New 32amp Double Oven

[ScubaCollie]

Hi All, our oven has packed up and just purchased one of these being delivered on Tuesday.

https://www.currys.co.uk/gbuk/house...double-oven-stainless-steel-10175678-pdt.html

However, the new oven is 32amps and needs to be hard wired.

I've done spurs off ring mains and socket changes etc, however have a few questions regarding this.

The old oven was a MFI Diplomat double oven but was plugged into a plug socket.

Ive removed the plug socket and the cable is a lot thicker than 2.5mm looks like 4mm at least and it's being fed from a switched cooker socket switch but doesn't show a fuse on the front face and that's controlled from the CU with a 40amp NSB40.

I've checked the kitchen circuits by isolating at the CU and confirmed that the oven supply is on its own circuit. The hob is a 6 gas burner hob with ignition, however this comes off the kitchen sockets circuit and not the oven circuit.

To clarify the circuit for the oven is 4mm and purely feeds the oven only.

What's the best way to hard wire?

I was thinking swapping out the plug socket behind the oven with a fused spur? As the 'cooker isolation switch' doesn't show any fused part on the face plate?

The cooker switch looks like one of these but in metal?

https://www.screwfix.com/p/british-...N2P2cxWaU8xqFYZUZOBoCWdEQAvD_BwE&gclsrc=aw.ds

Therefore if I remove the plug socket and put in a fused spur instead that would be the best way?

The new oven is 32amp Double oven.

Edit just thinking may be best to change the oven switch above to a fused spur instead? As that's not behind the oven whereas the existing plug socket is? And just fit a blanking plate /junction box in place of the plug socket behind the oven and hard wire I to that?

 

[EFLImpudence]

Forget about (so-called) Fused Spur - Fused Connection Unit.
I don't know why you think that would be suitable.

You need one of these instead of the socket:
https://www.screwfix.com/search?search=cooker+outlet+plate
There is no need for a fuse in the kitchen.

If the cable is 4mm² then the MCB should be 32A - but the 40A might be alright for an oven.
If it is 6mm² which is normal for cooker circuits then the 40A is alright.

The instructions also state:
"ELECTRICAL INSTALLATION: This product requires professional installation to a dedicated cooker circuit (identified by a big red cooker switch) by a qualified installer, such as one of our Team Knowhow experts."
From experience, I am not sure that applies to Currys who will only do it if it matches their tick-list.

The oven is stated as 5.9kW which is 25A but you must add 5A for the socket at the switch so 30A which is fine for what you have.

 

[flameport]

Change the socket to one of these: https://www.screwfix.com/p/lap-45a-unswitched-cooker-outlet-plate-white/61074
which is what the old oven should have been connected to.

No fuse required.
An FCU is useless, as they are limited to 13A.

 

[EFLImpudence]

A view of a Cooker Outlet Plate; it just screws to the back box instead of the socket:

 

[ScubaCollie]

Hi Both thank you very much for your help

The socket is a 2 gang at moment, therefore will need to put a new single backbox in the wall?

Also do those sockets have cable routing holes in the bottom to put the cable from the oven into it?

I've used surface mounted boxes in the past with 20mm conduit and glands but obviously that won't be useful here....

Here are photos of the cooker switch and that feeds the double socket behind where the oven is going.

The cable from the back of the socket was bigger than 2.5mm and I thought 4mm but 'maybe' 6mm as the photo below shows the cooker circuit rated at 40amps...

 

[EFLImpudence]

Fit one of these, then you can have the Cooker Outlet and a socket.

https://www.screwfix.com/p/appleby-dual-35mm-dry-lining-box/22772

With the Cooker Outlet, the oven cable just exits the bottom on the surface held with a cable clamp

 

[ScubaCollie]

Hi Mate i won't be able to use the socket as it will be behind the oven do they do those cooker plates in two gang sizes to save me having to install a new backbox?

