Replacing cooker

[wcavanagh]

Hi all,

Existing cooker is fed by 6mm through un insulated ceiling void, then down behind plaster. Approx run no more than 15m.

Replacing cooker with built in over and sep hob.

Oven says 13A
Induction Hob says 16A

Will this be ok on the 6mm cable or do I need to get a spark in to run in 10mm?

Cheers,
Will

 

[ban-all-sheds]

It'll be OK, assuming that it currently is.

But that's not your real problem.

Oven says 13A
Induction Hob says 16A

The cooker circuit is, probably, 30/32A?

The oven you can plug in, if you have a socket, but the hob?

Will this be ok on the 6mm cable or do I need to get a spark in to run in 10mm?

You'll need one to provide a socket or FCU for the oven, maybe.

And to provide you with a 16A protected supply for the hob if that's what the maker's installation instructions say...

 

[wcavanagh]

Thank you,
Yes the oven is on a 32 A MCU

The cooker outlet has a socket also,
So I could put a plug on the cooker no issues.
If the hob was wired in then I guess that will be wrong due to the 32A, all the hob says is 16A single phase, or 16A 2 phase.

Guess I need someone in to do something?

It is all tiled so keen to have min disruption.

 

[riveralt]

Hi all,
Existing cooker is fed by 6mm through un insulated ceiling void, then down behind plaster. Approx run no more than 15m.
Replacing cooker with built in over and sep hob.
Oven says 13A
Induction Hob says 16A
Will this be ok on the 6mm cable or do I need to get a spark in to run in 10mm?
Cheers,
Will

6mm will be okay. Check what the size of the MCB is and also is the circuit additionally protected by an RCD? A 32Amp MCB should be okay.

The manufacturers instructions should be followed regarding the method of connection to the mains - they sometimes insist that the circuit should be RCD protected as well.
I doubt that the 13Amp Oven will connected via a plug top and the MI will be probably say it should be permanently wired.

I assume the 6mm cable comes into a 45Amp Cooker switch at the moment and from there to a cooker connection unit.

Assuming both oven and hob require hard wiring I would replace the cooker connection with a dual one like this.
http://www.alertelectrical.com/prod/1022/click-45a-easyfit-dual-appliance-outlet-plate
This will allow you to connect both your oven and hob to one unit.
The purpose of the MCB is to protect the cable - so check that the cable that comes with the hob and oven is 4mm or higher.
If the oven can be wired via a plug top then run a 4mm cable between the cooker connection unit and an additional socket.

 

[wcavanagh]

Thank you very much,
Both the hob and oven are pre wired with heat proof flex. Looks about 4mm

Cheers,
Will

 

[sparkwright]

Thank you very much,
Both the hob and oven are pre wired with heat proof flex. Looks about 4mm

Cheers,
Will

Is it though?

Why would appliances rated at 13 or 16 amp have cable rated around 30 amp?

What is your basis for saying the cable 'looks about 4 mm'?

 

[wcavanagh]

Just had a closer look, took them out the boxes.

The flex on the oven is 2.5mm as I compared it to some 2.5mm twin and earth, ithe flex is only slightly thicker, guess because it is stranded, I'm looking at each cable not the flex dia.

Same goes for hob, BUT it has two cables crimped together for the live and neutral, but all of them are about 2.5mm

Manuals make no reference to connection, oven says if conned to plug, fit a 13a fuse, that's the only clue.

Hob says nothing other than 16a supply

 

[riveralt]

I was under the impression, in the uk, that any piece of electrical equipment that was to be connected via a 13amp plug top should come with one fitted.
If one is not fitted then it may require to the permanently fitted.

As I said the MCB is there to protect the cable - when clipped direct 2.5mm cable is rated at 27Amps. Whereas 4mm in the same circumstances is rated at 37Amps.

Personally I would speak to the manufacturers firstly to ascertain what is the actual cable size and secondly to establish how they want the oven and hob to be connected to the mains supply.

If it is 2.5mm then you may have to change the MCB for that circuit down to 16 or 20Amp and find another way to connect your oven to the power supply.
Alternatively you could increase the size of the cable to 4mm and leave the MCB as it is. Though that may affect your warranty.

 

[wcavanagh]

Cheers all,
What a pain, I think the oven is easy enough and will put this on a 13a FCU, can change the cooker socked to a split one easy enough.

The hob, dam 16a what an odd figure, will give the Manu a call and see what they expect.

 

[wcavanagh]

Just downloaded the hob manual from Manu website.

Hob needs a min of 30a omnipolar circuit breaker with 3mm gap.

That changes things then.

Looks like use old 6mm cable with 32a breaker to supply hob only.

Then sep supply to 13a FCU for oven.

What a pain

 

[sparkwright]

One (slightly expensive and time consuming) option would be to fit a 2 way consumer unit on the end of the 6 mm cable in a nearby cupboard.

Fit two 16 amp MCBs. One 16 amp MCB can do the hob, via a 20 amp double pole switch, in 2.5 mm cable.
The other 16 amp MCB can do the oven, via a 13 amp switched fused spur or a 13 amp socket, in 2.5 mm cable.

This way you will not have to alter the main 32 amp cooker MCB. The cooker switch can stay as it is. You won't have to replace the flexes already fitted on the appliances. The appliance flexes and all internal wiring will be correctly protected at 13 and 16 amp which may be required in the instructions.

 

[JohnW2]

I was under the impression, in the uk, that any piece of electrical equipment that was to be connected via a 13amp plug top should come with one fitted.

Give or take the 'top' ( ), I'm sure that is true of electrical equipment which definitely needs to be plugged into a socket - is the requirement perhaps relaxed when (as could be the case with ovens) there is an option to fit a plug or hard-wire the equipment? I certaintly don't know if that is the case, but maybe someone does?

Whatever, as you say, the OP should be guided by what the manufacturer says about the elctricity supply for the equipment.

Kind Regards, John.