Oven and hob connection

[parkie83]

I have a 6kw hob and 3.2kw oven that I would like to connect to an existing 6mm cable (which is currently protected by a 40A MCB). The installation guides say to use 2.5mm cable for the hob and 1.5mm cable for the oven. How do I do this?

 

[holmslaw]

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[parkie83]

Thanks holmslaw.

That's what I originally planned to do - but the installation instructions say to use 1.5mm cable for the oven and 2.5mm for the hob. I was getting confused as to how I could go down from 6mm to these cable sizes and still protect the cables with suitably rated fuses.

One other quick question - should I change the 40A MCB in the CU to 32A as 40A is the current rating of the 6mm cable. Or will this likely lead to nuisance tripping given the potential combined power of the hob and oven?

Any helpful advice much appreciated. Thanks

 

[holmslaw]

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[ban-all-sheds]

That's what I originally planned to do - but the installation instructions say to use 1.5mm cable for the oven and 2.5mm for the hob. I was getting confused as to how I could go down from 6mm to these cable sizes and still protect the cables with suitably rated fuses.

For the oven you'll be able to use 1.5mm² because it'll be plugged in.

The oven won't though, and as well as not following the manufacturer's instructions (a contravention of the Wiring Regulations) you may genuinely not be able to safely get 6mm² conductors into terminals designed for 2.5mm².

This is one of the drawbacks of buying appliances which are designed with fundamentally different domestic installation designs from the ones in this country. (I think I can safely predict that they are from manufacturer(s) of mainland European origin?)

You may find that the only safe way you can connect the hob is to drop the rating of the circuit so that you can use a smaller cable, but then you may find that it won't support both appliances.

What voltage is assumed for those power ratings?

Do the instructions specify a current rating for the hob circuit?

What type of 2.5mm² cable is specified for the hob?

 

[holmslaw]

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[ban-all-sheds]

Please explain how pointing out that not following the manufacturer's instructions is a contravention of the Wiring Regulations is illogical scaremongering nonsense.

Please explain how observing that appliances not designed with the expectation of the UK traditional single cooker circuit, or designed with the expectation of 16A socket circuits, can have installation drawbacks is illogical scaremongering nonsense.

As you agree that it might be impossible to safely get 6mm² conductors into terminals designed for 2.5mm², please explain why it is illogical scaremongering nonsense to say that the OP may find that the only safe way to connect the hob would be to drop the rating of the circuit to allow smaller conductors to be used.

Please explain why asking the following questions:

• What voltage is assumed for those power ratings?
• Do the instructions specify a current rating for the hob circuit?
• What type of 2.5mm² cable is specified for the hob?

is illogical scaremongering nonsense.

 

[holmslaw]

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[ban-all-sheds]

134.1.1

So why was it illogical scaremongering nonsense to say so?

 

[ban-all-sheds]

Apparently holmslaw can't come up with any reason whatsoever why what I wrote was illogical scaremongering nonsense.

 

[holmslaw]

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[ban-all-sheds]

I doubt that anyone here, including you, actually believes that.

 

[parkie83]

Sems to have gone a bit off-topic here

ban-all-sheds - the answers to the questions in your earlier post are:
The voltage for the power ratings is 230V
The current rating for the hob is 26A and for the oven it's 13-14
The cable specified is H05VV-F 3 x 2.5mm for the hob and 1.5mm for the oven

Ideally I don't want to put the oven on the existing kitchen ring as I've had that signed off by building control and don't want to go through the whole testing and inspection process again for that circuit. Unless it can't be done safely, I'd like to connect both the hob and oven to the existing 6mm cable that is currently protected by a 40A MCB (which holmslaw says is ok). Is this possible? Thanks

 

[jj4091]

Yes but connect the oven via a separate 13Amp switched fcu spurred off the cooker switch.

 

[ban-all-sheds]

Sems to have gone a bit off-topic here

Complain to Admin.

The cable specified is H05VV-F 3 x 2.5mm for the hob and 1.5mm for the oven

Oven cable is fine - hob one is right on the limit at full load current, but it won't draw that for long (if ever) - guess the maker has done his homework on the likelihood of short duration overloads.

Ideally I don't want to put the oven on the existing kitchen ring as I've had that signed off by building control and don't want to go through the whole testing and inspection process again for that circuit.

The suggestion was to use the cooker outlet to supply a socket to plug the oven into, not to plug it into an existing socket. It's the former which would be notifiable (new socket), not the latter.

Unless it can't be done safely, I'd like to connect both the hob and oven to the existing 6mm cable that is currently protected by a 40A MCB (which holmslaw says is ok). Is this possible? Thanks

Oven yes, by installing a socket on the cooker circuit.

Hob - problematic. The maker says to use 2.5mm² cable, so it's likely that he's designed his terminals to only take conductors that size, and you cannot have a 2.5mm² cable protected by a 40A MCB. But OTOH, if you use a larger cable so that it's safe on a 40A circuit it may not be possible to safely connect it to the terminals on the cooker if it's too big and won't fit properly.