installing sparky insists installation is safe and correct, 3 others under rate the cable

[arnold123]

Hi all, I'm having a terrible time after having building work done. The electric cable to my new hob was quoted and agreed 10mm, it's a neff 10100w induction, 43 amps. The electrics were subbed by the builder. The junior electrician fitted a 6mm. Another electrician from the firm came to power up and refused saying the cable was too small. It's approx 5/6m to fuse board runs down a wall in plaster then enters small flex conduit under new tiled floor. Owner of electrical firm said the cable wasn't too small and it would be fine given it's installation method & applying diversity. Smelling a rat I had another sparky look at it and he said it's not big enough. I then had another sparky do a written report and he also said the cable is not adequate. The original installer maintains it's safe, I'm only using half of the hob under advice of 2nd spark. Today I rang ELECSA technical and based on what I told him he agrees it's not big enough besides the fact I was quoted for 10mm. I wondered what you guys thought as I've gained so much information reading posts on here.

 

[Wilko]

Hello and welcome to the forum.
Can you post the hob model number please?

 

[arnold123]

Hi Wilko, its a neff t54t97n2

 

[David Prosser]

If you have it in black and white that a 10mm cable should of been fitted then regardless of cable rating arguments you should have a 10mm cable.

Just out of interest is the new floor heated ?

How would he like it if you only paid 60% of the bill ?

 

[Dave OCD]

Is this cable purely supplying the hob or is there an oven as well ?

 

[Flanders]

What is the size of the fuse , circuit breaker fod this circuit

 

[arnold123]

The breaker is 40A and the supply is only for the hob. My thoughts exactly supply of services materials specified etc should be 10mm cable as quoted, also to future proof upgrading. Thing is they will never get a 10mm in that flex as 2 men pulled like hell to get the 6mm in alongside another cable that powers an extractor. Implications are tiles need to come up, so new 38m2 floor replacing as well as fitted kitchen being removed which has a stone work surface. Costs could will be thousands. Hopefully ELECSA will come and inspect.

 

[arnold123]

Floor is not heated.

 

[Octopus]

Well - if the quote says 10mm , get them, at their cost to change the cable .... and there is no way that that hob needs 10mm cable

We have a rangemaster cooker with induction hob, the spec says 17.7 KW - Rangemaster stipulate 6mm...... I fitted 10mm!

 

[arnold123]

Herein is the problem it's up to the electrician to come up with the design. He says it's ok, 3 others say it's not. Why did he quote for a 10mm if it only needed a 6mm ..... also can you really apply diversity to a single appliance if you intend to cook a lot and use all the flex zones?

 

[Dave OCD]

There will be many that say a 6mm cable is perfectly adequate and strictly speaking it probably would be, but they've been really stupid to ignore the quoted specification. Hopefully they can find a less disruptive way to resolve this.

 

[Rocboni]

Can it not be put in on a 32A MCB that way if you try to use to much then it will simply trip, how often are you likely to be using the whole job other than Christmas Day...

However if you have it in the quote for a 10mm then it should be a 10mm!

 

[Wilko]

I'm sorry to hear of your troubles. I'll put some thoughts down for folks to comment

With these installation methods a 40A circuit breaker should be ok to protect the cable (underfloor likely method 60 going to ref method B and 41A). The hob guide with electrical detail I found was not from Neff website (I must be blind, sorry), but it does state 10.8KW connected load and asks for a 45A circuit breaker (10,800/240=45, how about that?)

Neff T54T97N2 Black glass 5 zone induction hob available from Cameo Kitchens - http://www.cameokitchens.co.uk/product.php/12280/neff_t54t97n2

I think cookers never run full bore for more than a few minutes (food prep times with only one cook in a domestic kitchen and after temp has been achieved the draw is reduced). I think it's unlikely your hob would draw full current for more than a few minutes and so this arrangement should work fine. But that's just an opinion and others please comment. The actual current draw could be checked by your Electrician to confirm or other.

Anyway, it's not your contracted arrangement - which they should have honoured or negotiated out, in my view.

 

[Octopus]

Herein is the problem it's up to the electrician to come up with the design. He says it's ok, 3 others say it's not. Why did he quote for a 10mm if it only needed a 6mm ..... also can you really apply diversity to a single appliance if you intend to cook a lot and use all the flex zones?

Me thinks they need to get out more....

How about a call to Neff to clear this up once and for all?

 

[HandySparks]

Some induction hobs will regulate the power so that the maximum drawn from the supply is less than the total rated power of the elements. Mine limits to about 7kW despite having four elements that can be driven at up to 4kW each. Get one of the electricians to measure the actual current with a pan of cold water on each element and power turned up to max.

Incidentally, John Lewis list the max power for this hob as 7.2kW. Now maybe it's an error. Or maybe they actually know what they're selling.

 

[arnold123]

Tbh we cook a lot which is why we purchased this expensive hob. We cook as does my son @ daughter in law to be who live with us. ELECSA tech said that he is 99.9 certain that the 40A breaker will protect the circuit but the cable is not sufficient for full power and I should be able to use full power if I wish and it has power boost esp as I said we cook a lot. They have been stupid to ignore quoted spec and are trying to suggest installing a flex cable. They have also connected the new hob and not inspected the works or notified it since 1st November....

 

[Wilko]

Oops - wrong table, should be 4D2A which is 38A for B or 46A for C.

 

[kingeri]

My cooker pulls 32A when the four induction hobs are on full whack, and it still lets me turn both ovens on as well. Manufacturers instructions still state 6mm cable and 30/32A circuit though. And that is what it's sitting on. My wife bakes and cooks like mad and guess what? It's fine!

 

[arnold123]

So why are 3 sparks disputing the cable......Emailed Neff, they never responded! LABC just want a certificate from someone. How can you have electrical work done by a junior that could be unsafe and a cert promised by a supervisor that hasn't supervised. Is there a loophole here?

 

[arnold123]

The installer did offer to put a clamp meter on with all zones going but 2nd sparky said "that would only confirm what the manufacturer has rated the hob at" the cable is still under sized.