Advise me.. Adding radial circuit for oven

Hi, I found this forum while searching for information about wiring up an electric oven. I realise I haven't searched the forum properly for my answers and I know that the golden rule is to search before asking, but I'm hoping to do this tonight so I thought I would post my plans and questions and hopefully get some feedback as I carry on searching...

I am fitting a 3450w/11,4kw oven (give or take a little bit,) with a gas hob.
With the existing oven being gas only I realise i have to fit a suitable radial circuit. Today I bought 6mm twin core +earth, a 45a control unit (with socket) and a terminal outlet box. I think all that is fine.

I had intended to buy a 40a mcb today (as thats what seems to be suggested) until the guy at the shop told me I had an older style consumer board and that it would cost me circa £30. I have a spare 45a mcb in the CU just now that would have originally been for a cooker.

Q1. Can I just use the existing 45a mcb and what are the effect of using an MCB with an overly high rating for the purpose. Is it correct to say there's a 10% margin that you can go either way.

Q2. I'm just away to investigate this more but I hadn't considered RCD/Earth leakage but read a post which suggests that where possible this should be considered with control units which have a Socket. Any input on this would be great

Q3. How can I figure out if i can run a kettle from that plug, Is it just a case of adding the ratings and ensuring it falls within the limits.

That's it for now. I hope I've provided enough information for some advice. I'm quite competent and safety conscious (with electric anyway) in terms of switching off etc and triple checking everything. I just need confidence that the hardware I'm using is suitable.

PS. The consumer board is a metal case, It has two rows of MCB's, A master switch and an RCD reset switch. The MCB's are MEM M6 Type 2's which, as i type this, I found out are Memshield. The CU is probably the same manufacturer but I am not home right now to check.

Thanks for any advice

G

Not qualified enough to provide technical input, but as the work is in a kitchen under Part P it is notifiable - which if you are not using a certified electician should be done prior to starting work.

I'm only putting the wiring in place, as i don't fancy poking about the consumer unit. Just trying to save labour costs. Am I safe enough to run the cables under the floor wire up the control unit, terminal outlet etc and have my spark just do the final Consumer unit wiring done and inspection of my handy work?

Actually just seen your location and Scotland manages to escape Part P IIRC so you can ignore my previous comment.

As for sparks signing off your cabling, you need to ask them. It would be false economy if you do the work and then can't get anybody to sign it off later.

leon1p said:

I am fitting a 3450w/11,4kw oven (give or take a little bit,) with a gas hob.

Click to expand...

IF your oven is 3450 watts, you need a 16 amp radial circuit in 2.5mm² twin and earth cable, with a 20 amp Double Pole switch for local isolation.

IF your oven is 11400 watts (where did you get the 2 figures from???), you need a 50 amp radial circuit run in 10mm² twin and earth, with a 50 amp local isolator.

There are no questions about either of these statements, though no domestic oven I have ever seen is 11.4kw.

Dont fit a control unit with a socket (though neither arrangement above will allow you to), as then the circuit will probably need to be on an RCD, and ovens dont like RCDs (and vice-versa). (see bottom of post)

The hob will probably require an electrical connection. Provide a socket spur from the ring main, via another 20 amp Double Pole switch above the worktop for easy isolation.

RCD protection must be afforded to all sockets that could be reasonably expected to provide power outdoors. With this wide a scope, it is best to protect all sockets on the ground floor.

Taking diversity into consideration, current demand would be 23.34A.
Therefore 40A MCB well in excess but doesn't mean you can't use it.

Had you bought a Cooker Control Unit without the socket, then your cooker could have been connected to the non-RCD side of your CU, which would have been better for you as RCDs have a habit of tripping. Not what you want when your Sunday roast is in the oven.

Your kitchen ring/radial could have been used to supply your sockets, as they should be protected.

It would have been better for you to have gone through all this with your electrician beforehand, rather than trying to find one willing to sign off the work afterwards.

Crafty
I took those numbers straight from the same data label. I will have another look at it now that all the numbers are starting to make sense, and post back.

luminaire
It's all a bit spur of the moment, none of this is planned. I only bought the oven yesterday (Im a mug for brushed steel).

I think I'll have to slow myself down until I get someone in. Thank you both for your advice so far though.

@ luminaire, the OP states the appliance is an oven with a gas hob. So unlikely to be 11+kw.

Hi,

I am doing something similar, I have a Kenwood CK404 cooker, its dual fuel, 5 gas hobs, and two ovens (electric). The sticker states this a 11kw oven.
Hope this helps