2x 16A oven

[Kdminx]

Hi All,

I'm in the planning stages for my new Kitchen and have a question about the electrics for the Ovens. Currently there is a cheapo single electric oven with a 13A plug, plugged into the downstairs ring. There is a 30A cartridge fuse in the consumer unit marked "Cooker" but the fuse has been removed.

In my new Kitchen I'm having 2 separate ovens. Looking at the details they need a 16A hardwired connection each. Will the electrician hook them both up to the 30A "cooker" circuit or will he want to run 2 new 16A circuits?

TIA
K

 

[Taylortwocities]

Yes, both can be connected to the cooker circuit, if indeed it still exists.

The fuse will have been removed for a reason, maybe the circuit is no longer there, or may be faulty.
Your electrician will need to test the wiring to discover this.

 

[ericmark]

Theory says the manufacturer should state the range of supply required, between say 16 and 20 amp, but in practice one normally assumes the standard 32A feed used for cookers is acceptable for ovens and hobs. Only when it goes above 32A is the question raised is the supply too big.

There are other points where theory and practice may not seem to agree, with the provision of RCD protection, and disconnection times of a cartridge fuse.

So in real terms only the electrician signing the paperwork can say if he wants twin or single supplies. Personally I would not worry with two ovens on a 32A supply, but I would question two ovens on a 45A supply.

 

[JohnW2]

Personally I would not worry with two ovens on a 32A supply, but I would question two ovens on a 45A supply.

As a matter of interest, what would be your concern in the latter case?

One potential complication, of course, is that manufacturers of cooking appliances quite often specify a maximum fuse/MCB rating - so, if one feels the need to comply with such instructions, there can be a problem if, as in this thread, one wishes to power two cooking appliances from the same supply.

Kind Regards, John

 

[ericmark]

Unless the manufacturer states "requires a supply no bigger than 16A" then I would assume requires 16A supply refers to the minimum supply however I think it is unlikely it needs 16A rather than 15A so since both 15A and 16A fuses are in common use, one would expect to see requires a 15A supply.

I have looked at a number of specs for ovens, and in the main it would seem you have British at 13A and rest of Europe at 16A and the 16A label is to tell you that a FCU or 13A plug can't be used, rather than say a 20, 25, 30 or 32 amp fuse or MCB is too big. However clearly relying on the 100A incoming fuse is also not acceptable so there has to be a point at which one would say that protection device is too big.

Since for the last 40 years 30 and 32 amp has been considered as the standard size for a cooker supply, I would say unless the manufacturer says to be protected by a device no larger than 16A then it is reasonable to consider a 32A protection device is suitable.

Although some installers have used 45A MCB's for the cooker supply, this is not the industrial standard, so feeding an oven with a supply over twice the size required is really over stepping the mark.

This is however up to the electrician doing the work, and any home owner must realise it is a matter for the electrician who signs the minor works to decide, and any one else with the exception of maybe the scheme provider can't really say if the electrician is right or wrong.

If I came to fit an oven and it seemed likely that a fault could develop which a 32A MCB/RCBO/RCD unit or combination what unlikely to auto disconnect the supply then I would refuse to use a 32A device. In the same way, if the oven was clearly over engineered and was likely to trip a 45A device should a fault develop then maybe I would connect to a 45A MCB, although unlikely.

 

[JohnW2]

... I would say unless the manufacturer says to be protected by a device no larger than 16A then it is reasonable to consider a 32A protection device is suitable.

Fair enough - but, as I said, it seems that a good few manufactures do make such a statement about 'maximum OPD rating".

Although some installers have used 45A MCB's for the cooker supply, this is not the industrial standard, so feeding an oven with a supply over twice the size required is really over stepping the mark.

I realised from what you wrote before that such was your feeling but, as I asked, what is the concern that makes you feel that it is "over stepping the mark"?

In the same way, if the oven was clearly over engineered and was likely to trip a 45A device should a fault develop then maybe I would connect to a 45A MCB, although unlikely.

