Induction cooker circuit wiring

SashikoStitcher

You’re probably right about the retailer getting its figures wrong @DullGreyGuy- I just looked on the Stoves website at the manual for that one I screen shotted and I see it doesn’t mention the fuse size at all, only the power rating. So wherever the retailer got that from, it was not Stoves. 

SashikoStitcher

Interesting development. Finally got through to Stoves, who told me that any of their induction Range cookers apart from the Zoneless one that I chose will be fine on 6mm/32A. They were categorical about it, no caveats about double checking with an electrician. 

So I can hopefully exchange for a different induction model. 

That said, I appreciate that an electrician will want to take his or her own view as they are the ones who sign off the circuit/installation. 

We have a guy coming round tomorrow to look at our setup. 

FreeBear

SashikoStitcher said:

Interesting development. Finally got through to Stoves, who told me that any of their induction Range cookers apart from the Zoneless one that I chose will be fine on 6mm/32A. They were categorical about it, no caveats about double checking with an electrician.

It is all about "diversity". Whilst a cooker may have a total peak consumption of 15kW (62.5A), accounting for diversity, current rating of the cable would be ~25.75A - Well within the limits of a 32A fuse/mcb. Cable sizing will still be dependent on length and type of wall.

For more information, see - https://www.tlc-direct.co.uk/Book/6.5.2.htm

Risteard

SashikoStitcher said:

This is just a warning to anyone thinking of getting an induction hob or range cooker. 

Our cooker circuit, which was installed 6 years ago as part of a kitchen refit, has 6mm cabling. I understand this is the standard size for most cooker circuits. Our dual fuel Rangemaster has been running on it no problem for years. 

I ordered a new induction-top Range (Stoves brand) but only discovered after delivery that it needs 10mm cabling to be connected. 

It’s not an easy job to replace the 6mm with 10mm as the 10mm is so thick it can’t just be pulled through the same channels. We’re looking at huge expense and disruption to do it, so the new cooker has to go back. 

The one I chose does have particularly high power rating but the retailer says that there are no inductions that work with 6mm. 

By the way, my electrician wanted to speak to Stoves customer service to discuss the spec but they are completely uncontactable- website says “speak to our friendly team” but we’ve been trying for 3 days and the line cuts off with “your call cannot be completed, please try later” after a recorded message.  They have no email and don’t reply to their online enquiry form.  

Plenty will be absolutely fine on 6mm^2 cable. My oven and induction hob share a standard cooker circuit.

Risteard

SashikoStitcher said:

PS In your opinion would anything rated 32A run on 6mm, or is it more complicated than that? 

I ask as I can see several induction ranges on my retailer’s website that say 32A, eg this one, which is a Stoves. 

Total connected load (TCL) is generally a red herring as often different parts can't be simultaneously energised (e.g. oven and grill). Also there will be thermostatic control.

FFHillbilly

6mm will probably be fine for any oven/hob combination in a house that is just used for cooking for a family. theres a calculation in the regulations (BS7671) called Diversity, it allows for the fact that it's physically impossible to use ovens and hobs to their maximum rated capacity for an amount of time thats going to make a difference.
if anyone has ever opened up an oven or a hob they will find tiny wires connecting the elements to the main supply that are NOT sized according to BS7671, but they work fine...
similarly, almost every house in the country with a 100A main fuse has a supply cable thats is undersized for 100A, but houses are not using 100A all day long so it doesn't matter
Manufacturers instructions don't help either, a lot are written by someone with no idea what they are talking about, or they have been translated from Chinese badly. they are also written for the worldwide market so don't take local limitations into consideration, IMO the use of 10mm or 16mm cable in a domestic cooker circuit is probably more likely to cause a problem than it is going to make it safe, 10mm is difficult to terminate, 16mm is almost impossible to terminate into the small switches and backboxes used in a house, the cable is so stiff any movement loosens the joint and eventually it'll burn out