7. 3 kw INDUCTION HOB

[Angefoh]

Can I run a 7.3Kw induction hob off of 2 x 16 amp circuits single phase I'm not sure what size cable is installed, I will check.
Would I be be able to run with the 2 x 16amp breakers or should I install a single 32 amp breaker with separate RCD?
Thanks in anticipation.

 

[Grant1987]

Can I run a 7.3Kw induction hob off of 2 x 16 amp circuits single phase I'm not sure what size cable is installed, I will check.
Would I be be able to run with the 2 x 16amp breakers or should I install a single 32 amp breaker with separate RCD?
Thanks in anticipation.

Get an electrician in mate. He will advise you on the correct way to install such equipment

 

[Dustydazzler]

Running things dual phase is pretty unconventional over here

 

[Angefoh]

Get an electrician in mate. He will advise you on the correct way to install such equipment

I will do so but I just wondered if the existing circuits were enough, other wise I will get a larger cable, which I can at least buy and run myself without paying electricians fees initially.
But thanks for the reply

 

[Risteard]

I will do so but I just wondered if the existing circuits were enough, other wise I will get a larger cable, which I can at least buy and run myself without paying electricians fees initially.
But thanks for the reply

Many Electricians will not connect wiring which your have done and will insist on running it again themselves.

 

[Angefoh]

Many Electricians will not connect wiring which your have done and will insist on running it again themselves.

OH really, OK I suppose safety and regs come into play. Still doesn't answer my question regarding existing installation though. But thanks.

 

[Angefoh]

Running things dual phase is pretty unconventional over here

The 2 x 16 amp feeds are on a single phase just separate breakers. Thanks for your reply.

 

[James]

as a general rule, a device shouldn't not be run from 2 different breakers unless they are physically interlocked so they trip together.
there are some exceptions but they are unlikely to come into play for your Hob.

 

[Angefoh]

as a general rule, a device shouldn't not be run from 2 different breakers unless they are physically interlocked so they trip together.
there are some exceptions but they are unlikely to come into play for your Hob.

Hi James, thanks for the reply. I know that the electrician that installed the 2 circuits was providing for an electric hob which I think do run one set of of rings for each circuit. Should I ask for a single 32 amp breaker to be installed?
I still need to check the size of cable he has installed.
I'm basically wondering if the existing wiring will handle the load?

 

[Taylortwocities]

Hi James, thanks for the reply. I know that the electrician that installed the 2 circuits was providing for an electric hob which I think do run one set of of rings for each circuit. Should I ask for a single 32 amp breaker to be installed?
I still need to check the size of cable he has installed.
I'm basically wondering if the existing wiring will handle the load?

Rings? I don’t think so!

 

[Angefoh]

Rings? I don’t think so!

By Rings I mean ceramic hobs. But do they not run on separate circuits????

 

[brianmoooore]

Running things dual phase is pretty unconventional over here

Fairly common in my part of the country, where there are loads of two phase farm supplies, but agree that it's unconventional for a domestic supply.
Unconventional doesn't make it wrong though, so I can't think of a reason to say it definitely shouldn't be done, although the MCBs should be a DP and the isolator a TP.
This all assumes that the hob is designed, like most modern ones, to be run from a three phase supply, and is supplied with links for the UK market. Two of the phase terminals would still have to be linked, so checks would need to be made that the max demand for these two didn't exceed the supply capacity.
Unless it's difficult or impossible, it would still be a lot simpler to fit a new supply cable of sufficient size for the hob.

 

[mainline]

The 2 x 16 amp feeds are on a single phase just separate breakers. Thanks for your reply.

It's more likely to be one for oven and one for hob.

Do these feed into separate switches/points ?

You still need to look at cables sizes.

 

[mainline]

Can I run a 7.3Kw induction hob off of 2 x 16 amp circuits single phase I'm not sure what size cable is installed, I will check.
Would I be be able to run with the 2 x 16amp breakers or should I install a single 32 amp breaker with separate RCD?
Thanks in anticipation.

The short answer is no.

 

[Angefoh]

It's more likely to be one for oven and one for hob.

Do these feed into separate switches/points ?

You still need to look at cables sizes.

The oven is on a separate breaker and the two other breakers are marked electric hob 1 and electric hob 2 . I need to pull out my cabinet to see where the cables/outlets are positioned and what size cable is provided. I have a feeling that there are two points and I wired into one of them for my gas hob ignition but that was 6 years ago so everything is a little hazy.
OK thanks for the reply.

