New Oven and Hob

[atcfan]

Hello,

I would like to get some advice on fitting a new oven and hob.

Current install (not mine):

Oven. On its own circuit, 40A MCB, 6mm T&E to 45A cooker switch/socket, 6mm T&E to oven (no connector plate)

Hob. Plugged into a 13A socket mounted in a cupboard next to the oven!!!

The new oven is 3Kw and hob 6.5Kw. I would like to have them both on the same circuit, i.e. move the hob over to the ovens circuit. I’m thinking of connecting the 6mm T&E from the switch to a Click PRW217 dual outlet plate, but not sure which size cables to use form there.

Both the oven and hob have come supplied with 2.5mm flex cables, but no plugs.

Installation instructions for the oven have also got me confused. Use a 16A fuse?

Why 16A and not 13 (3000W/230V = 13A) ??

So I would appreciate any advice on connecting the oven and hob. I’m assuming the 2.5mm flexes are a no go because of the 40A MCB and that there’s no such thing as a 16A fused spur. Also, are there any regs regarding positioning of the outlet plate?

Many thanks.

 

[terryplumb]

You can connect both to a dual outlet plate. 3kw appliances on their own dedicated circuit are preferred ,rather than connecting them to a ring final circuit which has other loads on it.
The 16 amp fused spur can be ignored ,it's nonsense.

 

[Taylortwocities]

@atcfan firstly, the instructions are wrong. There is no such thing (in the Uk) as a 16AMP fused spur.
Leave the circuit as it is. Fit a dual appliance plate. Wire both oven and hob to the plate. Done.

 

[mcprinter]

Used one of these dual outlets recently for the same sort of job

45 Amp Dual Appliance/Cooker Outlet Plate | Scolmore (PRW217)

Back box is a separate item

35mm Surface box (for AA 45DCOP) | Scolmore (PRW218)

Got mine from Amazon
Cost a little more but convenient.

 

[atcfan]

Thanks for the replies.

Could someone advise on cable size. I'm not sure about the 2.5 flexes because of the 40A MCB.

Used one of these dual outlets recently for the same sort of job

45 Amp Dual Appliance/Cooker Outlet Plate | Scolmore (PRW217)

Back box is a separate item

35mm Surface box (for AA 45DCOP) | Scolmore (PRW218)

Got mine from Amazon
Cost a little more but convenient.

Hi, did you buy the back box as well? If so, how did you get the cable into the box. The way I see it I have two choices, dig out a small channel in the wall to go through the rear knockout or go in through the top of the box, not ideal!

 

[Jon c]

The MCB is there to protect the circuit cable (your 6mm t&e) not the appliance, the 2.5 flex on the oven and hob can be considered part of the appliance since it is pre installed by the manufacturer. They are also fixed loads, so cannot pull anymore power than their rating. Any fault on the 2.5 flex the 40A mcb will trip just fine anyway. Oven and hob instructions are often translated from European countries that have vastly different requirements for electrical installations, the manufacturers aren't normally aware of the standard hob/oven circuits and accessories used in the UK so the instructions are often plain wrong.

 

[terryplumb]

Thanks for the replies.

Could someone advise on cable size. I'm not sure about the 2.5 flexes because of the 40A MCB

The MCB protects the circuit cable ,it's nowt to do with the appliance or the flex that comes with them.
Use the mounting box knock outs for cable entry,that's what they are for.

 

[atcfan]

I'm not worried about the appliances, I know the MCB is there to protect the cable not the appliance but I didn't know the cable was considered part of the appliance, thanks for the info. My school of thought was 'shouldn't the cable have a rating equal to or greater than the MCB'.


Regarding the mounting back box, the only knockout I can see from the photos (haven't bought one yet) is at the rear of the box, which will be mounted on the wall.

 

[mcprinter]

Thanks for the replies.

Could someone advise on cable size. I'm not sure about the 2.5 flexes because of the 40A MCB.



Hi, did you buy the back box as well? If so, how did you get the cable into the box. The way I see it I have two choices, dig out a small channel in the wall to go through the rear knockout or go in through the top of the box, not ideal!

I did buy the back box
Cable from the cooker switch is buried in the wall so I fed into the rear rectangular knockout.

 

[Jon c]

I'm not worried about the appliances, I know the MCB is there to protect the cable not the appliance but I didn't know the cable was considered part of the appliance, thanks for the info. My school of thought was 'shouldn't the cable have a rating equal to or greater than the MCB'.


Regarding the mounting back box, the only knockout I can see from the photos (haven't bought one yet) is at the rear of the box, which will be mounted on the wall.

That's definitely a sensible thought, and if you were installing a flex for the hob yourself you may well go for something larger than 2.5, but the flex the manufacturer installs is rated for the maximum power draw of the appliance, now I know 6.5kw is just over the rating for 2.5mm flex, however it will take diversity into account which basically says the hob won't draw full power all the time due to thermostats switching on and off. So the fact that the flex cannot be overloaded since it supplies a fixed maximum load means it is fine to connect to an MCB of higher rating. If there was a fault within the flex itself you would find the MCB would still disconnect within the required time, since it is so short. A Zs test at the end of the flex would confirm this, assuming the rest of the circuit is healthy it would never be a problem. Another thing to consider is the internal wiring inside the appliances, I have taken a few ovens apart and the wiring inside is definitely not rated anywhere near 40A or even 32A, and it normally isn't internally fused. This again comes down to it being a fixed load, so overload just isn't possible, and again a short circuit would still disconnect in time. Manufacturers cannot rely on the circuit protection for the appliance, if anything needs fuse protecting they would need to install an internal fuse. Its good that you're thinking about it though!

The click dual outlet plate has two cable clamps for the appliance flexes on the front plate, the cover for it has two knockouts you will need to remove to allow the flex to exit without getting crushed