[Closed] Induction Hob - 13A Plug or beast mode? Sparkies...?

7400+3800= 11200watts.
11200/230=49A (rounded up)
First 10A then 30% of remaining.
39Ax30%=11.7A
11.7+10=21.7A
Crack on. You’ll be fine.

my sums suggest you'd pop the MCB with what you have already if you ran everything flat out.

13a induction hobs really aren't great, I'd have the full power if I were you.

Crack on. You’ll be fine.

Really?
Hob on full =7400kw.
7400/230 = 32A

If you have the hob on full and turn the oven on you will trip the MCB - the hob needs it's own supply.

Being able to bring two pans of water to the boil very quickly is one of the big benefits of an induction hob - if the electric work isn't too difficult/expensive it's well worth it. (our wide induction hob has a 10kw connection!)

Diversity is your friend, as is thermal lag.

As a very highly qualified power engineer of some standing, I was highly embarrassed when my electrician pointed out to me that diversity applies to appliances like cookers too.

😳

"If you have the hob on full and turn the oven on you will trip the MCB - the hob needs it's own supply."

It really won't. Apply diversity as mentioned already.

Ideally I like a separate circuit for each but in reality you just can't sometimes.

Yes really.

For cooker circuits diversity is applied.
First 10amps then 30% of the remaining amps, plus 5amps if there is a socket outlet on the switch plate.
I’ve got a 7400w hob and a 3600w oven on a 32a radial circuit.

huh. i learned something today. ta.

Thanks for the info - especially about 13a induction hobs being a bit crap.

I had done the maths on the diversity so glad it has been validated here. There is a single pole cooker connection that currently has both hob and cooker wired in to it - I wired the cooker in myself can I stick with that?

Any recommendations on hobs other than the Ikea one I am keen on?

“Diversity” is just a way of saying “not everything will be running at full power at the same time”

I’m not sure that’s a safe assumption with an induction hob. When you put a ring on ‘boost’ to boil a pan it pulls it’s full power continuously. You might not get up to the full 7.4kw but I’m guessing you could get very close - check what the max power output of each ring is on the hob.

If you then switch the oven on and ask it to get up to 200C it will pull full current from the element as it heats up (once up to heat it will switch on and off controlled by the stat).

I’m not an electrician or a power engineer but it seems to me that there would be a real risk of the MCB tripping based on the likely use of the two appliances.

“Diversity” is just a way of saying “not everything will be running at full power at the same time”

Yup, exactly that. If you really want to know how it works, not as simple as a few calculations would have you think, spend a few weeks trying to understand the 17th edition regs (or get a spark in)

I’m not sure that’s a safe assumption with an induction hob

As I said, I’ve a similar set up and I’ve never had any tripping issues.
A 32a mcb doesn’t trip as soon as it hits 32a.

Simons - you’d be horrified what we do with power networks then.
We allow 1 to 2 kW per house on a large estate, 12kW plus 1 to 2 kW on a medium estate - bit more on a small one.
Your individual house supply is probably rated at 18kW (varies a bit depending on where you are and how old your house is) - so if you have an electric cooker, kettle, tumble dryer, fridge, freezer, shower, washing machine, dish washer, lights... well you add the up, but altogether they probably peak around 12-15 kW, far less than the addition suggests.
So one house peaks at 12-15kW but for say 1000 houses we might allow 900kW (not 12,000kW) - about 7.5% of what the straight addition would suggest.
But it works, and it keeps costs to customers down as they don’t end up paying for network they don’t need.

A 32a mcb doesn’t trip as soon as it hits 32a.

I had been wondering about checking the tripping characteristic for an MCB, but hadn’t got round to it.

Any recommendations on hobs other than the Ikea one I am keen on?

Not really, The Ikea one at £349 looks as good as anything else I looked at out there, has everything worth having that my twice that price Samsung has. 5 year guarantee as well (Samsung only gave me 2yr). Only advice is to check the min pan diameter and don't go out and buy any pans too small (ie milk pan), like I did. If you love your old pans, you can buy induction mats, don't know how well they perform tho.

only thing that didn't live up to expectation was from everyone raving about it boiling water much quicker than an electric kettle, so you'll never use your kettle again. That lasted about 5 goes before I decided that a kettle is actually more practical, even if it does take 30 seconds longer.

A 32a mcb doesn’t trip as soon as it hits 32a

Having said that, never let the design current exceed the nominal rating of the MCB. Other MCB types (C, D, etc) will probably take too long to trip in a domestic setting, so don't be tempted down that path either 🙁

Cheers Folks - IMG - I like the info about the power network!

B.A.- Yes I agree about the IKEA hob, I was looking at a Siemens to match the oven but at over £100 more and no 'bridge' function the difference we save pays for a couple of new pans to go with the induction compatible Circulon pans we already have.

Yup, exactly that. If you really want to know how it works, not as simple as a few calculations would have you think, spend a few weeks trying to understand the 17th edition regs (or get a spark in

I did just that when I specced and installed the circuits on our house. Since our hob was ?10kw and on an island it got it’s own feed. Surprised at that calc for Ovens/hobs but if it works it works.

Surprised at that calc for Ovens/hobs but if it works it works.

It's an assumption. If you have everything going full bore for the Chrimbo dinner then you might have problems

Which was my point! 🙂

It works. If it doesn’t your lights are going off On the third Thursday in December around 6pm. Every year.

Thermal lag (which is the other thing I mentioned) means you can go above 32A for a good long time before there is actually any problem. MCB trip time characterics mirror this. The one I checked gave you about 2hrs 45minutes before it would trip at at say 33-35A

That logic could be applied to all circuits.
32a ring final, a kettle, toaster, a hair dryer and a few others will put it over 32a.
Then if your hobs on, oven, tumble dryer and washing machine etc, you might just be over the main fuse rating, also as Img stated if more than 7:5% of an estate does the same the supply is overloaded!
That’s why these maximum demand formulas are in place.
There is a slight chance that it might trip and if it’s feasible, run a new supply, but if not, it’ll be fine, he might have to put up with cold carrots once a year.

^ **** all that, get gas!

An interesting discovery I made recently, when the Chargemaster chap installed a 32A EV charger on a 16A MCB, is that it would only trip after about 30 - 40 minutes at the full load of 7.7kw (the first time, anyway; it would get quicker rapidly after that).

Indeed phiiiiil. Thermal lag as modelled by the MCB. Correct operation

it would only trip after about 30 - 40 minutes

ABB characteristic suggests up to 4 minutes at 2 pu current. But up to an hour at 1.5 pu current.

How sure are you that the charger was actually taking 2 pu current? - that’s the maximum it would take and it will be software controlled to preserve the battery life.