Constraints on use of a 3.7kW induction hob?

itm2

We are planning a new kitchen, and have earmarked a Bosch PWP631BF1B electric induction hob to replace our gas hob. One of the reasons for choosing this model was that it could be connected to a 13A power supply (it's rated at 3.7kW). We only have a single 32A power supply in the kitchen and the oven we are planning to purchase has a power rating of 3.35kW/16A, so we figured that we couldn't have a 7kW hob and a 3.35kW oven connected to the same 32A supply?
My question is: to what extent will the relatively low power rating of the hob affect our usage? For example, if we always pre-boil water in the kettle would we be able to have 2 rings cooking vegetables as well as a third frying meat at the same time?
 

neilmcl

The power output for the cooking zones will never go above 3 KW so you'll struggle with having multiple zones operating at any decent output, and you'd probably soon get fed up of having to pre-boil your water from the kettle as you suggest as well as pretty much negating the convenience of the induction hob in the first place if that's what you're going to have to do. I don't personally have experience of these plug-in models, I have a full powered, direct wired version, but if I was going to be compromised so I'd probably look at an alternative.

FreeBear

neilmcl said: The power output for the cooking zones will never go above 3 KW so you'll struggle with having multiple zones operating at any decent output,

Agreed. Whilst most of the time I'm only using two rings on my induction hob, there are times when all four are on the go (Xmas for example). It would be a major pain in the a... if it were limited to just two rings.

I would urge you to have a dedicated supply put in along with a suitably rated isolation switch. Should you ever decide on a bigger oven and/or hob, you'll be thankful for it. You'll also have the choice of a wider range of hobs rather than being limited to ~3Kw models.

Homer_home

itm2 said:

We are planning a new kitchen, and have earmarked a Bosch PWP631BF1B electric induction hob to replace our gas hob. One of the reasons for choosing this model was that it could be connected to a 13A power supply (it's rated at 3.7kW). We only have a single 32A power supply in the kitchen and the oven we are planning to purchase has a power rating of 3.35kW/16A, so we figured that we couldn't have a 7kW hob and a 3.35kW oven connected to the same 32A supply?
My question is: to what extent will the relatively low power rating of the hob affect our usage? For example, if we always pre-boil water in the kettle would we be able to have 2 rings cooking vegetables as well as a third frying meat at the same time?
 

A 3.7kw hob cannot be connected to a 13a plug as it will potentially draw just over 15a

Where did you get a 7kw hob from when you said at the start of your post it's 3.7kw?

Regardless you can't connect the oven and hob to your kitchen supply , it needs to go on its own supply because if you turn the oven on and the hob and then stick the kettle on  you will overload your kitchen supply 

As putting in a new circuit is notifiable work you will need to engage the services of an electrician 

itm2

Homer_home said:

itm2 said:

We are planning a new kitchen, and have earmarked a Bosch PWP631BF1B electric induction hob to replace our gas hob. One of the reasons for choosing this model was that it could be connected to a 13A power supply (it's rated at 3.7kW). We only have a single 32A power supply in the kitchen and the oven we are planning to purchase has a power rating of 3.35kW/16A, so we figured that we couldn't have a 7kW hob and a 3.35kW oven connected to the same 32A supply?
My question is: to what extent will the relatively low power rating of the hob affect our usage? For example, if we always pre-boil water in the kettle would we be able to have 2 rings cooking vegetables as well as a third frying meat at the same time?
 

A 3.7kw hob cannot be connected to a 13a plug as it will potentially draw just over 15a

Where did you get a 7kw hob from when you said at the start of your post it's 3.7kw?

