Installing induction hob+electric oven...separate circuits or same?

[les24preludes]

How a cable is installed is called the installation method. The installation method is a factor that determines the current carrying capacity of the cable. One of the worst installation methods with regards to current carrying capacity is when the cable is run through or touching insulation. Do you know how your 6mm oven supply is installed so we can get a better picture of the current carrying capacity of the cable to aid further advice?

You're talking about the existing "cooker" supply here? It will be used for the induction hob, not the oven. From the fuse box (45 amp fuse) there is about 8 metres of twin and earth going to the switch with neon. About 4 metres goes along brick wall and 4 metres in stud wall. Then from the switch above the worktop, about 1.3 metres to the junction box under the worktop. Is this what you want to know or can I gave you any more info?

This is all really helpful, guys.

 

[Dave OCD]

Good points. The 45 amp circuit comes from the fuse box, where there's a 45 amp fuse, into a wall mounted switch with neon (no fuse). The wiring here is 5mm OD overall including insulation - I haven't looked up specifications yet to determine if this is 6mm or 10mm. Should be 10mm, so I hope that's right. The same diameter wiring goes down to what looks like a 45 amp junction box on the wall under the worktop. This is a usual single size junction box, i.e. 850x850mm.

If the supply were split into hob and oven, I'm thinking it would need a larger 3-way junction box. I'm expecting the 5mm OD cable to be 10mm, and from there it would go to a 6mm for hob and 2.5mm for oven. The butyl cable to the hob is 15mm OD including insulation - pretty solid.

That's some junction box, probably bigger than the frontal area of an oven. I think you may mean 85mm x 85mm...

 

[Leesparkykent]

You're talking about the existing "cooker" supply here? It will be used for the induction hob, not the oven. From the fuse box (45 amp fuse) there is about 8 metres of twin and earth going to the switch with neon. About 4 metres goes along brick wall and 4 metres in stud wall. Then from the switch above the worktop, about 1.3 metres to the junction box under the worktop. Is this what you want to know or can I gave you any more info?

This is all really helpful, guys.

Sorry I thought you wanted to know if the existing supply was adequate for both the oven and hob? The 4 meters that goes through a stud wall do you know if its packed with insulation?

 

[Octopus]

Have you got the oven? does it come with a cable? and if so does it have a plug attached?

 

[telectrix]

Looked again, and you're right - the earth wire is solid. Pretty much confirms that the "cooker" supply is 6mm, so 32 amp. So hob only.

NO. unless the 6mm cable is run through insulation, it will handle both hob and oven with ease.

 

[Dave OCD]

On the other hand if it's easy to run a seperate oven supply and ideally via separate RCDs or RCBOs you have the advantage of still having one cooking appliance operational should one develop a fault and 'trip' the RCD or OCPD.

 

[telectrix]

On the other hand if it's easy to run a seperate oven supply and ideally via separate RCDs or RCBOs you have the advantage of still having one cooking appliance operational should one develop a fault and 'trip' the RCD or OCPD.

always the negative waves, moriarty, always the negative waves. woof, woof.

 

[Dave OCD]

always the negative waves, moriarty, always the negative waves. woof, woof.

Are you p155ed ? I thought my post was positive, you'd want things designed as well as possible in your own house ?

 

[telectrix]

he cast out his hook and got a bite within seconds,

 

[Midwest]

How time flies.

 

[Midwest]

After all that kerfuffle, I still think the best advice is get an electrician in Les, before you have an accident

 

[les24preludes]

Just took a break to get other parts of the refit together.

Coming back to this, I think the answer is to use the existing 6mm "cooker" feed for the hob, and get an electrician to fit another 6mm feed from the fusebox for the oven, with its own fuse. That covers all the safety needs, and leaves a little extra capacity.

 

[kropaske]

Just took a break to get other parts of the refit together.

Coming back to this, I think the answer is to use the existing 6mm "cooker" feed for the hob, and get an electrician to fit another 6mm feed from the fusebox for the oven, with its own fuse. That covers all the safety needs, and leaves a little extra capacity.

Check the oven manual as well as often manufacturers require max 16/20amp PD for those ovens. So you may well comply with regs but not with manufacturer guidelines...

 

[Midwest]

Check the oven manual as well as often manufacturers require max 16/20amp PD for those ovens. So you may well comply with regs but not with manufacturer guidelines...

I might be wrong, but I thought ocpd were for the benefit of the cable they are supplying, not any appliance that's connected to it. Manufacturers instructions should now only be taken into consideration.

 

[kropaske]

I might be wrong, but I thought ocpd were for the benefit of the cable they are supplying, not any appliance that's connected to it. Manufacturers instructions should now only be taken into consideration.

Correct
But if they ask for one I would certainly fit one.

 

[Andy78]

Correct
But if they ask for one I would certainly fit one.

Even if it was completely unnecessary ?

 

[Midwest]

I'm not sure how providing a reduced ocpd for an oven for example might work, with all the different devices fitted internally, having different loads etc, to provide overload protection for the appliance. Have to say I've never seen this, only other than the manufacturer stating the minimum supply required?

 

[Andy78]

I'm not sure how providing a reduced ocpd for an oven for example might work, with all the different devices fitted internally, having different loads etc, to provide overload protection for the appliance. Have to say I've never seen this, only other than the manufacturer stating the minimum supply required?

The only reason I can think of would be to protect a flex supplied already connected to the appliance.

 

[Midwest]

Although an oven doesn't have a fixed load, one assumes the manufacturer would install a supply cable suitable for it's maximum load?

 

[Andy78]

Although an oven doesn't have a fixed load, one assumes the manufacturer would install a supply cable suitable for it's maximum load?

I have seen pre wired flexes with a CCC smaller than the total connected loads. I assume the manufacturer based the cable size on the diversity due to the cycling of the loads built in to the appliance.