Also even though I know the cable feeding that socket is bigger than 2.5mm (I have **** loads of 2.5mm and put it up against it tonight) how do I know if its 4mm or 6mm? As I understand for this new cooker it should be 6mm? The cooker circuit is 40amp MCB therefore max amps for 6mm cable is 41amps therefore providing the Spark originally installed the correct MCB it must be 6mm cable and not 4mm as I originally thought?

I was also thinking of wiring from the back of the new oven to the cooker plate with 6mm (as with spurs you have to use the same size cable as the original circuit) but 6mm can apparently be too thick for a non-static environment I. E moving oven out and in and can fracture the cable? Would it be OK to use 4mm from the back of the oven to the cooker plate I would think not?

 

[ScubaCollie]

Edit ive just taken the drywall socket backbox out and pulled some cable through to see if I can find anything on the sheath.

Its difficult to read but looks like this

Basec 080 BS 6004 6242 Y H 2 x 6 (or maybe a 5??) + 2.5 SOMM PX 93

I don't think they do 5mm cable therefore must be a 6mm?

Also found this inside the drywall...... Picture below, looks like they run short and extended with a terminal block.... Might use some WAGO connectors on there instead to make it more secure?

 

[EFLImpudence]

Hi Mate i won't be able to use the socket as it will be behind the oven do they do those cooker plates in two gang sizes to save me having to install a new backbox?

A Cooker Outlet and blank plate, then.

Also even though I know the cable feeding that socket is bigger than 2.5mm (I have **** loads of 2.5mm and put it up against it tonight) how do I know if its 4mm or 6mm?

6 is bigger.
https://www.diynot.com/wiki/Electrics:flatpvccables

As I understand for this new cooker it should be 6mm?

Not really, it is 25A therefore 2.5mm² is adequate, BUT that raises the issue of the protection.
It might be alright but I can't tell on the internet.

The cooker circuit is 40amp MCB therefore max amps for 6mm cable is 41amps

It is 47A - but yes.

therefore providing the Spark originally installed the correct MCB it must be 6mm cable and not 4mm as I originally thought?

Could be.

I was also thinking of wiring from the back of the new oven to the cooker plate with 6mm (as with spurs you have to use the same size cable as the original circuit)

No you don't have to use the same size but, as above re: the protection.

but 6mm can apparently be too thick for a non-static environment I. E moving oven out and in and can fracture the cable? Would it be OK to use 4mm from the back of the oven to the cooker plate I would think not?

Well, strictly speaking, it should be heat-resistant flexible cable but there are millions with T&E and no problems.

 

[EFLImpudence]

Basec 080 BS 6004 6242 Y H 2 x 6 (or maybe a 5??) + 2.5 SOMM PX 93
I don't think they do 5mm cable therefore must be a 6mm?

There you go. 6 and all's well.

Also found this inside the drywall...... Picture below, looks like they run short and extended with a terminal block....

Which cable is that?

 

[ScubaCollie]

Hi mate it's the cable leading to the double plug socket for the oven, I took the drywall backbox out of the wall to pull the cable through to check the size and I found that terminal block in the wall. Therefore I'm thinking of using a Wago terminal block and termination box to make it more secure?

 

[ScubaCollie]

Edit Ive just checked the continuity and that terminal block isn't feeding the oven must be kitchen circuit sockets..... Will check further tonight.

 

[ScubaCollie]

Hi All I've just purchased some 6mm heat resistant flexible cable HO7RNF.

Whilst in the wholesalers I got speaking to an electrician and when I said it has a 40amp MCB on the 6mm oven circuit he said it should be 32amp as they changed the regs about 8 years ago as it could catch fire?

Do I therefore now need to replace the MCB from 40 to 32amp?

 

[EFLImpudence]

No, that advice is rubbish.

 

[EFLImpudence]

Edit Ive just checked the continuity and that terminal block isn't feeding the oven must be kitchen circuit sockets..... Will check further tonight.

If those cables will reach the back box and you fit the dual backbox which allows two single gang accessories, then you could fit the Cooker Outlet and -

either join the cables in the backbox and fit a blank plate, OR -

if it is the socket circuit, fit a socket which you do not have to use.