Kitchen wiring for hob and oven

[robocod]

Hi all, I recently purchased a house with an old but usable kitchen. The electric hob was very old, knackered and an odd size. It was hard wired, but only 2.6kw. The eye level built in oven had been replaced with a built under (with feet), also hard wired. Both hard wired to the junction box. Some changes had been made to the original wiring, long before I arrived. Very rough pictures below (I know, they are horid ).

I'd like to replace the electric hob with a plug in model, to be plugged in under the counter. The aim being to lower power consumption, to help with the power diversity on the single 32amp feed.

The main question here is can I run a fused spur from the existing junction box and then from that fused spur to a 13amp socket for the hob? The kitchen fitter suggested no, but have yet to speak to a sparkie.

Cheers!


Existing wiring.

Proposed wiring.

 

[chivers67]

What power ratings are the new Oven and Hob going to be? What is the point of the Fused spur here?

 

[robocod]

What power ratings are the new Oven and Hob going to be? What is the point of the Fused spur here?

The hob will be a Bosch 13amp plug in kind, not hard wired, so in the region of 3kw, designed for a standard plug. The oven will be in the region of 4.3kw. I haven't finalised my plans yet as I wanted to make sure what I imagined was sensible. The kitchen fitter replacing the worktops suggested I might need to rewire the entire oven/hob circuit to make it "safe". That said, it passed a EICR in 2020 when it was a rental property.

I considered the fused spur would be necessary, but I'm no expert, hence I'm here asking I assume I might be able to dispense with the fused spur as the socket is by its very nature a means of isolation.

Thanks for your time

 

[AndyPRK]

I'd go with a full powered hob. You have a 32A supply.

in the unlikely event you have problems, some hobs have program options to limit their current anyway. or just don't use as many 'hot plates'

 

[Taylortwocities]

My thoughts

I'd like to replace the electric hob with a plug in model, to be plugged in under the counter. The aim being to lower power consumption, to help with the power diversity on the single 32amp feed.

I'm trying to understand your logic here. Plug in hobs (max 13amp) have poor performance compared to their larger (hard-wired) cousins. The only reason (that I can think of) for as plug in hob is when there isn't a largish power source available, and you have one. The 32A "cooker" circuit is made for it! EDIT:Just seen post from @AndyPRK making the same point.

The kitchen fitter replacing the worktops suggested I might need to rewire the entire oven/hob circuit to make it "safe"

Oh dear. Complete cobblers! That's why he/she is a kitchen fitter.

I assume that the graphic for the cooker switch shows one that you have, ie cooker switch plus a socket all in one plate?

Assuming you go for hard-wired hob and oven, then all you need is one of THESE connected to the (I guess) 6mm² cable that runs to your junction box (throw that away). Wire your two appliances in, thats all you need to do.

 

[pete01]

You can have upto 15kw of cookers and hobs etc on a 6mm 32 amp circuit.....some say 20kw.

 

[EFLImpudence]

You can have upto 15kw of cookers and hobs etc on a 6mm 32 amp circuit.....some say 20kw.

Yes - 15 or 20 depends on whether there is a socket as part of the cooker switch.

 

[robocod]

Thank you all for the replies, this is all very informative and I appreciate your insight. Perhaps the kitchen fitter was being a little alarmist, he did suggest I'd probably find a sparkie happy to do whatever, but he just wouldn't be happy with it himself.

The existing hardwired 32amp feed for the cooker/hob runs to one of these at the wall;

Then into one of these, where it splits out the oven/hob all on what looks very much like 6mm.

Based on what you guys are saying, I'll go for a hard wired hob. There is a 5 kw Beko with actual knobs(!), which I think would be a better choice than a touch screen for my elderly mother.

Would it be best to remove the black junction box and change it to a 45A Dual Connection Plate as mentioned by Taylortwocities? Or is it safe enough to use the existing arrangement?

Cheers!

 

[EFLImpudence]

Would it be best to remove the black junction box and change it to a 45A Dual Connection Plate as mentioned by Taylortwocities? Or is it safe enough to use the existing arrangement?

A connection plate would be better.

 

[Taylortwocities]

Would it be best to remove the black junction box and change it to a 45A Dual Connection Plate as mentioned by Taylortwocities? Or is it safe enough to use the existing arrangement?

Those round brown junction boxes have a max cable connection capacity of two 6mm² cables. you'll need three, that's why 45A Dual Connection Plates were invented!

 

[robocod]

Those round brown junction boxes have a max cable connection capacity of two 6mm² cables. you'll need three, that's why 45A Dual Connection Plates were invented!

After isolating the power I did inspect inside the brown junction box, the wiring was somewhat unconventional. The 6mm had been removed of some of it's insulation in the middle, to allow each conductor to be screwed into the junction box terminals, with the still insulated tails going off to each appliance. I suspect that was probably a DIY job or predates dual connect plates.

This is all good information, thanks again. I can now have a somewhat informed conversation with a sparkie

 

[EFLImpudence]

The 6mm had been removed of some of it's insulation in the middle, to allow each conductor to be screwed into the junction box terminals, with the still insulated tails going off to each appliance.

A very good idea which negates Taylor's worry in post #10.

I suspect that was probably a DIY job or predates dual connect plates.

Not necessarily either.

 

[robocod]

A very good idea which negates Taylor's worry in post #10.

Ah so that wasn't anything to worry about then?

 

[Taylortwocities]

A very good idea which negates Taylor's worry in post #10.

I'd forgotten that the appliance cables are a lot smaller than 6mm!

 

[EFLImpudence]

I'd forgotten that the appliance cables are a lot smaller than 6mm!

No it is not that.

The point is that with the method used there are only two conductors in each junction box terminal.