lewis saying things like "Power rating: 45 amps". Amps is not a power unit!!!! The only mention (for the same appliance!) in the manufactorers site is "30A fuse required" which sounds plain and dumb enough, but as the same legend repeats for all cookers (including the high consumption ceramic double ovens) I got to wonder. I have enquired about this and I look forward to a satisfactory reply.

Thanks again.

swelec · 4 Mar 2006

leo1 said:
Say, what's the required fuse for a cooker with an energy consuption of 0.79, or 1.19 KW/h? Any handy formulas?

Thanks.

Your figures not mine

leo1 · 4 Mar 2006

Argos specification, said above.

JohnD · 4 Mar 2006

True (but wrong)

CONVENTIONAL OVEN TECH SPECS:

Energy efficiency rating 'A'.

Energy consumption 0.85kWh and 0.77kWh forced air.

Net cavity volume 47 litres.

http://www.argos.co.uk/static/Product/partNumber/4906818.htm

HandyJon · 4 Mar 2006

Having a quick gander at one of the Argos cookers I see a .79kWh specification. But it's for the oven, not the hob.

For example http://www.argos.co.uk/static/Produ...5948.Cookers>C$cip=35953.Electric+cookers.htm (Zanussi ZCE7551 Stainless Steel Electric Cooker) says top oven is .79kWh and bottom is .98kWh, but it doesn't say anything about the hob rating. Ovens can be run off 13A plugs so the two ovens will take about 7.7A if on together. That is if Argos are trying to say kW and not kWh.

Steve · 4 Mar 2006

Thats the energy efficiency rating figure - the amount it uses each hour. Not the rating of the actual elements! I have concluded this is a bad idea as it may lead DIYers to start putting these cookers on 13A plug tops, uner the impression the whole thing will only ever consume <1kw (them not knowing any typical figures for cookers etc)

swelec · 4 Mar 2006

just read up on energy efficiency ratings

they are quoted in kWh

imagine an oven rate at 5 kW

It will take 5000 watts / 230 volts = 21.74 amps

if you assume the heater cycles on for one minute reaches temperature then swiches off for four minutes then in one hour it will consume

(12 minutes / 60 minutes) x 5 kW or 1kWh

I can see the confusion now

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Kilowatts Hour to Amps???

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