Regardless you can't connect the oven and hob to your kitchen supply , it needs to go on its own supply because if you turn the oven on and the hob and then stick the kettle on  you will overload your kitchen supply 

As putting in a new circuit is notifiable work you will need to engage the services of an electrician 

This is the hob - it comes with a 13A plug:
https://www.johnlewis.com/bosch-serie-4-pwp631bf1b-induction-hob-black/p3196203?s_ppc=1dxDSA-ELECTRICALS-PP39700045680842887&tmad=c&tmcampid=1&gclid=CjwKCAjw4rf6BRAvEiwAn2Q76jPcn_AUXcURgwl_jaFeepXmO2ps6K7UVYOxPIJYeqLH3WxBiksi4xoC1YEQAvD_BwE&gclsrc=aw.ds

neilmcl

itm2 said:

Homer_home said:

itm2 said:

We are planning a new kitchen, and have earmarked a Bosch PWP631BF1B electric induction hob to replace our gas hob. One of the reasons for choosing this model was that it could be connected to a 13A power supply (it's rated at 3.7kW). We only have a single 32A power supply in the kitchen and the oven we are planning to purchase has a power rating of 3.35kW/16A, so we figured that we couldn't have a 7kW hob and a 3.35kW oven connected to the same 32A supply?
My question is: to what extent will the relatively low power rating of the hob affect our usage? For example, if we always pre-boil water in the kettle would we be able to have 2 rings cooking vegetables as well as a third frying meat at the same time?
 

A 3.7kw hob cannot be connected to a 13a plug as it will potentially draw just over 15a

Where did you get a 7kw hob from when you said at the start of your post it's 3.7kw?

Regardless you can't connect the oven and hob to your kitchen supply , it needs to go on its own supply because if you turn the oven on and the hob and then stick the kettle on  you will overload your kitchen supply 

As putting in a new circuit is notifiable work you will need to engage the services of an electrician 

This is the hob - it comes with a 13A plug:
https://www.johnlewis.com/bosch-serie-4-pwp631bf1b-induction-hob-black/p3196203?s_ppc=1dxDSA-ELECTRICALS-PP39700045680842887&tmad=c&tmcampid=1&gclid=CjwKCAjw4rf6BRAvEiwAn2Q76jPcn_AUXcURgwl_jaFeepXmO2ps6K7UVYOxPIJYeqLH3WxBiksi4xoC1YEQAvD_BwE&gclsrc=aw.ds

And as mentioned the maximum output is only 3 KW, hence why it can have a 13A plug and why it will be severely compromised if you wanted to use multiple cooking zones at the same time.

itm2

It does seem that a 7kW hob would be a much better idea. Unfortunately we live in a townhouse (consumer unit on the ground floor, kitchen on the 1st floor), so having another high-current supply installed in the kitchen will probably cost more than the hob :0(

Ectophile

Can I just point out that before the modern trend for fitted cookers, people used to buy freestanding cookers.  They would have an oven, grill and four rings, all on a 32A breaker (or 30A fuse).  The breakers never tripped.

But install the rings and oven as separate appliances, and people think they can't possibly go on the same circuit, because they will overload it.

The magic word is "diversity".  That doesn't mean all your kitchen appliances have to be different colours.  It's that nobody turns everything on full at the same time.  Even if you did turn everything on for a short time, a 32A breaker won't even trip at 36A, and the wiring in your house won't catch fire if moderately overloaded for a few minutes.

itm2

Ectophile said:

Can I just point out that before the modern trend for fitted cookers, people used to buy freestanding cookers.  They would have an oven, grill and four rings, all on a 32A breaker (or 30A fuse).  The breakers never tripped.

But install the rings and oven as separate appliances, and people think they can't possibly go on the same circuit, because they will overload it.

The magic word is "diversity".  That doesn't mean all your kitchen appliances have to be different colours.  It's that nobody turns everything on full at the same time.  Even if you did turn everything on for a short time, a 32A breaker won't even trip at 36A, and the wiring in your house won't catch fire if moderately overloaded for a few minutes.

I did think about that myself. I think if you have that conversation with a group of qualified electricians you'd probably start a mini civil war - I suspect there isn't consensus on what is actually safe/sensible (or even legal?).

onomatopoeia99

Mickey666 said:

Diversity is an important factor when designing kitchen circuits and is best left to a qualified electrician to work out what’s really required in practice.

It's a really simple calculation that anyone that passed their maths GCSE could do (and probably anyone that failed it could do as well, to be honest).

The only magic is the cost of buying a copy of BS 7671 where the calculation is printed.

Risteard

I have a 7kW+ induction hob and an oven on a standard 32A cooker circuit. It's not an issue. Diversity allows 15kW of cooking equipment on a standard 30/32A cooker circuit. I have never limited what I use at a time with it. Electrical competence means I understand that I don't have to.