Are you talking about "fault" in the true sense? If so, then, as you know, a circuit protected by a 45A OPD is required to have a low enough Zs that such a fault would cause that OPD to operate.

Kind Regards, John

 

[EFLImpudence]

Unless the manufacturer states "requires a supply no bigger than 16A" then I would assume requires 16A supply refers to the minimum supply however I think it is unlikely it needs 16A rather than 15A so since both 15A and 16A fuses are in common use, one would expect to see requires a 15A supply.

If a manufacturer states "requires a supply no bigger than 16A" how can that be a minimum?

I have looked at a number of specs for ovens, and in the main it would seem you have British at 13A and rest of Europe at 16A

They have 16A circuits in Europe. Britain usually has 32A for cookers.

and the 16A label is to tell you that a FCU or 13A plug can't be used,

No, it isn't. It means put it on a 16A circuit in Europe. In Britain - work it out yourself.

rather than say a 20, 25, 30 or 32 amp fuse or MCB is too big.

How can it be too big if the manufacturer has not specified an OPD size?

However clearly relying on the 100A incoming fuse is also not acceptable so there has to be a point at which one would say that protection device is too big.

Silly comment.

Since for the last 40 years 30 and 32 amp has been considered as the standard size for a cooker supply, I would say unless the manufacturer says to be protected by a device no larger than 16A then it is reasonable to consider a 32A protection device is suitable.

Of course. So what was the above all about?

Although some installers have used 45A MCB's for the cooker supply, this is not the industrial standard, so feeding an oven with a supply over twice the size required is really over stepping the mark.

Since the removal of a 30A BS3036 fuse, the 6mm² cable is adequate for a 45A MCB.

This is however up to the electrician doing the work, and any home owner must realise it is a matter for the electrician who signs the minor works to decide, and any one else with the exception of maybe the scheme provider can't really say if the electrician is right or wrong.

Right.

If I came to fit an oven and it seemed likely that a fault could develop which a 32A MCB/RCBO/RCD unit or combination what unlikely to auto disconnect the supply then I would refuse to use a 32A device. In the same way, if the oven was clearly over engineered and was likely to trip a 45A device should a fault develop then maybe I would connect to a 45A MCB, although unlikely.

Whatever does that mean?

 

[John D v2.0]

If you're worried the supply is too big, just fuse down further where you spur off the big supply. Might need to resort to a small box with an MCB, but it's still probably cheaper then running a new cable

 

[JohnW2]

If you're worried the supply is too big, just fuse down further where you spur off the big supply.....

Indeed, IF 'one is worried' - but I'm still trying to find out why eric is worried/concerned.

Kind Regards, John

 

[ericmark]

When some one argues very hard either one way or the other, my thoughts are that person has done it one way many times and wants to justify their decision.

I see no real problem either way unless it clearly goes against the manufacturers recommendations. What however I do see as wrong is to tell Joe public that the electrician he has engaged has got it wrong.

My aim was to show there are pros and cons and it is up the electrician signing the paperwork to decide yes or no, not anyone including me on the forum.

 

[JohnW2]

When some one argues very hard either one way or the other, my thoughts are that person has done it one way many times and wants to justify their decision. .... I see no real problem either way unless it clearly goes against the manufacturers recommendations. What however I do see as wrong is to tell Joe public that the electrician he has engaged has got it wrong.

No-one has (yet) engaged an electrician or been told that any electrician has got anything wrong. The OP simply asked how his two ovens could/should be connected.

I see no real problem either way unless it clearly goes against the manufacturers recommendations.

Fair enough - but, if so, why did you say that supplying an oven from a 45A circuit would be 'overstepping the mark" (and implied that you would probably unlikley do that)??

My aim was to show there are pros and cons and it is up the electrician signing the paperwork to decide yes or no, not anyone including me on the forum.

Again, that's fair enough - but if you don't feel that it's your place to decide/advise, why did you jump in, right at the start, saying ".... but I would question two ovens on a 45A supply"??

Kind Regards, John