Switches near hobs

[DavidA1982]

Is the builder issuing you with electrical certificates for the work being carried out? It is very possible that the bathroom electrics may require notification to building controls and any new circuits in the kitchen will. There will also be requirements for RCD protection to be complied with.

Thanks - yes, he is, which is why I'm saying that he must be using an electrician. At least, the quote says that all works will be carried out by a qualified electrician. I've put in the building notification on the basis that this is the case and the builder knows that.

Not even sure what the model number for the oven is - I don't have it here (and I bought it second-hand). But it is the exact same model as the last one, and the electrician in the last house put in 6mm cable on a 32A circuit, as you say, and that is what the electrician has done in this house too. I'll try to find a model number and let you know - I appreciate the help.

If I could use the cooker circuit for the hob too, that would be fantastic. I could probably use the crappy 1mm circuit that the electrician left me to power the plinth heater; and the 6mm circuit to power the hob and cooker. That would work really well.

 

[DavidA1982]

The oven says 4.4kw on the side - does that help?

Also - does this mean that my "energy saving" induction hob draws more power than my big old double oven?! Surely not?!?

 

[EFLImpudence]

What's a larder unit?

If larder is being used in the conventional sense then having an oven/hob next to and heater under it is not a good idea.

 

[JohnW2]

The oven says 4.4kw on the side - does that help?

Indeed. That plus your 6.8kW induction hob would easily be both supplied by the 6mm² 32A cooker circuit you have.

Also - does this mean that my "energy saving" induction hob draws more power than my big old double oven?! Surely not?!?

Almost any hob will have a greater total power requirement than an oven - but don't forget that there are 4 (or whatever) hotplates which you will rarely use all at once - and, in any event, they cycle on and off by thermostatic control, and are therefore not drawing power for all the time you are cooking on them. "Energy saving" is likely to derive from greater efficiency, so that the 'hotplate' will be drawing power for less of the time than with a less efficient hob.

Kind Regards, John

 

[JohnW2]

What's a larder unit? ... If larder is being used in the conventional sense then having an oven/hob next to and heater under it is not a good idea.

Intended as a food storage cupboard - but I've seen all sorts of things in them! Provided one is sensibly selective about what foodstuffs are (and are not) stored in it, I don't think that being next to a hob would be an issue. Being next to an oven might be a bit more of a concern.

Kind Regards, John

 

[PrenticeBoyofDerry]

The oven says 4.4kw on the side - does that help?

That would give a maximum output of 11.2kw, a diversity calculation can be factored in, which would mean if an isolator without socket-outlet was fitted then the you are looking less than 22A current which a 6.00mm T&E cable will safely carry providing there are no de-rating factors to consider such as cable routes within containments such as trunking/conduit and the cable is not within thermal insulation along parts of it's route.

Also - does this mean that my "energy saving" induction hob draws more power than my big old double oven?! Surely not?!?

Generally have an output that is greater than the oven, but the load demand will cycle during heating of the pans and will be always be lower than the maximum rating.

 

[JohnW2]

... you are looking less than 22A current which a 6.00mm T&E cable will safely carry providing there are no de-rating factors to consider such as cable routes within containments such as trunking/conduit and the cable is not within thermal insulation along parts of it's route.

Unless a 25A MCB could be found for the OP's CU, the cable obviously needs to be able to safely carry 32A (not just 22A), but I would be very surprised if the installation method resulted in de-rating of its current capacity to anything like that low - so that cable (with a 32A MCB) will almost certainly be fine. The OP's electrician will hopefully be able to confirm that easily (maybe with some guessing about what goes on within walls!).

Kind Regards, John

 

[winston1]

I could probably use the crappy 1mm circuit that the electrician left me to power the plinth heater;

No you can't. 1mm is only for lighting circuits.

 

[PrenticeBoyofDerry]

Unless a 25A MCB could be found for the OP's CU, the cable obviously needs to be able to safely carry 32A (not just 22A), but I would be very surprised if the installation method resulted in de-rating of its current capacity to anything like that low - so that cable (with a 32A MCB) will almost certainly be fine. The OP's electrician will hopefully be able to confirm that easily (maybe with some guessing about what goes on within walls!).