 

[Other_Tucker]

Using all 4 burners at max? probably never. With one 16a MCB and one circuit it will probably never trip. If it does but both cables into one 32A MCB making a ring of 1 point.

*Assuming there's nothing else fed from these 16a circuits, the cabling is the right size, and you have a suitable cooker outlet or cooker isolator. Not wiring two 13a plugs together.

 

[mainline]

Using all 4 burners at max? probably never. With one 16a MCB and one circuit it will probably never trip. If it does but both cables into one 32A MCB making a ring of 1 point.

*Assuming there's nothing else fed from these 16a circuits, the cabling is the right size, and you have a suitable cooker outlet or cooker isolator. Not wiring two 13a plugs together.

He needs to get an electrician in.

 

[Lucien Nunes]

put both cables into one 32A MCB making a ring of 1 point.

A ring with a single point of load equalling the OCPD In isn't a valid configuration. A ring is intended to feed a distributed load that ensures reasonable current sharing. Instead this would form a radial circuit with two cables in parallel. As such, it is necessary to meet certain criteria to ensure that the current will be shared reliably and equally and not all transferred to one cable in the event of a bad connection etc. But if those criteria are met, this could be a valid solution.

Fairly common in my part of the country, where there are loads of two phase farm supplies, but agree that it's unconventional for a domestic supply.
Unconventional doesn't make it wrong though, so I can't think of a reason to say it definitely shouldn't be done, although the MCBs should be a DP and the isolator a TP.

In the split-phase scenario the neutral only needs to be the same size as one line, so you could make it into one split-phase 3-wire circuit. But with single-phase, both neutrals would be needed and would have to be separate all the way to the hob, so a 4-pole isolator would be required. That assumes the hob maintains electrical separation between the two circuits, which I don't think is a given. E.g. if one circuit is disconnected at the CU, can the hob be relied upon not to back-feed any leakage to it from the other? It's not intended to be fed from two independent circuits, only from different phases of one circuit, so they might not have allowed for this situation.

With one 16a MCB and one circuit it will probably never trip. If it does...

Not tripping is not a sufficient indication of a correctly designed circuit. There is a no-go zone where Ib>In but not 1.45 x In so not guaranteed to ever trip. This is a more insidious problem than a gross overload that does cause a trip and draws attention to itself. Instead it just cooks gently and shortens the life of the MCB and cable. The time/current characteristics of MCBs and fuses are intended to help avoid nuisance trips and be simple and reliable to implement. But they put the onus on the designer to avoid designing-in foreseeable moderate overloads.

 

[davesparks]

Should I ask for a single 32 amp breaker to be installed?

No, what you need to ask an electrician to do is have a look at the existing circuits and establish whether or not they are suitable for the new hob. And if they are not suitable then ask them to advise, and probably quote, to install a new suitable circuit.

All we know at the moment is that you have two circuits fed from 16A MCB's, we don't know anything about how they are installed, cable size/type etc.
As they were apparently installed to feed 2x hobs they may well be wired in a cable suitable for 32A but had smaller MCB's installed due to a change of plan. You mentioned a gas hob being connected to one of them, this may be the reason for changing to a 16A MCB.

And on another note, why would you change from a gas hob to an electric hob? Gas hobs are much nicer to cook on and cheaper to run.

 

[brianmoooore]

And on another note, why would you change from a gas hob to an electric hob? Gas hobs are much nicer to cook on and cheaper to run.

Completely and fully agree that gas is far superior for a hob, but a common reason for changing to electric is to avoid costly annual gas checks in rented property.

 

[davesparks]

Completely and fully agree that gas is far superior for a hob, but a common reason for changing to electric is to avoid costly annual gas checks in rented property.

This may be a regional difference but around here if a property has a gas supply then it is pretty likely to have gas heating too which negates that potential saving.

I would certainly be very upset if my landlord replaced the gas hob with electric, it was the main selling point for the flat as far as I was concerned when I viewed it.

 

[brianmoooore]

Gas heating and water changed to electric or oil as well, although my experience is mainly with LPG rather than natural gas.

 

[davesparks]

Gas heating and water changed to electric or oil as well, although my experience is mainly with LPG rather than natural gas.

I'm surprised that makes financial sense, a landlords gas inspection doesn't cost that much.

