Belling 900mm Oven with Induction top - Questions - But not looking for DIY solution

Forums › Home Workshop DIY › Belling 900mm Oven with Induction top - Questions - But not looking for DIY solution

WanaGo

149 posts

Master Geek

#302240 9-Nov-2022 12:14

Hello,

I am not looking to do this DIY - however just trying to pick brains for ideas.

We had a sparky here today and he is going to come back to me with options too, but I just wanted to think in parallel.

We had a 900mm oven which has a gas top, so was on a 15A plug. 6.0mm cable was running to it, so was heaps of capacity. It died, so we replaced it with a Belling BCC900IB.
The nameplate on the oven states 240V 16380W of which the Induction unit is 7400W. 16KW!
It is capable of being wired in single phase, or 3 phase. It comes in Single phase configuration, and has jumpers which can be removed to then wire it in 3 phase (or dual phase if you wish). Phase wise it could just be 3 circuits, not actually 3 phases.
Single phase seems ridiculous as to how you would even do that, do you have to use 10mm cable or something...?
3 phase over 6.0mm cable seems like the typical solution I would think.

So currently we have a single 6.0mm TPS running about 5 meters from the meter box, 32A breaker.

The sparky is suggesting we just run another 6.0mm TPS in parallel, have the induction on 1 of them, and the ovens on the other, both on 32A breakers. So dual phase in a way.

We currently do not have any sort of oven switch near the oven, which needs to change too (based on this - near the bottom - https://www.level.org.nz/energy/electrical-design/wiring/fixed-wiring-for-electrical-systems-and-appliances/).
The only real solution I found to this was a PDL 1 gang 2 pole switch like this, https://eref.se.com/au/en/pdl/product-pdf/PDL647WH
However this is 45A rated, but 20AX (which is 20A when used with an inductive load). 20A @ 240V is 4800W, which is not enough for the nameplate induction of 7400W.
So I am not even certain this switch is going to be suitable.

So I am just not sure what is best for A) a switch, or B) the wiring.

16380W is everything turned on full load, which is unlikely to happen, and I believe I heard the sparky mention you only need to wire for something like 70% of the Max, which is still 11KW, and 5W or so for the induction (I may have heard wrong though - so don't quote me on this).

The only switches that seem to be available for true 3 phase are industrial ones, and those obviously are not nice to look at for wall mounting in a residential kitchen. This is a residential oven, not a commercial one, just purchased from Harvey Norman. My mother in law has one from about 10 years ago in her kitchen, but hers is Gas top, not Induction, so quite a difference in power there.
So I really am just looking to see what solutions are 'normal' for something like this.

I know the code states you need a switch on the wall in the kitchen, but if there is no switch that can switch 3 phase or single phase (or dual phase) at the current required that is suited to residential, what do you do?

Another option is run a single phase to a switch, and that switch turns on a 2 or 3 phase contactor in the ceiling, which then switches the mains for the oven - but that just seems overkill.

Any Sparkies here or people with knowledge know what the 'best' solution to this would be?

Thanks

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149 posts

Master Geek

#2993949 9-Nov-2022 12:30

Wiring diagram image above I just realised is 1 page of 3, it shows the left, right and induction parts on different pages, and how they are connected to that terminal block - just FYI.

hamish225

1418 posts

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#2993953 9-Nov-2022 12:36

Following because we're on a 63amp (15kw) single phase supply and I'd like to get an oven similar to yours when the time comes, but if they use more than our entire supply that may not be possible 😅

*Insert big spe*dtest result here*

pipe60

127 posts

Master Geek

#2993987 9-Nov-2022 14:37

Max demand on a cooking appliance can be 50% of connected load,so the 2 6mm cables will be suitable, Hager do a 45a 2 pole switch or use contactors as per your electricians recommendation, your oven is single or 2 phase only,

WanaGo

149 posts

Master Geek

#2993988 9-Nov-2022 14:51

pipe60:

Max demand on a cooking appliance can be 50% of connected load,so the 2 6mm cables will be suitable, Hager do a 45a 2 pole switch or use contactors as per your electricians recommendation, your oven is single or 2 phase only,

50%, ok, that is a bit of a difference.

is the Hager 45A 2 pole also 45A for Inductive load though, or is it like the PDL one and its 20AX rated ?

