UK Induction hob

[Bogart]

Have still not installed my Neff induction hob but is near. Was originally going to use 3phase but got battered on here so no. I have a 3 phase supply at home with 3 seperate Hager CUs. Red phase does the kitchen area, ring, lighting and a circuit marked cooker which fed a dual oven in 10mm2 via a 32 amp mcb. There is no RCD on the incomer just a 100 Amp switch. The sockets are via a 32amp RCBO, the lights via a 6amp MCB and the cooker via a 32 amp MCB. The original dual oven is to be replaced by 2 seperate ovens each of 13 amp max demand so total worse case is 26amp. The induction hob is limited to a maximum of 11kw approx 50 amp max. Easiest would be to run induction hob off the 10mm2 via an RCBO and run a 2.5mm2 from an RCBO to the ovens. Problem is I cannot find a 50 amp Hager RCBO. So could I run 2 of them in parallel? Alternatively change the 100amp switch for an RCD? Only problem I see here is Hager only do a 2 pole RCD with a 30mA trip at 63 amp max. If I want a bigger size 80 amp or 100 amp I need to go to a 100mA trip. Or should I just change the red phase cu?

 

[telectrix]

fit a 40A RCBO. hob will never pull over that except maybe for very short periods.

 

[DPG]

Two RCBOs in parallel?? Feeding one device?

 

[Bogart]

Two RCBOs in parallel?? Feeding one device?

Yes or is that a no no? The hob can be fed by 1,2 or 3 phases. So i thought run 2 seperate 2.5mm2 cables each off an RCBO, just in this case both on same phase.

 

[marconi]

https://www.winningappliances.com.au/public/manuals/Neff-T68TS61N0-Induction-Cooktop-User-Manual.pdf

see page 26/36 for this induction hob - is it the same as yours? If not not then look in the manual for your model of IH for the 'power management function - limiting the total power consumption of the hob'.

You can use the 10mm2 cable with its current 32A mcb if you set the power limit somewhere between 7 and 8kW. If you fit a 40A mcb/rcbo then the power limit can be increased to between 8 and 10kW.

Indeed for most 'normal' use of the hob you could most likely leave the power limit at maximum on a 40A mcb/rcbo and not be troubled by it tripping. On a 32A you might occasionally have trips when all rings are started on high at the same time with large pans of water in them.

For safety's sake you must ask a qualified electrician to confirm the installation method of the current 10mm2 cable will allow an increase in the size of the mcb before changing it from 32A.

 

[Bogart]

fit a 40A RCBO. hob will never pull over that except maybe for very short periods.

Hob is rated at 15kw but limits itself to 11.1kw maximum so that is the load it can pull without every ring being on. So methinks might be resetting a 40 A job regularly
[automerge]1577960332[/automerge]

https://www.winningappliances.com.au/public/manuals/Neff-T68TS61N0-Induction-Cooktop-User-Manual.pdf

see page 26/36 for this induction hob - is it the same as yours? If not not then look in the manual for your model of IH for the 'power management function - limiting the total power consumption of the hob'.

You can use the 10mm2 cable with its current 32A mcb if you set the power limit somewhere between 7 and 8kW. If you fit a 40A mcb/rcbo then the power limit can be increased to between 8 and 10kW.

Indeed for most 'normal' use of the hob you could most likely leave the power limit at maximum on a 40A mcb/rcbo and not be troubled by it tripping. On a 32A you might occasionally have trips when all rings are started on high at the same time with large pans of water in them.

For safety's sake you must ask a qualified electrician to confirm the installation method of the current 10mm2 cable will allow an increase in the size of the mcb before changing it from 32A.

Hi

No is not the same . The one you quote has an electrical connection rating of 7400W whereas mine is rated at 11100W. 10mm2 running as it does in a celing void, uninsulated has a rating around 45A, which to my mind is on the borderline hence my thoughts of just leaving that for the ovens using a 32 A RCBO and running a new circuit for the hob.
One thing that I queried with NEFF was the rating of the cable they supply. Never got a proper answer to that. One gets a single phase version using 4mm2 cable and a 3 phase version using 2.5mm2. I can see the 3 x 2.5mm2 being ok but the 4mm2 looks small to me considering the unit could want to draw 48A.
My original thought, way back was to use a 3 phase RCBO ie Eaton item 169639 a 3 phase 20A 30mA RCBO and feed the hob with 5 core 2.5mm2

 

[telectrix]

Hob is rated at 15kw but limits itself to 11.1kw maximum so that is the load it can pull without every ring being on. So methinks might be resetting a 40 A job regularly
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Hi

No is not the same . The one you quote has an electrical connection rating of 7400W whereas mine is rated at 11100W. 10mm2 running as it does in a celing void, uninsulated has a rating around 45A, which to my mind is on the borderline hence my thoughts of just leaving that for the ovens using a 32 A RCBO and running a new circuit for the hob.
One thing that I queried with NEFF was the rating of the cable they supply. Never got a proper answer to that. One gets a single phase version using 4mm2 cable and a 3 phase version using 2.5mm2. I can see the 3 x 2.5mm2 being ok but the 4mm2 looks small to me considering the unit could want to draw 48A.
My original thought, way back was to use a 3 phase RCBO ie Eaton item 169639 a 3 phase 20A 30mA RCBO and feed the hob with 5 core 2.5mm2

10mm is not 45A,if you look in BS7671 or onsite guide, you'll find that 10mm is 63A and 6mm is 46A .both ref. method C.which yours seems to be.(no insulation).

 

[Bogart]

10mm is not 45A,if you look in BS7671 or onsite guide, you'll find that 10mm is 63A and 6mm is 46A .both ref. method C.which yours seems to be.(no insulation).

