Induction hob mixed opinion.

[wade88]

Hi guys,

Im getting some mixed opinion about how i should go about wiring in a new induction hob and cooker.

The current cooker is going to be moved above the work surface and built into the kitchen furniture about 4 ft from the floor while the induction hob is going to be fitted into the work surface. now the current cooker has its own existing supply...fine, 45 breaker, 45 switch etc.

I was planning on simply putting both appliances on different circuits, with their own switches, as this seemed like the far safer and more sensible thing to do, as i dont belive the one 45amp cooker switch will suffice if a sunday roast is being cooked for exmaple and all 4-5 hob rings are on and the cooker is going full whack trying to cook up the bird. but i have been told that putting both on the same switch is acceptable.

Initial figures when designing this install tell me this would be a pants idea.

 

[malcolmsanford]

Without you telling us any load specs hard really to comment.

Have a look at pg 160 of the OSG section 8.4

Good for any type of cooker.oven even induction.

 

[wade88]

No i understand that i was just fishing for opinion as usual as i drink my coffee.

 

[malcolmsanford]

Well I think the 2 seperate circuits would be the best design as if there was a fault on one appliance it could be isolated and the use of the other still available. Also you are complying with Regulations 314.

What the 2 appliances on a single switch will give you are many get outs. You may not be able to run an extra circuit for many reasons. No extra space in a CU, the client does not want the unheaveal. Space for fitting another CCU or switch in the kitchen.

So like all design work, you as the designer will have to decide in the circumstances what is the best install for this job.

 

[Notsosmart]

IMHO always good practice to install a new circuit to separate the oven from the hob, this was proven after being called out to a new kitchen installation which kept tripping the (single) breaker when three of the four rings and the oven were being used at the same time. So requiring a new circuit to be installed and the destruction of some of the brand new tiles! (Luckily some spare to hand so no real harm done)

Obviously max demand then needs to be taken into account as diversity for ovens only includes attached hobs.

 

[malcolmsanford]

IMHO always good practice to install a new circuit to separate the oven from the hob, this was proven after being called out to a new kitchen installation which kept tripping the (single) breaker when three of the four rings and the oven were being used at the same time. So requiring a new circuit to be installed and the destruction of some of the brand new tiles! (Luckily some spare to hand so no real harm done)

Obviously max demand then needs to be taken into account as diversity for ovens only includes attached hobs.

Sorry is that saying that seperate hobs have no diversity??

 

[pushrod]

Well i am going to disagree with Malcolm and Notsosmart and say that i would present the options to the client and say that if the 45A breaker is correctly installed there is more than enough CCC for most ovens and hobs on the same circuit. They might well decide to go with 2 separate circuits for the possible convenience. They also may well greatly appreciate you thinking of their financial saving which might in turn lead to more work from them and word of mouth recommendations. Also if you haven't mentioned the possibility that both can go on the existing circuit, if another spark quotes for this it would show you in a bad light and could lead them to doubting your integrity.

 

[Engineer54]

The cooker supply senerio again.... lol!!

Any combination of cooker load to 15KW you can use the BRB diversity formula with complete peace of mind, it's been working for getting on 60 years!!! Bigger loads can be adjusted accordingly. I've stated this so many times now, but here goes again, ...Oven elements, you may have 3 such elements in a typical oven, but they can not be utilised at the same time. there is normally say a circular fan oven element, a traditional normal oven element, and a grill element. You can however often use the fan without the fan element with the normal oven element. These dammed manufacturers still seem to quote max connected loads, and not max ''operating'' loads, which causes a lot of unfounded concerns...

Hob elements no matter what type, are going to be switching off and on thermostatically during the cooking period, so at times yes they could all be on a the same time. How long they will be all on is another matter, certainly not long enough, to bring the protection device to anywhere near it's operating limit.
I have a 8KW induction hob, and a 1 1/2 oven here. Supplied by 6mm cables (my house installation is all PVC conduit and singles) and a 32A MCB, and we have never had a problem, even at peak times when we have had several guests for dinner etc!!!

 

[pushrod]

. I've stated this so many times now, but here goes again, ...QUOTE]

Think you'll probs get to say it quite a few times more as well - seems to be a secret

 

[wade88]

Thanks chaps,

good feedback, i much appreciate it. Sorry to dig up old dirt...again

 

[wade88]

Well unless I misread it sounds like you haven't got a suitable supply for your new hob, you need a dedicated circuit large enough for the hob. The oven can be connected to the existing socket assuming it has a plug.

Diversity is applied over a wide area not a single device ... e.g. if you plugged a 13 amp fan heater into every socket in your house you'd expect fuses to start blowing but diversity says its unreasonable to expect every socket to be supplying its maximum rated current. You shouldn't really apply it to a hob because its very likely there will be occasions when all the rings will be on high (christmas anyone?). Induction hobs are worse because the way they operate at low power settings is to pulse the full power on and off briefly.

In short, no, you need a dedicated supply for the hob.


Read more: Diversity: Having elec oven AND Induction hob from cooker sw - DIYnot.com - DIY and Home Improvement​

That was an opinion given on DIYnot forum, and appears to be a common one. hence my confusion. All the posts on that forum appear adamant that a new circuit is required for induction hobs.

 

[malcolmsanford]

Well each to their own ....................I suggest Wade you glean what ever result you feel is best for you.

 

[wade88]

Well its whatever is best for the customer really isnt it so i shall present options and work accordingly.

 

[malcolmsanford]

Induction hobs I agree are a different kettle of fish to the normal hob. They pulse power rather that deliver a steady load and so don't work as such on a thermostatic range. What they do though is power share so when you put a cold pan on them they "rob" power from other areas, so in a way at cold start up with pots and pans there is a good chance that like a conventional hob they will be using full power. But once the pans warm and your cooking away the power loading will drop on them.

The guiding light for Induction hobs are the manufacters instructions as is with all equipment, just more so with thses. What they tell you then that is what you fit.

 

[Engineer54]

Well unless I misread it sounds like you haven't got a suitable supply for your new hob, you need a dedicated circuit large enough for the hob. The oven can be connected to the existing socket assuming it has a plug.

That was an opinion given on DIYnot forum, and appears to be a common one. hence my confusion. All the posts on that forum appear adamant that a new circuit is required for induction hobs.​

Are you saying, that my cooking loads are too big for the supply it's connected too?? Well i can assure you there Not!!! I have a two CCUs separately fed from the cooker unit, as the oven combined load is a bit too large for a FCU or socket outlet!! My combined load is around 13.8KW

Our dinner parties by the way can easily compared to the always quoted Xmas dinner, in terms of cooker usage. I guess it's up to you if you want to listen to comments on a DIY forum, i'll stick to the tried, tested and proved Diversity formula myself!!!​