The wiring diagram I posted is only 1 page of 3, it uses all 3 contacts, so is 3 phase or single phase. Trying to split it for 2 phase will be somewhat interesting, as the 3 oven parts and induction parts are split over the 3 phases.

Ill take some more photos of the 3 diagram pages.

Thanks

pipe60

127 posts

Master Geek

#2993999 9-Nov-2022 15:26

Yes it is 3 phase after seeing the the other diagrams.

https://www.ideal.co.nz/nzi/Category/Wiring-Devices/Switches/Allure-Cooker-Switch-40A-2Pole-Horiz-Gloss-White/p/HAGWBHCKSH1

Its 40A not 45A

How many phases do u have for the house?

WanaGo

149 posts

Master Geek

#2994008 9-Nov-2022 16:15

pipe60:

Yes it is 3 phase after seeing the the other diagrams.

https://www.ideal.co.nz/nzi/Category/Wiring-Devices/Switches/Allure-Cooker-Switch-40A-2Pole-Horiz-Gloss-White/p/HAGWBHCKSH1

Its 40A not 45A

How many phases do u have for the house?

We have 3 phase into the house fuse panel, 3 phase meter etc, and phases are split over various parts of the house. Incoming cable of all 3 phases is about 25mm wide.

Issue with using 3 phase on the oven though is finding a 3 phase residential switch to mount near the oven, that is not an ugly industrial switch. I just cant find one.

SomeoneSomewhere

1804 posts

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#2994045 9-Nov-2022 18:57

Tell your sparky to have a read of Table C4, which says that any domestic cooking appliance rated >13kW can be considered 40A for the purpose of subcircuit sizing. You've got three phase so spreading the load would be preferable, but that's a reasonable starting point.

You don't need a switch rated for inductive load. The majority of the load is heating (resistive) and the induction cooktops are likely fairly resistive due to PFC. In addition, it would be *very rarely* expected to operate under load.

Legrand also does a 40A two-pole.

I would probably be using two 32A circuits and just trying to balance the load approximately.

While one could argue that it's not strictly compliant as the standard specifies *a switch*, two or three separate single-pole switches, appropriately marked, would also be an effective solution. There's no multiphase loads so no need for simultaneous operation, and it's what gets done for separate hob and oven situations.

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johno1234

2808 posts

Uber Geek

#2994232 10-Nov-2022 08:27

As mentioned above, this is normal for large ovens with powerful induction cooktops. It is possible that if you crank everything up to max, set all the zones on the cooktop to the max with the turbo heat option on, that you will simply pop the circuit breaker.

In practice, this isn't going to happen.

Unless you are using your oven to power a steam turbine or something.

WanaGo

149 posts

Master Geek

#2994297 10-Nov-2022 10:33

johno1234:

As mentioned above, this is normal for large ovens with powerful induction cooktops. It is possible that if you crank everything up to max, set all the zones on the cooktop to the max with the turbo heat option on, that you will simply pop the circuit breaker.

In practice, this isn't going to happen.

Unless you are using your oven to power a steam turbine or something.

Yeah - unless of course we have all ovens going and pots/pans on the top, cooking for xmas dinner for all the relatives etc - it could be possible to push it - but I would think once things get up to temp the current draw drops right off. Turning everything on max at the exact time is unlikely to happen as you say.

WanaGo

149 posts

Master Geek

#2994304 10-Nov-2022 10:44

SomeoneSomewhere:

Tell your sparky to have a read of Table C4, which says that any domestic cooking appliance rated >13kW can be considered 40A for the purpose of subcircuit sizing. You've got three phase so spreading the load would be preferable, but that's a reasonable starting point.

You don't need a switch rated for inductive load. The majority of the load is heating (resistive) and the induction cooktops are likely fairly resistive due to PFC. In addition, it would be *very rarely* expected to operate under load.

Legrand also does a 40A two-pole.

I would probably be using two 32A circuits and just trying to balance the load approximately.

While one could argue that it's not strictly compliant as the standard specifies *a switch*, two or three separate single-pole switches, appropriately marked, would also be an effective solution. There's no multiphase loads so no need for simultaneous operation, and it's what gets done for separate hob and oven situations.

Thanks for this, really good info.

Yes I think we likely will be doing 2x 32A circuits, and trying to balance/share the 3 terminals on the oven as best as possible over the 2 circuits.

