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Electric Hob Instructions.
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1762 Posts
Question
I have been asked to estimate for a small rewire. The rewire includes a new supply to an electric hob. I asked the property owner the rating of the hob so that I can size the cable. He said that it can be run off a 13 Amp plug, so says his mate who is an electrician.

I asked to see the makers' instruction for the hob. It stated that the hob should be supplied from a switched fused connection unit. So far so good I thought.

But then the requirement was for a 32 Amp. fuse to be inserted into the switched fused connection unit. So much for following manufacturers' instructions.

Z.
3 Replies
AJJewsbury
1766 Posts
Is it induction?

I know that some models of induction hobs can be programmatically throttled to one of a number of supply ratings - 13A sometimes being one of them. Without being so programmed, you'd need full sized supply (and have somewhat better cooking performance). So it's possible that the instructions are getting confused trying to specify two different requirements at the same time.

Or it could be that the original requirement for a means of connection to be made in a way that provided both overcurrent protection and isolation mutated in translation and ended up by accident happening to resemble a well known phrase in the UK that describes a particular 13A accessory.

  - Andy.

The "cheaper" induction hobs come with a 13A plug and are limited in firmware to 3KW total power and you cannot change this limitation.
This means that if you use just one "ring" then you can use the full 3KW on it to boil a pan of water. However if you turn that ring down to say 1KW to simmer it, and now want to boil another pan of water on another ring then the second pan will be limited to 2KW. Many people fail to realise this limitation at the cheaper end of the induction hob market - that you cannot use all the 4 rings full or even half blast at the same time - just the one.

The expensive and higher power ones have a user settable management facility within them. 
Unlimited (factory setting) is to use the full rating of the hob. so if the hob is rated at say typically 7KW then you can indeed boil two pans at 3KW each at the same time.
However the user can if they wish reduce the max power of the hob if it it to be used on a reduced capability power source.  Typically I've seen the other settings to be 13Amps, 16A, and something like 22 or 25 amps.

I'not sure about the cheaper ones but the higher power ones have a cooling fan underneath and specific ventilation requirements in the installation manual/leaflet.

I've said above 3KW as a nominal ring rating - usually its around 2.5KW normal max. some have a slightly higher setting of 3 point something KW available as a boost on one only at a time.
 
Chris Pearson
1664 Posts

Helena Handcart:

The "cheaper" induction hobs come with a 13A plug and are limited in firmware to 3KW total power and you cannot change this limitation.
This means that if you use just one "ring" then you can use the full 3KW on it to boil a pan of water. However if you turn that ring down to say 1KW to simmer it, and now want to boil another pan of water on another ring then the second pan will be limited to 2KW. Many people fail to realise this limitation at the cheaper end of the induction hob market - that you cannot use all the 4 rings full or even half blast at the same time - just the one.

This limitation is not limited to cheaper devices. I don't think that customers "fail to realise this limitation" - they simply don't understand the physics. Who would cook Christmas dinner in an oven which with its companion cool oven is limited to 3 kW?

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