John I had already pointed this out in an earlier post, 6mm and 32A circuit.
I was calculation diversity for the OP, not that a 22A breaker should be sourced to use, I think you know that?

Why do you make posts like this? You are fully aware of what I was suggesting.

 

[JohnW2]

I could probably use the crappy 1mm circuit that the electrician left me to power the plinth heater...

As winston has said, if it is 1mm², then that would not be allowed, since 1.5mm² is the smallest allowed for non-lighting circuits. However, if it;s actually 1.5mm² that should be OK for your plinth heater. As a matter of interest, does that supply have an MCB of its own in your CU and, if so, what size/rating is it?

Kind Regards, John

 

[DavidA1982]

Thanks all, this is really, really helpful. What I'm taking from this is that I can install the kitchen on the basis that the electrician can supply the oven and hob from the existing cooker circuit (the rating for it, per the installation certificate, is 40).

The oven is just the other side of the thin wall I've been talking about - no more than a metre from the consumer unit. I would hope that the electrician can simply run the cable to the hob along the floor under the units - anything else will create a bit of a mess now.

And I won't use the existing "induction hob" circuit for anything.

 

[JohnW2]

John I had already pointed this out in an earlier post, 6mm and 32A circuit.

We both said that 6mm² on a 32A MCB would almost certainly be OK for the total cooking load indicated by the OP (in fact, I wrote that before you did).

I was calculation diversity for the OP, not that a 22A breaker should be sourced to use, I think you know that? Why do you make posts like this? You are fully aware of what I was suggesting.

Yes, I am fully aware of what you meant, but I was concerned that the OP might not have been - which is why I clarified it for his sake. Although I know it's not what you intended, your words seemed to be implying that the cable only had to be able to so 'safely carry' 22A.

Kind Regards, John

 

[DavidA1982]

I could probably use the crappy 1mm circuit that the electrician left me to power the plinth heater...

As winston has said, if it is 1mm², then that would not be allowed, since 1.5mm² is the smallest allowed for non-lighting circuits. However, if it;s actually 1.5mm² that should be OK for your plinth heater. As a matter of interest, does that supply have an MCB of its own in your CU and, if so, what size/rating is it?

Kind Regards, John

Thanks. Yes, it does. I think it's 6A - it's a wylex MCB, and it says:

B6
NHXB06

Rather amazingly, I have four circuits in my kitchen (ignoring the downstairs lighting circuit). The ratings, and the cable sizes (taken from the installation certificate) are:

- 40A cooker (6mm)
- 32A kitchen ring (2.5mm)
- 6A circuit for a single pull-cord switch in the larder (this was supposed to be the "induction hob" circuit.) (1mm)
- 6A circuit for a tiny little extractor fan (1mm)

I can understand the dedicated circuit for the larder light (I asked for this, so I could put in an induction hob). I cannot for the life of me work out why there is a dedicated circuit for the extractor fan, but never mind.

It's a bit of a pain that I cannot use either of my seemingly useless 1mm circuits for the plinth heater, but if that's the case, that is the case. I'll just have to extend the kitchen ring to accommodate it.

 

[DavidA1982]

Unless a 25A MCB could be found for the OP's CU, the cable obviously needs to be able to safely carry 32A (not just 22A), but I would be very surprised if the installation method resulted in de-rating of its current capacity to anything like that low - so that cable (with a 32A MCB) will almost certainly be fine. The OP's electrician will hopefully be able to confirm that easily (maybe with some guessing about what goes on within walls!).

John I had already pointed this out in an earlier post, 6mm and 32A circuit.
I was calculation diversity for the OP, not that a 22A breaker should be sourced to use, I think you know that?

Why do you make posts like this? You are fully aware of what I was suggesting.

For what it's worth, I appreciate repeated comments actually - safety in numbers and all that! Thanks to everyone who has contributed here, it's given me a plan of action for tomorrow, as well as a shopping list of things to ask the electrician to do.

 

[PrenticeBoyofDerry]

What plinth heater do you have model and output, is this purely electrical or if you have not yet purchased one, is it possible to have one connected to the central heating, then you will only need electrics to power the fan.