3.4kw oven and 7kw hob on 32A circuit - advice welcome

[boycie2]

Hello. I currently have a 32A cooker circuit that runs through a cooker switch on the wall to a double socket behind the single oven under the worktops. The oven is 3400w and plugs in. There is also a gas hob that I would like to replace with an induction hob. The induction hobs I have seen that fit the bill are all about 7000w.

There is 6mm cabling that runs to the double socket and I'd replace the double socket with a cooker switch and single socket for the new hob and plug in oven. I can only see me using the oven and all four hob rings rarely (Christmas etc).

My question is, can I safely run my 3400w oven and 7000w induction hob on this circuit? Thanks for any advice.

 

[JohnW2]

There is 6mm cabling that runs to the double socket and I'd replace the double socket with a cooker switch and single socket for the new hob and plug in oven. I can only see me using the oven and all four hob rings rarely (Christmas etc). ... My question is, can I safely run my 3400w oven and 7000w induction hob on this circuit? Thanks for any advice.

The circuit, per se, would be fine. Even if the powers of the oven and hob are stated at 230V (which they probably aren't - they are probably stated for 240V, which makes things 'better'), 10,400W total equates to about 45A total. Applying the concept of diversity (which takes into account the fact that not all parts of the cooking appliances will be drawing current simultaneously for long periods), we are allowed to consider that as a load of about 20.5A - plenty low enough for both a 32A circuit and 6mm² cable.

The hob will need to be connected via a 'cooker outlet plate' fed from the new cooker control unit ('cooker switch'). If you are happy for the oven to be plugged in above counter level, you can get cooker control units which incorporate a socket. If you want the oven connection to be 'hidden', you could use a 'dual cooker outlet plate' to feed both the hob and a socket for the oven (e.g. behind the oven).

Kind Regards, John

 

[boycie2]

Thanks for getting back to me so quickly. There is a 45A cooker switch on wall above the worktops (no plug socket). This then is wired through the wall to the double socket behind the over.

As the power supply is okay, I would replace this double socked with a 45A Cooker Switch with 13A Switched Plug. The new hob will be wired directly into this switch and then the oven will plug into the socket. So would this be okay:

Consumer unit >>> 45A cooker switch (on wall) >>> 45A cooker switch + 13A plug >>> oven and hob

 

[JohnW2]

Thanks for getting back to me so quickly. There is a 45A cooker switch on wall above the worktops (no plug socket). This then is wired through the wall to the double socket behind the over.

Are you saying that the present cooker switch is in a different room ("wired through the wall")?

As the power supply is okay, I would replace this double socked with a 45A Cooker Switch with 13A Switched Plug.

If the answer to the above is 'yes', then I suppose that would probably be the simplest way (using 6mm² cable), even though there would then be a 'redundant switch'. Normally, if the existing 45A cooker switch were in the kitchen close to the appliances, one would simply replace the cooker switch without a socket to one which also had a socket (or, even better, as I suggested before, have a socket for oven, fed from the cooker switch, below counter level).

The new hob will be wired directly into this switch and then the oven will plug into the socket. So would this be okay:
Consumer unit >>> 45A cooker switch (on wall) >>> 45A cooker switch + 13A plug >>> oven and hob

Electrically speaking, that would work, but the conventional way would be run a cable from the new cooker switch down to an 'outlet plate' behind the appliances for the connection to the hob (rather than wiring the hob directly into the cooker switch). As I said before, similarly for a socket for the oven ... but those are all largely matters of aesthetics - your method has the leads to both oven and hob visible (and, theoretically, exposed to 'damage') above counter level..

Kind Regards, John

 

[ericmark]

It is not normal to plug in an oven over 3kW likely even at 3400w it will not blow the fuse in a plug in free air. Behind the oven depends on cooling fans if the ovens fans keep it cool then likely a 13A fuse will hold even at 14.8A but fuses tend to weaken over time when taken to the limit there is a risk it could blow although small and so having it inaccessible could be a problem.

To have a plug and socket arrangement so the oven is easy to remove for maintenance is a good idea but personally I would either want to be able to access plug without removing oven or for it to be a type without a fuse inside.

Having a FCU feeding a 15A plug or the socket when you can reach it.

 

[JohnW2]

It is not normal to plug in an oven over 3kW likely even at 3400w it will not blow the fuse in a plug in free air.