I was working mine out using ref 100 as C makes no mention of being in a ceiling void.

 

[marconi]

Well this one is 11.1kW and it too has a power manager function see page 31 of:

https://media3.neff-international.com/Documents/9001387749_B.pdf

Have you checked yours does not or are you not bothered preferring not to limit the maximum power by running a new cable etcetera?

 

[telectrix]

I was working mine out using ref 100 as C makes no mention of being in a ceiling void.

in a void, with no insulation affecting heat dissipation, it's ref. C.

 

[Bogart]

Well this one is 11.1kW and it too has a power manager function see page 31 of:

https://media3.neff-international.com/Documents/9001387749_B.pdf

Have you checked yours does not or are you not bothered preferring not to limit the maximum power by running a new cable etcetera?

Yes I can limit the maximum power of the hob but only up to the figure of 4Kw. Bit pointless having 15Kw of available hob element and setting the maximum to 4Kw. I will leave the hob to set its own maximum which in the case of my hob is 11.1Kw
Hence I need a circuit/s capable of handling 11.1Kw

 

[Bogart]

[automerge]1577988230[/automerge]

in a void, with no insulation affecting heat dissipation, it's ref. C.

Was basing it on this

BS7671 17th Editon Reference Method	Example of installation method
A	In conduit in an insulated wall with the conduit close to or touching the inner skin.
B	Enclosed in conduit or trunking on or in a wall.
C	Clipped direct, or sheathed cables embedded directly in masonry, brickwork, concrete, plaster or the like (other than thermally insulating materials)
100	Above a plasterboard ceiling covered by thermal insulation, insulation thickness less than 100 mm.
101	Above a plasterboard ceiling covered by thermal insulation, insulation thickness greater than 100 mm.
102	In a stud wall with thermal insulation with the cable touching the inner wall surface.
103	In a stud wall with thermal insulation with the cable NOT touching the inner wall surface.

Has this cnaged in the 18th edition. My celing void has no insulation so reference method 100 is a worst case scenario

 

[DPG]

Is that meant to be a sensible comment or not?
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Was basing it on this

BS7671 17th Editon Reference Method	Example of installation method
A	In conduit in an insulated wall with the conduit close to or touching the inner skin.
B	Enclosed in conduit or trunking on or in a wall.
C	Clipped direct, or sheathed cables embedded directly in masonry, brickwork, concrete, plaster or the like (other than thermally insulating materials)
100	Above a plasterboard ceiling covered by thermal insulation, insulation thickness less than 100 mm.
101	Above a plasterboard ceiling covered by thermal insulation, insulation thickness greater than 100 mm.
102	In a stud wall with thermal insulation with the cable touching the inner wall surface.
103	In a stud wall with thermal insulation with the cable NOT touching the inner wall surface.

Has this cnaged in the 18th edition. My celing void has no insulation so reference method 100 is a worst case scenario

Ref 100 is 'covered by thermal insulation'. See Tel's post above.

 

[Bogart]

Ref 100 is 'covered by thermal insulation'. See Tel's post above.

Agree but could only be 1mm ie amounting to near as damn it zero.

 

[DPG]

Agree but could only be 1mm ie amounting to near as damn it zero.

Is there any insulation though?

 

[Bogart]

Is there any insulation though?

None, no insulation at all plasterboard below floorboards above.

 

[DPG]

None, no insulation at all plasterboard below floorboards above.

But method 100 is covered with insulation. I think I'm missing something here.

 

[telectrix]

as there's no insulation, 100 and 101 are not applicable by definition

 

[davesparks]

Have still not installed my Neff induction hob but is near. Was originally going to use 3phase but got battered on here so no. I have a 3 phase supply at home with 3 seperate Hager CUs. Red phase does the kitchen area, ring, lighting and a circuit marked cooker which fed a dual oven in 10mm2 via a 32 amp mcb. There is no RCD on the incomer just a 100 Amp switch. The sockets are via a 32amp RCBO, the lights via a 6amp MCB and the cooker via a 32 amp MCB. The original dual oven is to be replaced by 2 seperate ovens each of 13 amp max demand so total worse case is 26amp. The induction hob is limited to a maximum of 11kw approx 50 amp max. Easiest would be to run induction hob off the 10mm2 via an RCBO and run a 2.5mm2 from an RCBO to the ovens. Problem is I cannot find a 50 amp Hager RCBO. So could I run 2 of them in parallel? Alternatively change the 100amp switch for an RCD? Only problem I see here is Hager only do a 2 pole RCD with a 30mA trip at 63 amp max. If I want a bigger size 80 amp or 100 amp I need to go to a 100mA trip. Or should I just change the red phase cu?

No you can't take a phase from each seperate CU to feed the appliance.
No you can't connect two protective devices in parallel, especially not with residual current devices.
No you cannot use anything other than a 30mA residual current device to satisfy the requirements of additional protection. The regulations specify 30mA protection as this is the highest value at which most healthy people will probably survive an electric shock.

Unfortuantely your understanding of the electrical regulations and electrical safety seems to be lacking to the point that you could put yourself or others in serious danger so the best advice we can give you is to recommend that you engage an electrician to carry out the work.

 

[SparkyChick]

I'm going to close this thread.

@Bogart , whilst we don't approve of members giving this advice, there is a time and place for it to be given and that time is now.

It appears from having a read of this thread that you lack the knowledge and understanding to conduct this work safely, therefore the best advice any professional on these forums can give you is to seek out the services of a qualified local electrician. We have a directory section (Find an Electrician | Electricians Directory - https://www.electriciansforums.net/local-electricians/), you may be able to find one there. Failing that get a couple of recommendations from family, friends and colleagues.