Best way of spuring off a cooker circuit for 13AMP microwave

[davidr]

Hi

I want to swap a built-in double oven for a separate single oven (3.6KW) and combination microwave (3KW) both of which will be built into to same space and connected to my 30AMP cooker circuit.

The existing wiring is a 30AMP MCB radial circuit to 45AMP cooker switch/socket (MK) with buried 10mm T&E to back of oven housing.

Complexity arises due to new microwave requiring a 13 amp socket whereas single oven requires 6mm T&E connection. I have no easy way of getting a ring main spur to the back of the microwave.

Question:

Is it ok to add a second MK oven switch/socket (K5040WHI) behind the built-in cabinet to feed both devices from the existing 45 AMP switch?

All cable will be 10mm T&E (apart from the flex to the microwave) and I'll end up with two cooker switches in series with the load on the accessible one feeding the hidden second one into which both devices are connected?
The hidden one will always be left on - cooker and socket.

Creating a new spur off the kitchen ring with isloating switch for the microwave combination oven is difficult as it will require removing tiling.
I also don't like the idea of a normal 13AMP socket spur with 10mm cable.
I understand this is ok with regs provided all cable is same size.

Max load on the new circuit would be 16 AMP (single oven) + 12.5 (microwave) + 13 AMP for visible socket = 42 AMPs.

I'd probably use a K5045WHI for the 10mm buried cable outlet.

Is this ok or am I being stupid? Should I get an electrican to upgrade the MCB or leave it at 30AMP?

Thanks for your advice

 

[Chri5]

You shouldn't spur off the cooker point.

the loading and fuse rating have been designed as a stand alone circuit.

Yes, it will work- what happens if in a while you change the oven to a more heavy load ?

Spur from the kitchen ring for the microwave or use the socket on a cooker isolator with a socket in built.

 

[ban-all-sheds]

You shouldn't spur off the cooker point.

It's a circuit for cooking appliances, so why not?

the loading and fuse rating have been designed as a stand alone circuit.

And provided it's properly designed it can't be unsafe.

If this was a case of a separate oven and hob would you say that they couldn't go on a cooker circuit?

Yes, it will work- what happens if in a while you change the oven to a more heavy load ?

What happens if he changes everything for an integrated free-standing 16kW range cooker?

Spur from the kitchen ring for the microwave or use the socket on a cooker isolator with a socket in built.

From a circuit loading perspective, how does the latter differ from putting an FCU on the circuit?

 

[Chri5]

BAS- splitting hairs again

I consider a microwave as an appliance, next you suggest that running a dish washer is acceptable via the same cooker circuit.

To keep the integrity of the circuit design I consider it good practice to use it as intended, I also assumed the poster didn't want to call in a Part P person and hence the suggestion of using a cooker point with integrated plug to handle the microwave would be a non part P job- provided the cooker point has a socket.

Does that agree with your logic boxes

 

[davidr]

Thanks guys. To be clear, I'm ONLY interested in doing this properly and safely and will happily call in a Part P registered electrician to inspect and approve the work.

My question was more whether it was dangerous or in any way wrong to have two isolation swtiches - one after the other - one hidden, one visible? This is only because I don't see how I can easily get 10mm T&E into the back of an ordinary single socket.

Diagram might help explain what I'm proposing:

Appreciate your thoughts on this.

 

[davidr]

Untitled

• davidr
• 9 Dec 2008
• 2

 

[ban-all-sheds]

BAS- splitting hairs again

Hardly.

I consider a microwave as an appliance,

So do I - a COOKING appliance....

next you suggest that running a dish washer is acceptable via the same cooker circuit.

Did I?

Where?

To keep the integrity of the circuit design I consider it good practice to use it as intended,

You mean for COOKING appliances?

I also assumed the poster didn't want to call in a Part P person and hence the suggestion of using a cooker point with integrated plug to handle the microwave would be a non part P job- provided the cooker point has a socket.

It does have one, but the OP has clearly decided he doesn't want to use it...

Does that agree with your logic boxes

No.

 

[ban-all-sheds]

Thanks guys. To be clear, I'm ONLY interested in doing this properly and safely and will happily call in a Part P registered electrician to inspect and approve the work.

That's not how it works....

//www.diynot.com/wiki/electrics:part-p

My question was more whether it was dangerous or in any way wrong to have two isolation swtiches - one after the other - one hidden, one visible?

You'd have an accessible means of isolation. so that's OK.

This is only because I don't see how I can easily get 10mm T&E into the back of an ordinary single socket.

It wouldn't be easy. It would probably go in, but equally probably would not be what the manufacturer specifies.

 

[davidr]

Wow ! seem to have kicked-off a bit of a debate !

Thanks BAS for the responses.

The microwave "appliance" in question is a Neff built-in combination microwave oven and is physically screwed into a kitchen unit. It is 3KW device and has an ordinary 13A plug. I don't want to have to expose the lead out the back, around the side of the unit and plug it into the visible socket on the cooker isolator - this would be very untidy. I'd prefer to have it plugged in behind, hidden away but still isolatable via the existing cooker isolation switch.

I agree with BAS - this is a cooking device, if I had bought a single combination double oven there would be no issue - the fact that I have chosen two separate devices (with total rating same as a double oven) should not mean that I have to create new spurs off the kitchen ring.

Thanks for your help