I wonder if it has anything to do with it being LPG and that being a different situation.

 

[brianmoooore]

Doesn't make sense (for the landlord) to just go in and do it, but when the property is being renovated, it does.
I have LPG hobs in my own house, but all the holiday cottages are electric cooking.

 

[mainline]

Completely and fully agree that gas is far superior for a hob, but a common reason for changing to electric is to avoid costly annual gas checks in rented property.

From a landlords point of view, electric oven and hob have benefits over gas both for, safety, and maintenance costs.

Gas for heating.

 

[mikey9]

Old thread, but for anyone with the same question who finds this, I'll add a picture from a Whirlpool cooktop manual.
It has two power inputs and appears to be quite flexible with voltage and phase.

So depending on your particular hardware, the answer may be technically yes, but would go against local code in UK and Australia.

 

[lenovo]

Hello,
i got slightly lost... what 1pole CB should be used with 7.3kw hob? ie how many ampers and what curve?
and also are we talking about 4 or 6mm cable?


edit> seems 32A, no clue regarding its curve and 6mm2 should be ok?


Appreciate.

 

[Taylortwocities]

Sorry.

With respect, you are considering a brand new circuit. That is notifiable work and not a DIY project.
You need a registered electrician to do this work for you, to test, certify the installation and notify the local authority that the work complies with building regulations.

 

[lenovo]

@Taylortwocities not going to do it by myself.

Just want to know and check hows the cable will look like... and want to buy online material... work will be done by certified guy.

 

[James]

@Taylortwocities not going to do it by myself.

Just want to know and check hows the cable will look like... and want to buy online material... work will be done by certified guy.

Simple, just ask your electrician what they want you to order.

 

[nicebutdim]

The bottom line is that a number of factors need to be taken into account in determining cable size and these would require knowledge no one here is in possession of. A quick visit from your electrician would provide the answer.

 

[lenovo]

he should come on next week... but in the general i dont believe to these ppl here in the country where i am located atm.
so 2nd opinion should be nice.

 

[lenovo]

and here 7.6kW Induction Hob - need to select cable and fuse size - https://www.electriciansforums.net/threads/7-6kw-induction-hob-need-to-select-cable-and-fuse-size.68239/page-2#gsc.tab=0 they clearly stated
32A, 6mm...

 

[Taylortwocities]

That’s your second opinion then.

When I was “on the tools” I hated customers who bought their own materials. Often it was just plain wrong, or some cheapo tat that wouldn’t last a week. Or it hadn’t arrived. All of these added to time on thd job, and cost the customer more ££.
On more than one occasion I’ve just walked out to another job.
Look, It’s a new circuit. You’ll need a registered electrician, he/she has trained for years, is competent and is assessed annually. Trust him/her, you won’t save any money.

 

[lenovo]

That’s your second opinion then.

When I was “on the tools” I hated customers who bought their own materials. Often it was just plain wrong, or some cheapo tat that wouldn’t last a week. Or it hadn’t arrived. All of these added to time on thd job, and cost the customer more ££.
On more than one occasion I’ve just walked out to another job.
Look, It’s a new circuit. You’ll need a registered electrician, he/she has trained for years, is competent and is assessed annually. Trust him/her, you won’t save any money.

Bc I am currently in Czechia
I do not trust these people at all.

I am not in west eu or US... So it's pain here. So many diletans and I can imagine how they are assessed :/

 

[Risteard]

Bc I am currently in Czechia
I do not trust these people at all.

I am not in west eu or US... So it's pain here. So many diletans and I can imagine how they are assessed :/

Surely it's a three-phase supply there rather than a large single phase supply? You really need someone familiar with Czech wiring regulations and practices.

 

[lenovo]

@Risteard
i have electrian visit next week, i believe there is also 3-phase supply, do i have to ask him to setup it in 3-phase way? is that better then single phase supply with one big CB?

thanks

 

[lenovo]

He said i have 1phase 25A CB, and he said that my induction 7.3kw should work with it... that these are modern and know how to regulate power....

but he suggested that i should go for 2x 25A CB setup.

Confused.

 

[mainline]

He said i have 1phase 25A CB, and he said that my induction 7.3kw should work with it... that these are modern and know how to regulate power....

but he suggested that i should go for 2x 25A CB setup.

Confused.

It would probably work fine on the single phase due to diversity if nothing else.