7. 3 kw INDUCTION HOB

[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.