induction hob wiring

[psmk2]

j have a hotpoint double oven at 4.8kw and a whirlpool induction hob at 7.2kw....can these be wired together in a junction box on 6mm wire with a 30 amp cu fuse......the oven also has an isolater switch fitted

 

[EFLImpudence]

Yes.

Use a dual outlet cooker connector.
http://www.alertelectrical.com/prod/1022/click-45a-dual-cooker-outlet-plate-prw217

 

[psmk2]

Thanks ill get one ordered tomorrow.......

 

[eveares]

Yes.

Are you serious , that's 12kw or 50-52Amps in total!

6mm T&E supports 47 amps at a maximum, not accounting for voltage drop or de-rating factors.

I would put the hob (31.3 Amps) and oven (20.8 Amps) on their own MCB if possible (Each wired in 4mm or 6mm with a 32A MCB/Fuse), if not you will need a 50Amp MCB/Fuse and 10mm cable.

 

[EFLImpudence]

Yes.

Are you serious

Yes, and totally correct.

, that's 12kw or 50-52Amps in total!

What about diversity?
https://www.tlc-direct.co.uk/Book/6.5.2.htm

6mm T&E supports 47 amps at a maximum, not accounting for voltage drop or de-rating factors.

That is true.

I would put the hob and oven on their own MCB if possible (Each wired in 4mm or 6mm with a 30A MCB/Fuse), if not you will need a 50Amp MCB/Fuse and 10mm cable.

Then you will be causing your customers unnecessary expense for unnecessary work.

99% of cookers in the country are on 30/32A and 6mm².

 

[eveares]

Diversity between a electric oven and a induction hob would hopefully not be applied to much or excessively due the likely demand that they could easily operate together at a total power over 7.36Kw.

I have my 7.2Kw induction hob on a 6mm/32A MCB and my single oven on a 4mm/16A MCB.

You could easily run into a situation where you will have the hob on full (i.e. rapid boil/all induction zones on) and the main oven say drawing 2.5Kw, 9.7Kw/42 Amps in total does not seem unreasonable.

 

[Taylortwocities]

As EFLI says, it will be fine. Especially with a BS3036 fuse in situ.

 

[ban-all-sheds]

eveares - what is your position on applying diversity to a typical 110cm all-electric range cooker with an induction hob?

 

[ericmark]

In the main any induction heat area with start to cycle within 4 minutes under normal cooking an induction uses less power than any other electric hob only when used commercially swapping pans continually could it possibly use more than any other electric hob.

OK with some you can select boost and you may be able to use two rings at in my case 6.8kW but the electronics limits the time to around 5 minutes and for cables to over heat or for a MCB to over heat takes time and it will just not run for long enough.

Even with pan swaps every time the pan is removed it switches off automatically. What you have to remember most hobs have 4 heat areas and once food is boiling the energy required to maintain the food at boiling is the same for any hob what changes is the energy which escapes. And with induction far less power energy escapes so what ever the info plate says does not really matter it uses less energy than any other hob so clearly does not need as large of a supply as any other hob.

 

[eveares]

As EFLI says, it will be fine. Especially with a BS3036 fuse in situ.

Ok, fair enough. Was not saying it would not be safe anyway, just possibly not practical. Never mind anyway, was only my opinion.

Are you also using the first 10A add 30% of remaining total current as the diversity?

eveares - what is your position on applying diversity to a typical 110cm all-electric range cooker with an induction hob?

I would have based it on around 75-80% of the total power.

 

[ban-all-sheds]

I would have based it on around 75-80% of the total power.

Why?

Do you use the same % with a traditional single oven, 4-ring hob, 60cm cooker?

 

[EFLImpudence]

Ok, fair enough. Was not saying it would not be safe anyway,

You gave that impression.

just possibly not practical.

Quite the opposite; it is your proposal which is not practical.
The OP has the necessary already installed; connected to which there would originally have been a cooker.

Never mind anyway, was only my opinion.

It's not a question of opinion.

Are you also using the first 10A add 30% of remaining total current as the diversity?

That's how it is done. It results in 22A (27A with socket)
26% (10%) spare capacity.

I would have based it on around 75-80% of the total power.

That would require 10mm² cable with a 40A 3036.
Have you ever come across such a circuit?

 

[roasty]

Diversity is a funny thing.
It still doesn't seem 'right' to me, but to each their own.

During the interim period where I was fitting our kitchen, but hadn't quite done it all 'properly'….ahem! We had the induction hob (6-7kw) two single ovens (one with microwave) kitchen sockets, washing machine, tumble dryer and dishwasher all hanging (literally) off one 6mm with a 32amp RCBO, I think it tripped once in about 3 months.

Since then, each oven is on it's own 16a radial, the hob on a 32a radial, washer and dryer have their own 20a radial and the kitchen sockets split over two more 20a ones. Easy way to use up ways on your CU and as I had already proved it's almost entirely unnecessary. But I did it anyway, it made me feel better…but totally unnecessary.

Moral of the story? Diversity might not seem right, but it tends to more than work in practice.

All the best
-Dan

 

[eveares]

Ok, fair enough. Was not saying it would not be safe anyway,

You gave that impression.

Well, I did not mean to - sorry.

It's not a question of opinion.

All I was trying to say, is I initially and incorrectly assumed you would get no or very little diversity for a cooker/hob combo.

That would require 10mm² cable with a 40A 3036.
Have you ever come across such a circuit?

Yes..... but not in a domestic property, but I have also not ever seen a separate electric hob over 3Kw and a oven on the same circuit either.

 

[JohnW2]

All I was trying to say, is I initially and incorrectly assumed you would get no or very little diversity for a cooker/hob combo.

As you've been asked, why do you see a difference between an oven+hob (separate units) and a cooker (oven+hob in same unit)?

Yes..... but not in a domestic property, but I have also not ever seen a separate electric hob over 3Kw and a oven on the same circuit either.

As above, what's all this obsession with 'separate'? You surely must have seen large cookers (with hob plus multiple ovens) 'all on one (probably 30/32A) circuit', haven't you? (one doesn't actually have a choice!)

Kind Regards, John