Cooker connection confusions.

[Chipster-GT4]

Afternoon,

I have what I think is a small issue with replacing my current Gas Cooker with electric oven & hob & hood.

The cooker has a wired 13amp plug and the Hob is 6800w.

My issue is that I have a Cooker Switch and 13amp socket next where the cooker is located. So my plan was to connect the Hob to the Cooker circuit and the oven to a spur from the Downstairs ring main. But what should I do for power for the hood.

My only option is to extend the ringmain to add a new socket for the cooker and then take a spur from this to feed the hood

My other slight concern is that the CU seems to only have a 20amp fuse for the cooker circuit and its an old style brown Wylex unit with 6 fuse connections (which are all in use)

1 x 5amp (white) - All Lights
2 x 30amp (red) - Up / Down Ring Main
2 x 15amp (Blue) - Warm air heating / Water heater
1 x 20amp (Yellow) - Cooker..

Any thoughts / suggests gratefully received.

Cheers

Paul

 

[didthathurt]

I think you will need to undertake more work than your post suggests you are anticipating for this job. The oven you describe has a peak load requirement of 30 Amps and is not suitable for spurring from a ring main. You are only allowed to connect an oven into a ring main if it is rated at 13Amps or less (3kW max in practise). For your oven you would need a cable rated to 41Amps (assuming you CU has rewirable fuses which, from your description, it probably has). That is a 6mm cable at a minimum, fused to 30Amps. Your current CU is not up to this addition as it does not have a sufficiently high current rating.

This thread
//www.diynot.com/forums/viewtopic.php?t=62233
deals with the CU issue in quite a bit of depth.

To do what you propose, therefore, you will need at least a new Consumer Unit, a rewired cooker supply circuit using at least 6sq mm cable (I'd use 10mm cable as it will future proof against the chance of a full scale range cooker being installed in the future) and the hood will be spurrable as will the hob.

That is as a bare minimum. Given the consumer unit you have though, unless your house has been rewired in the not too distant past, I would most seriously recommend you get the condition of the whole wiring system professionally assessed. Rewires aren't cheap, but they're a lot cheaper than some of the possible alternatives!

Also, don't forget that kitchen work is Part P notifiable (for the reasons the above answer is at some length).

 

[JohnD]

You might also consider a dual-fuel cooker with a gas hob and an electric oven.

These are actually better to cook with, and usually only need a 13Amp plug for the oven.

 

[Chipster-GT4]

JohnD - The applicances have already been purchase (mistake) I didn't realise the current draw of an electric hob

DidthatHurt - The more I have read the more I though I'd need to replace the CU. The Oven itself is rated below 3kW so that would be ok on the ring main (although better on it's own ring) I'd worked out the 6.8Kw load was just under 30amp (must have got my calcs wrong).

If the existing Cooker circuit has the correct cable I assume (from reading the link) that the CU would possibly not support the load requirements.

Thanks for your replies.. I think I might be calling a professional !

 

[JohnD]

... an old style brown Wylex....

Might be best.

 

[Chipster-GT4]

But if it was just the Hob 6.8Kw connected to the "Cooker" circuit what should the Cable size and fuse rating be ?

Cheers

 

[JohnD]

As didthathurt said earlier -

6.8kw divided by (nominal) 220v is 30.9 Amps. So a 32A MCB. (because of the way cookers work, it is unlikely that it would ever use max power for more than a few minutes at a time, and that would be when you had everything on to cook a big meal, e.g. Christmas dinner).

Cable could be 6mm sq min but 10mm would be better, as the installation effort is the same and it gives capacity for a larger all-electric cooker if you or someone else decides to get one later.

The Brown Wylex is between 35 and 50 years old, and it's time you got a new one. The rest of your installation is almost certainly the same age, hence didthathurt's advice.

BTW beware of the words "Oven" and "Cooker" used interchangeably - they are not the same thing.

 

[Chipster-GT4]

I think it is most certainly time to upgrade the CU...

My other issue is the single lighting circuit, have totalled up the bulb wattage around the house it looks I make 1100w already and thats before any new lights go in...

Thanks for all the help