wiring 20amp oven and 20amp hob

[williamdjackson]

Evening all,

New kitchen means new double oven and induction hob. I have the old style wylex consumer unit with one spare 32amp breaker which I think was used to supply a shower or immersion heater previously (shower now mains off combi boiler)

Can I use this to connect the new hob and oven? I think the wire is either 4mm or maybe 6mm and is currently being used for the security alarm!?! Was hoping to come off the ring main for the alarm and then run the wire from the old shower/immersion into the kitchen to supply the oven and hob.

Both the oven and hob are rated at 20amp each. If I use diversity this comes in at 24amp with the 5amp socket allowance.

Is 4mm wire ok or will it need to be 6mm?

Alternatively I could install a gas hob and just run the oven from this.

Many thanks.

 

[DaftPunk]

Are any of your new cables going to be installed within a wall or partition?

 

[williamdjackson]

Hi,

Wire will run above ceiling and then I'll chase into kitchen wall. Having a new full new kitchen installed so can nock it around however I like.

 

[DaftPunk]

Oh right, in that case then, regulations require you RCD protect all the new wiring, so that old wylex will have to go I'm afraid.

Also with an installation of that age, you'll need to check that main bonding is in place and up to spec..

As you'll be getting a new cu you can use what ever size cable and circuit breaker best suits your new oven and hob.

Depending on the run and the way it is installed, I'd expect to use 6mm cable for this, but you would need to do proper cable calls to verify this.

 

[williamdjackson]

Ah, right.

Is there any way to do it without having to bin the wylex?

Imagine if the wiring was already in place as described above, would it be suitable to run the new 20amp hob and 20 amp cooker?

 

[ericmark]

There are special cables which can be used in a wall without RCD protection to BS 8436 also RCD's can be fitted in shower of garage supply units

how really is dependent on what you have. One would expect any shower supply to be already RCD protected and be using at least 6mm cable so should not need any additions.

Although regulations say must be RCD protected or special cable if buried in a wall since the cooker and hob don't need RCD protection you do need to use some common sense.

As to induction hob have installed one in my house and mothers mine is great but mothers was a problem and not the induction bit but use of touch controls. With non induction there was a move to touch controls as easy clean but not required with induction and the whole idea of induction is reaction speed and one just can't use touch controls quickly. So pan starts to boil over no my hob and I don't touch pan I just turn it down but with mothers it takes so long to turn down have to lift pan off hob. Also angle of view since she is in a wheel chair she can't see touch controls the same would apply to children. So learn from my mothers mistake do not get one with touch controls get one with simple knobs.

The induction hob is fast and safe my son and daughter use gas and daughter boils water in electric kettle then pours boiling water into pan as she said it was quicker. Kettle 2.8kW and ring 5.5kW I said can't be right so she did a demo and was correct kettle beat gas hob by near 2 to 1 ratio. (Lid was on pan) So on return home did same with 3kW induction and 2.8kW kettle and boil time was same with both methods. So a 3kW induction hob puts more heat into the pan than a 5.5kW gas hob. Clearly the heat goes else where and in summer my daughters kitchen is like a sauna but ours is only a little warmer than rest of house as heat goes into food not to warm kitchen.

Also noted humidity father-in-law next door but one in same design house kitchen around 75% compared with ours at 45% all down to induction hob v gas hob.

Add to that things like child lock, and auto switch off if forgotten I would not permit the install of a dangerous gas hob with non of the induction safety features. However wife is not amused when I forget to remove child lock when grand children leave.

 

[AndyPRK]

4mm cable is not suitable for 32A

A dual outlet plate off eBay is recommended as it makes the job easy connecting the hob and oven up.

You will need an isolator switch too 45A
Without 13A socket is best.

 

[williamdjackson]

Thanks for the info guys. Very useful. I'm going to take a look today and see what size the wire is into the CU.

If it turns out to be 4mm, would it be acceptable to use it to run the oven only on a 20amp breaker? If so, we'll be ordering the gas hob!

Many thanks in advance

 

[xr4x4]

If you don't want to replace the old cu.

Get a second new cu installed along side the old and run new circuits off this.

 

[EFLImpudence]

4mm cable is not suitable for 32A

Yes, it is when using MCBs.

6mm² was used only because of the derating necessary with 30A re-wireable fuses.

 

[EFLImpudence]

If it turns out to be 4mm, would it be acceptable to use it to run the oven only on a 20amp breaker?

As long as it runs through NO thermal insulation NOR conduit -

It, 4mm², will be fine with 32A MCB and both oven and hob.

 

[williamdjackson]

Thanks all,

Had a look and it's a 6mm wire which used to run the old shower so should be able to utilise it. I'll get a qualified electrician in to carry out all the necessary works and job's a good 'un.

thanks again.

 

[AndyPRK]

Had a look and it's a 6mm wire which used to run the old shower so should be able to utilise it. I'll get a qualified electrician in to carry out all the necessary works and job's a good 'un. Now where did I put my wire cutters....

thanks again.