Many such ovens come with a fitted plug, and I'm sure that millions of them are 'plugged in'. 3400W at 240V corresponds to only 11A (at 230V) after diversity.

Kind Regards, John

 

[boycie2]

Hello and thanks again for the responses. The oven and switch are in the same room, sorry for the confusion. The oven is a Samsumg and came with a plug attached. We've had it for about 3 years with no problems.

 

[JohnW2]

Hello and thanks again for the responses. The oven and switch are in the same room, sorry for the confusion.

Thanks for clarifying. Is the switch fairly close to the position of the oven and hob - as I said, if it is, you could just swap it for a cooker switch + socket thingy, rather than add a second switch.

The oven is a Samsumg and came with a plug attached. We've had it for about 3 years with no problems.

... as I said, like millions of others!

Kind Regards, John

 

[AndyPRK]

Thanks for clarifying. Is the switch fairly close to the position of the oven and hob - as I said, if it is, you could just swap it for a cooker switch + socket thingy, rather than add a second switch.

A single oven switch will either be 1 gang (square) or 2 gang portrait mounted. Therefore it is not easy to fit a switch and socket in its place.

Also would you want the oven flex coming out of the work top being plugged in there ? I wouldn't.

I think the OP's solution is very cleaver. And worth consideration to others who have ovens that shouldn't be directly connected to a 32A supply.

 

[JohnW2]

A single oven switch will either be 1 gang (square) or 2 gang portrait mounted. Therefore it is not easy to fit a switch and socket in its place.

Maybe. Wee don't actually know what this switch is - in particular, its vintage.

Also would you want the oven flex coming out of the work top being plugged in there ? I wouldn't.

As I've implied to the OP, I definitely wouldn't - but I got the impression, perhaps wrongly, that this was what the OP was proposing and/or wanted. He certainly hasn't contradicted me when I've suggested that was what he was proposing.

I think the OP's solution is very cleaver. And worth consideration to others who have ovens that shouldn't be directly connected to a 32A supply.

If he's planning on having the new CCU with socket below counter level, you could be right - other than that it leaves a redundant ('extra potential point of failure') switch in circuit. In that situation, effectively what he would be doing was using a CCU-with-socket as an alternative to an outlet plate plus a socket - which I suppose would be marginally simpler. As I've said, I personally think an even better solution (avoiding a redundant switch) would be to retain the present 45A switch (assuming it's in a sensible place) and use it to feed a dual outlet plate, which, in turn feeds the hob and a socket for the oven.

Kind Regards, John

 

[AndyPRK]

It would be a redundant switch however if others were to fit it in the cupboard next to the oven (rather than behind) then it's a very simple way of isolating one appliance should it fail. This would leave one cooking appliance working.

 

[JohnW2]

It would be a redundant switch however if others were to fit it in the cupboard next to the oven (rather than behind) then it's a very simple way of isolating one appliance should it fail. This would leave one cooking appliance working.

I can't disagree with that (but there would still be a 'redundant switch )

Kind Regards, John

 

[AndyPRK]

Well actually 2.

One for oven and one for hob. I would be glad to have them though when an element went.

 

[ericmark]

From reply overload is not a problem. However with closed door grilling some ovens use two elements together my stand alone cookers oven does my mothers built in oven time shares and to be honest it's closed door grilling is hopeless.

In fact we are thankful now we did not get built in units as also her hob was useless it had silly touch controls which were much slower to operate than knobs so one had to lift a pan to stop it boiling over rather then simply turn it off and my mother in her wheel chair could not see the controls they could not be viewed at that angle. As a result the hob had to be ripped out.

Maybe if our own did not have knobs we would not realise how much better knobs are? Before induction electric hobs were slow to react so having slow touch controls did not affect the use and made them easy clean. But with induction it's easy clean anyway and the human machine interface needs to be fast enough so you don't need to lift the pan and most touch controls need more than one touch so are simply too slow.

 

[JohnW2]

Well actually 2. One for oven and one for hob. I would be glad to have them though when an element went.

I suppose one could make it two, but IMO not those two. I agree that it is desirable (hence non-redundant) to be able to isolate the oven and hob separately. However, since isolation of the oven can be achieved by pulling the plug out, the associated switch would be technically redundant - as would be the other 45A switch upstream of all that.

However, we're quibbling - any of the options we're considering would be fine, and could be found in many a kitchen.

Kind Regards, John