Either the PDL647 type double pole switch, which is now 40A rated on each pole (was 45A but not new models apparently), or say the Clipsal C2031D32 which is 32A rated on each pole - something like that should be fine I would guess. The Legrand one you mentioned, is it like this?
https://www.legrand.com/ecatalogue/572081-double-pole-switch-arteor-40.html this looks like the US version, I cant seem to spot a NZ one. Do you have a link by chance?

Still just baffles me how we have these 3 phase ovens sold here, but not a suitable residential 3 phase switch to match it, available. The 2 pole switch options will get us to where we need to be, but then trying to split the Left, Right and Induction over the 2 circuits, when they are hard wired into 3 terminals, is going to be a bit of a guess really. Single phase I guess is a possibility, with a 40A switch and wiring to suit 40A based on Table C4, but that just doesn't feel right.

Thanks

pipe60

127 posts

Master Geek

#2994363 10-Nov-2022 13:53

You have 3 phase might as well use it, switch a contactor back at the board or somewhere you have room.otherwise 2 pole range switch on 2 phases.

mdooher

Hmm, what to write...
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#2994364 10-Nov-2022 13:54

Wiring up those switches by pulling out the phase conductor in each 6mm cable is going to be really painful.

When I do this I always use either one or two DIN rail mounted 40A contactors and just run 1mm out to the switch.

just think, if you want, you will then be able to do cool things like shut down your cooktop/oven when the smoke alarm goes off (assuming you have an alarm system)

Matthew

elpenguino

3427 posts

Uber Geek

#2994396 10-Nov-2022 15:08

mdooher:

Wiring up those switches by pulling out the phase conductor in each 6mm cable is going to be really painful.

When I do this I always use either one or two DIN rail mounted 40A contactors and just run 1mm out to the switch.

just think, if you want, you will then be able to do cool things like shut down your cooktop/oven when the smoke alarm goes off (assuming you have an alarm system)

That's right - two hob + one oven switches in one flushbox will be a lot of thick conductors to manage.

Using a contactor is a bit more elegant and flexible and if the switchboard already supports DIN mount devices then it looks like the way to go.

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SomeoneSomewhere

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#2994464 10-Nov-2022 21:20

My reading is that a contactor isn't strictly compliant. The switch has to operate in all active conductors.

This is the Legrand double pole one.

The UK seems to have a lot of three-pole domestic style switches and I'd have relatively few qualms about importing one of those from a reputable source.

Depending on the exact construction of the terminal blocks, it's likely to be possible to move loads between phases, as each one is likely just a spade lug. Looks like 2x LH ovens, 1x RH oven, and 2x cooktop.

Scott3

3972 posts

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#2994535 10-Nov-2022 23:53

I would just own the appearance of an industrial-style switch.

I think the below would look good mounted on a wall near the cooker. Lets face it, that cooker look pritty serious in it's own right:

PDL PDL56SW3632LECG Switch 2Gang 63A 3P 500V IP66 Chemical Grey - SHOWTECHNIX

https://www.pdl.co.nz/products/detail?CatNo=PDL56SW3632LE&itemno=PDL56SW3632LECG&tab-document-1=0

https://www.showtechnix.co.nz/store/pdl-pdl56sw3632lecg-switch-2gang-63a-3p-500v-ip66-chemical-grey/

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WanaGo:

16380W is everything turned on full load...

Not according to the technical data you posted.

Every hob on boost would be 14.9kW, however, the maximum load for the hob top is 7.4kW. How this works (and is standard on most induction cooktops), is the cooktop simply won't let you turn everything on full load. My induction cooktop has two pairs of elements. If either of the pair is on boost, the other can be at a max setting of 6.

In terms of operation, it isn't too much of an issue, but especially as you are running wire anyway, I would try to size wires and breaker to handle the full load.

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I would say, if you have three phase, might as well use it.

Not sure of how the 70A load balanced between phases, but if it is even, it would be 23A per phase, well within the 32A that the existing 6mm^2 run can provide (just need two more cores).

If the load is evenly spread, doing two phase, would have L1 at 23A, and L2+L3 (bridged) at 46A, the latter likely requiring a wire fatter than the common 6mm^2. (And would need to go on a phase that is otherwise lightly loaded)

Altering the appliance to improve load balance doesn't really seem worth it to save a single core of 6mm cable, given wire is already being pulled.

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