RCBO rating for ovens and hob

[Pettens]

What rating of RCBO is required to run one oven (3600w) and one microwave (3600w) total 7200w. supplied by one 10mm cable?

Cable run is total of 15m from CU with 2.5m behind insulated stud wall, 3m under floor tight pace with other cables and pipes with insulation. And 9.5m in roof space clipped to joists with 100mm insulation bellow cable.

What rating of RCBO is required for the induction hob at 7600w and is supplied by its own 10mm cable running the same dimensions as above?

I would like to fit one of the control switches combined with a 13a socket facility. Which one of the two circuits would you suggest I place it on?

 

[riveralt]

What rating of RCBO is required to run one oven (3600w) and one microwave (3600w) total 7200w. supplied by one 10mm cable?

That's a very large microwave - is it a commercial one?

Cable run is total of 15m from CU with 2.5m behind insulated stud wall, 3m under floor tight pace with other cables and pipes with insulation. And 9.5m in roof space clipped to joists with 100mm insulation bellow cable.

After diversity with cooker switch/socket = approx 22amps
10mm cable through insulation = derate by 50% = approx 22amps
RCBO = 20Amps (Edited)

What rating of RCBO is required for the induction hob at 7600w and is supplied by its own 10mm cable running the same dimensions as above?

After diversity with cooker switch/socket = approx 22amps
10mm cable through insulation = derate by 50% = approx 22amps
RCBO = 20Amps (Edited)

I would like to fit one of the control switches combined with a 13a socket facility. Which one of the two circuits would you suggest I place it on?

Either - but I would get rid of the cooker socket and stick with a single cooker switch - in which case the post diversity load becomes approx 17amps

 

[ericmark]

The RCBO is there to protect the cable and 10 mm cable is somewhere around the 45A mark.

behind insulated stud wall

Means it could be well below this Reference Method 103# (in a stud wall with thermal insulation with cable not touching the inner wall surface) is 32A for example.

If the manufacturer has stipulated an external protective device which he can do for built in stuff then it is as recommended by manufacture.

If all items are supplied from same device then there is some diversity but careful with induction hob. Often induction hobs have cooling fans and as a result we don't want them to trip the breaker. Because of the Boost feature often there is no diversity. They vary on supply mine is stand alone and only requires a 32A supply for hob and oven but this is unusual I think only Belling make a stand alone unit. I can only use two hobs on boost at any one time so max of 6.7 kw for pair (29 A) but one fitted in parents house allowed the other one of pair to be still used in A mode so with 2 set to A and 2 set to P that was around 10 kw (43 A).

Mine could be overloaded if oven used as well not sure on size of elements but bottom oven has 3 elements (Top, Bottom and Back) selectable so only 2 used at same time. And top oven has 2 elements so I would expect if all were switched on together would be around the 50 A but the manufacturer says protect to 32 A so that's what I have done.

My parents oven alternates between the two elements and does not use both together so it can be supplied with a 13A supply.

With all that in mind there is only one option. Read the manuals as there are so many different ways that manufactures use to keep power within limits.

 

[Pettens]

What rating of RCBO is required to run one oven (3600w) and one microwave (3600w) total 7200w. supplied by one 10mm cable?

That's a very large microwave - is it a commercial one?
No, Its a domestic NEFF micro with additional standard oven capability

Cable run is total of 15m from CU with 2.5m behind insulated stud wall, 3m under floor tight pace with other cables and pipes with insulation. And 9.5m in roof space clipped to joists with 100mm insulation bellow cable.

After diversity with cooker switch/socket = approx 22amps
10mm cable through insulation = derate by 50% = approx 22amps
RCBO = 32Amps

What rating of RCBO is required for the induction hob at 7600w and is supplied by its own 10mm cable running the same dimensions as above?

After diversity with cooker switch/socket = approx 22amps
10mm cable through insulation = derate by 50% = approx 22amps
RCBO = 32Amps
As 7600w divided by 240v = 31.66 would it not be better to have a 40A RCBO?

I would like to fit one of the control switches combined with a 13a socket facility. Which one of the two circuits would you suggest I place it on?

Either - but I would get rid of the cooker socket and stick with a single cooker switch - in which case the post diversity load becomes approx 17amps

The only reason I was planning on a cooker socket rather than just the switch was to increase flexibility of utilising a 13a appliance on that particular part of the worktop. If the cooker socket was fitted to the hob circuit would this then justify a 40A RCBO?

 

[Pettens]

The RCBO is there to protect the cable and 10 mm cable is somewhere around the 45A mark.

behind insulated stud wall

Means it could be well below this Reference Method 103# (in a stud wall with thermal insulation with cable not touching the inner wall surface) is 32A for example.

If the manufacturer has stipulated an external protective device which he can do for built in stuff then it is as recommended by manufacture.

If all items are supplied from same device then there is some diversity but careful with induction hob. Often induction hobs have cooling fans and as a result we don't want them to trip the breaker. Because of the Boost feature often there is no diversity. They vary on supply mine is stand alone and only requires a 32A supply for hob and oven but this is unusual I think only Belling make a stand alone unit. I can only use two hobs on boost at any one time so max of 6.7 kw for pair (29 A) but one fitted in parents house allowed the other one of pair to be still used in A mode so with 2 set to A and 2 set to P that was around 10 kw (43 A).

Mine could be overloaded if oven used as well not sure on size of elements but bottom oven has 3 elements (Top, Bottom and Back) selectable so only 2 used at same time. And top oven has 2 elements so I would expect if all were switched on together would be around the 50 A but the manufacturer says protect to 32 A so that's what I have done.

My parents oven alternates between the two elements and does not use both together so it can be supplied with a 13A supply.

With all that in mind there is only one option. