Please help-Wiring Advice for a Rangemaster Induction Cooker

[TonyChapple]

Im sure the best advice will be to get a sparky in - but I just wanted to see if anyone could give some useful advice before I part with LOTS of money !!

I have just purchased a rangemaster Induction cooker and I think I might have made a mistake !

The orignal cooker (Stoves dual fuel) is on a seperate wiring circuit back to an RCD at the cu (I believe its fused at the CU @ 32 amps?)

The wiring looks like its 6mm not 10 mm.
My question is will 6 mm be enough for the new induction cooker ?

Looking at the installation manual it says maximum power consumption is - wait for it - 17.1 kilowatts !!!

Seems a massive amount to me - but 5 rings add up to just over 9 kilowatts, plus to electric ovens and a grill - maybe its right !

The cu is in the hallway about 15 meters from kitchen - replacing the cable to the cu is going to be a NIGHTMARE taking floorboards up and going under concrete floor (kitchen in extension) etc. etc.

If you need more info to help advice - just ask and I'll try and answer.

Many thanks for your help - it will be MUCH appreciated.

Tony

 

[EdwardCurrent]

Is this a 'domestic' installation ?
Provided your isolator does not incorporate a socket outlet, allowing for max demand and diversity 6mm would be ok @ 29A. Wait for other replies for confirmation.
Ed

 

[PrenticeBoyofDerry]

My calc get you under 32amps, using diversity and the cable size should be okay, providing the route the cable is taking, does not mean other factors such as cable bunching and thermal insulation need to be applied.
If a socket outlet is on the cooker control unit you would be over the accepted current rating.

 

[ban-all-sheds]

I have just purchased a rangemaster Induction cooker and I think I might have made a mistake !

You had a dual fuel cooker, which means you have a gas supply there.

IMO the biggest mistake you made was not sticking with gas for the hob, but there ya go.

My question is will 6 mm be enough for the new induction cooker ?

The question really is will 32A be enough?

Looking at the installation manual it says maximum power consumption is - wait for it - 17.1 kilowatts !!!

Seems a massive amount to me - but 5 rings add up to just over 9 kilowatts, plus to electric ovens and a grill - maybe its right !

Cooker circuits are traditionally designed using diversity. Basically the assumption is that you don't have all the rings, ovens and grills running flat out all of the time.

The guidance is that that only applies to cookers up to 15kW, probably because traditionally people didn't have large cookers in their homes, so big ones implied commercial use where usage patterns were different.

But ignoring that, your 17.1kW cooker comes out at 29A, or 34A if there's a socket on the cooker switch. (Assuming 17.1kW is at 230V. If it's at 240V then the figures are 28A/33A.)

So you're on the edge, particularly as I believe that some induction hobs have a boost facility which upsets the diversity assumptions.

The cu is in the hallway about 15 meters from kitchen - replacing the cable to the cu is going to be a NIGHTMARE taking floorboards up and going under concrete floor (kitchen in extension) etc. etc.

Using the existing circuit should not be dangerous - the 32A breaker protects the cable, but if it isn't large enough the breaker will keep tripping.

However, if you are determined to stick with the cooker, or now have no choice but to stick with it, then why not suck it and see? If you do find that the breaker trips then you will have no choice but to bite the bullet and put in a new circuit. Try simulating a major event - big dinner party, Xmas lunch etc, so that you'll know, rather than finding out for real that it can't cope.

 

[LiamPope]

My dual fuel Rangemaster is just over 7kW and that's just the ovens and grill. If it had a double width induction hob sitting on top, I guess 17.1kW would be about right!

As above, if you apply the maximum diversity, and make sure there is no 13A socket on the cooker switch, your existing 6mm 32A circuit just about passes. Whether you can apply diversity to an induction hob is a bit of a grey area. What do the instructions say regarding the power supply requirements? Even if you can, whether you should apply diversity to a cooker circuit is also worth considering. I chose to apply none at all to my cooker circuit design as I know the cooker will regularly be used to full capacity and I wanted the circuit suitably rated to avoid nuissance tripping and also to allow future expansion.

As BAS says (assuming your existing circuit was designed properly in the first place) the worst you will experience is the circuit tripping if you use all those 17kW for too long (christmas day for example!). You may be able to mitigate this by swapping the 32A protective device for a 40A (or even 45A) one as the existing 6mm cable could be rated up to 47A. You would have to be absolutely sure of the route the cable takes - that it isn't bunched with other cables or in any insulation throughout its entire length. 40A ought to do, and that even gives you some breathing space to apply a 40 degree ambient temp derating factor if the cable goes through a loft that gets hot. This is all assuming a 40A device is available for your CU. Swapping the protective device is notifiable work so you'd want to get a spark involved or you'll have to pay building control fees.

Even if you were going to just suck it and see with the existing circuit, you'd still be well advised to consider/inspect the cable run, as it is possible that the existing cable isn't even suitable for 32A depending on how it is installed. This might not have caused a problem with your old cooker with its lower demand, but if you are about to use this circuit to it's full capacity with the new cooker you could have a potentially fire-causing situation if indeed factors are in play that make the existing cable unsuitable.

 

[TonyChapple]

VERY much for your thoughts.

A few points - yes it is a domestic installation.

The cables ARE bunched together (cable tied) at the point they go into the CU. The cables come up from under the floor - but trying to track thier route will be a nightmare ! (Theres wooden laminate flooring over floorboards in the hall - then a concrete floor in the kitchen with a flat roof extension - I dont know how the cables go from the hall into the kitchen - might be in flat roof - might be in floor for all I know).
So it sounds to me that using the existing 6 mm cable is 'risky' at best ?

So - if everyone agrees, its back to square 1 and re install the cooker ring

Any suggestions how best to do this ? Or is that a silly question !!

Thanks again everyone.

Tony
This is going to cost more than the cooker !!!!!! help !!!!

 

[TonyChapple]

..... I better get in there and say "Its time to get a sparky in" before someone else does !!

If it was a case of woring in the new cooker to an existing ring - I could do that - but replacing 6mm from the CU to the cooker I guess is a job for the professionals !!

Many thanks for your help

Tony

 

[LoveRocket]

Sigh.

Have you actually read what anyone's said to you?

6mm cable on a 32amp OPD is fine. The only 'risk' is that the breaker trips if you're wanging the cooker full blast. - it's not going to burn your house down. But you seem to want to rip your house apart and shell out £££ on spark, so crack on mate.

Oh, and cooker circuits are certainly not "rings".

Although it's very rare of me to do so, I completely agree with Banal; if you've got gas then bloody use it - it's much better for cooking, and a lot cheaper to run.

PS. Did you consider the electrical requirements before you bought this cooker?

 

[TonyChapple]

if you are about to use this circuit to it's full capacity with the new cooker you could have a potentially fire-causing situation if indeed factors are in play that make the existing cable unsuitable.

<sigh right back at you>

Actually yes I did read what was being said. Thanks mate.
As I cant check the "ring" opps, sorry, "circuit" (how dare I get my terminology wrong) to see if its bunched with other cables etc. as per the helpful reply from Liam, it seems risky to me. Cant see any insurance company being helpful if a fire is caused because I've wired in a cooker into a circuit thats not capable of supporting the increased power consumption.

 

[LiamPope]

Sigh.

Have you actually read what anyone's said to you?

6mm cable on a 32amp OPD is fine.

Sigh.

Have you read what I wrote?

You can assure the OP that the existing cable is suitable, can you? You can see that no combination of insulation and/or bunching exists that means it actually isn't? He's 100% OK to add an extra 10kW of cooking appliance to that circuit?

I admit it's likely it will be fine (although he has said it may go through a flat roof which may well have >100mm insulation in it), but if I was about to increase the demand so significantly on an existing circuit, I'd want to be sure it was properly rated in the first place, wouldn't you? That's why I said the OP would be well advised to consider/inspect the cable routing even if he's using the existing circuit. Would you disagree with that advice?

OP, you most likely can use the existing circuit as is. Even if it nuissance trips, the simple option of swapping the protective device for a 40A version could exist. If you can't confirm the suitability of the existing cable a new circuit may be the best option. Obviously I haven't seen the property, but you might be surprised how little mess can be made by a spark fishing cables where the sun doesn't shine, and I'd be surprised if installing a new circuit could cost anywhere near what that new Rangemaster cost.

 

[Alexiey]

Hello,
I have been reading all the replies with great interest and I was surprised to see what some people had to say.

The bottom line is I have just bought a RangeMaster Classic Induction Delux ALL ELECTRIC and the advice I got from the seller was to wire in using a 10mm cable protected with a 45A RCD breaker in your consumer unit.

I had 6mm + a 30A breaker with my old style Oven and Hob and that was fine.
No way should you connect this style of cooker into a 240 ring main socket it has to be wired on its own circuit just like an electric shower.

6mm cable and a 32A breaker may be ok BUT if you want the whole thing to be singing and dancing, eg Christmas you dont want the inconvenience of a breaker tripping and perhaps your cable overheating and causing a massive overload - fire expense need I go on!!!!!!!!!

As one writer suggested if YOU dont know get a PROFESSIONAL who does not a mate from the pub who thinks he knows!!!!! Better safe and a few pounds spent just now than have to pay a massive outlay due to incorrect set up
Good Luck

 

[Taylortwocities]

EDIT: Mostly........

 

[ban-all-sheds]

...your cable overheating and causing a massive overload - fire expense need I go on!!!!!!!!!

No, you certainly do not need to go on about a cable complying with Ib &#8804; In &#8804; Iz overheating and catching fire.