All electric cooker

[morqthana]

At the minute I use 12m of 6mm2 twin/earth cable (going through insulated joists) starting with a B32 RCBO going to a 45A DP switch which then goes to a 45A cooker outlet which is behind the existing gas hob/electric oven cooker.

I'm looking to future proof for an all electric cooker (electric oven/electric hob). To do this I have already threaded about 10m of 10mm2 twin/earth cable through insulated joists. I will pay an electrician later on to connect the 10mm2 to a B45 RCBO. The 10mm2 cable is about 2m too short to reach the cooker outlet position so I will need to use a 60A junction box (1) located under the floorboards (at half joist depth so 100mm deep), then the 10mm2 cable goes to a 45A DP 1 gang switch (2) (with a 25mm backbox (2.1)) then to a 45A cooker outlet (3)

After completion there will be 2 cooker outlets on the wall behind the existing gas/electric cooker, 1 for existing 6mm2 gas/electric and the other for 10mm2 all electric (future use).

Here's a list of kit I plan to use:

(1) junction box (connects 10mm2 together as original cable not long enough) https://www.screwfix.com/p/knightsb...te/379ya#product_additional_details_container

(2) Kitchen cooker switch https://www.screwfix.com/p/essentials-45a-1-gang-dp-cooker-switch-white/8855d

(2.1) backbox https://www.screwfix.com/p/appleby-1-gang-dry-lining-knockout-box-35mm/44827

(3) Cooker outlet https://www.screwfix.com/p/crabtree-capital-45a-unswitched-cooker-outlet-plate-white/7359k

Can provide pics if needed

For the 45A switch (2) can I reuse a capped off 1 gang socket on the stud(partition) wall adjacent to the existing cooker? The capped off 1 gang socket is a distance from the existing gas/electric cooker of 21cm horizontally, and is 13cm above the 60cm high countertop (aligned with the existing cooker switch)
Does the cooker switch/cooker outlet backboxes need to be screwed into wood within the stud(partition) wall or just plasterboard?
I accidentally shaved about 1mm off the sheath of an adjacent twin/earth cable whilst drilling the holes for the 10mm2 cable - NOTE THAT THE SHEATH IS STILL INTACT NO COPPER IS SHOWING AND THE RCBO DID NOT TRIP. I wrapped electrical tape over the damaged sheath. Is this repair ok?
And for the new cooker outlet (3) does this need to be at the same height as the existing cooker outlet? And say a horizontal separation of minimum 10cm?

I think it's this 45A fixation which is the root of many of your problems. I'd say try using a lower number in your calculator, but it's probably too late.

 

[EFLImpudence]

Also this bit says 90º cable so that's no good anyway.

 

[EFLImpudence]

Reference Method 101 = Above a plasterboard ceiling covered by thermal insulation EXCEEDING 100mm.

Just to rub it in for future reference - - what 101 really means is install the cable another way.

 

[ebee]

Once a chip pan is on fire, what good does turning off the cooker do?

And if a chip pan is on fire, where is the best place to go? Into a room with a chip pan on fire, or out of the house?

Well, one method of fighting/reducing hazards of a chip pan fire might be used is to wring a tea towel and place it over the chip pan to smother the fire for a start, rapid safe shut off immediately prior to or just after is a good way to remove to heat source at the same time

 

[ebee]

Nothing you can normally buy for domestic premises will require more than a 32A circuit.

Clipped direct or buried in masonry a 4mm² cable would be adequate.

I tend to agree with that summary

 

[ebee]

I think it's this 45A fixation which is the root of many of your problems.

Yes good point.

Start at 32A and compare to what you have and consider what you might eventually have and see if it all still tallies with your calcs.
If not then tell us those considerations for further examination.

 

[EFLImpudence]

I tend to agree with that summary

Then you must be tending correctly.

 

[TryAgain1]

Also this bit says 90º cable so that's no good anyway.

View attachment 389096

What temperature is a standard 10mm2 twin/earth rated to? Can't be far off

 

[EFLImpudence]

70º - Far enough.

 

[TryAgain1]

Yes good point.

Start at 32A and compare to what you have and consider what you might eventually have and see if it all still tallies with your calcs.
If not then tell us those considerations for further examination.

Yes good point.

Start at 32A and compare to what you have and consider what you might eventually have and see if it all still tallies with your calcs.
If not then tell us those considerations for further examination.

I ran another calculator, max allowed for 10mm2 with 100mm+ insulation is 36A. So a 36A all electric cooker is max allowed for that 45A DP switch, so about 8 kW.

 

[TryAgain1]

I ran another calculator, max allowed for 10mm2 with 100mm+ insulation is 36A. So a 36A all electric cooker is max allowed for that 45A DP switch, so about 8 kW.

I think it's this 45A fixation which is the root of many of your problems. I'd say try using a lower number in your calculator, but it's probably too late.

 

[pete01]

Try diversity

 

[TryAgain1]

Try diversity

How do I apply the diversity rule of thumb to an all electric cooker? Say I use all 4 hobs (e.g. 5kw so 5,000W/230V = 21.7A ) about 30% of the time (21.7A x 30% = 6.5A and the oven (e.g. 5kw for arguments sake, 5so 21.7A) again 30% of the time (6.5A), so 6.5A+ 6.5A = 13A. Well below the 36A max rated for 10mm2 in insulation.

I could get a 10kw or a 12kw electric cooker power with 30% diversity applied.

 

[pete01]

Watch this, it's a good watch.

 

[securespark]

There are no height regulations for sockets.

Not specifically, but there is a general reg that says you must place equipment where it will not be subject to damage.

So there is a sensible height for sockets, so they don't get bashed into by furniture or vacuum cleaners etc...