Induction hob, oven and combi microwave wiring

[Em01]

Hi, I have bought replacement appliances for my kitchen and I will install them in virtually the same place as the existing double oven and ceramic hob, so the position of the existing wiring does not need to be changed. However, I am unsure if I need to get an electrician in to change the wiring configuration.

Current wiring:
From the mains board, on RCD circuit, one 6mm^2 T&E cable runs through the ceiling to the kitchen and terminates in a cooker switch. The fuse says B40 on the mains board. From the cooker switch one 6mm^2 T&E runs into a round brown junction box and from there one cable runs to the double oven and another runs to the hob. Does that all sound ok? I was a bit surprised to see an ordinary junction box?! This wiring was done by an electrician 19 years ago.

Required Wiring:
To replace the double oven I now have a separate combi microwave and oven and therefore two cables to accommodate (plus the one from the hob). I have been reading numerous forum entries but I cannot find a definitive answer. I don't mind calling an electrician out, but if it is as easy as running another cable into the junction box then I am more than happy to do that (presumably that does not fall under ceritifiable changes?).

Power ratings:
Combi microwave 3kwh
Oven 3.4 kwh
Induction hob with extractor 7.62 kwh

Your advice would be really appreciated!
Em

 

[JohnD]

The microwave could go into a socket with a 13A fused plug.

The round JB is wrong.

The cable from the switch ought to go into a wall-mounted cooker outlet. They have nice big terminals and will accommodate an oven and hob, also have cable grips to prevent tugging loose, and the front shape prevents dirt or liquid falling inside.

Some examples on here
https://www.tlc-direct.co.uk/tcl/search?query=Cooker+outlet&Submit=Search

I favour Crabtree but get a major British brand.

The internals are very big and the thick cables stiff so you need an extra-deep backbox. 35mm might do but 44mm is better.

Retighten the terminal screws after a week because the stranded soft copper cores will deform under the big screws and may become loose. Try them again after a month. This is always a good tip with big cables. Electric shower switches are notorious for loose connections.

 

[EFLImpudence]

Just to say - yes, you could do as you have suggested - not ideal but electrically alright.

 

[Em01]

Thank you very much John, I really appreciate your advice!

So, next to the cooker switch is a double socket on a mains ring, would it be a good idea to add a spur to this to hard-wire the microwave in? Or is it permissable to have a socket below the work surface? I would like to avoid cluttering the work surface.

Thanks again
Em

 

[Em01]

Just to say - yes, you could do as you have suggested - not ideal but electrically alright.

Hi, is this in reply to me or John's suggestion? The old junction box really doesn't feel right, John's suggestions makes sense?

Em

 

[EFLImpudence]

Sorry. It was in reply to you and your original suggestion.

 

[Em01]

Sorry. It was in reply to you and your original suggestion.

Ah yes I thought so but wasn't sure. I'm curious, if you say it is electrically correct, does that mean I could run all three cables into the double outlet that JohnD suggested? Is that kind of like a junction box? It would save having to find a socket for the microwave.

Thanks!
Em

 

[EFLImpudence]

I'm curious, if you say it is electrically correct, does that mean I could run all three cables into the double outlet that JohnD suggested? Is that kind of like a junction box?

Yes, you have to have the connections somewhere.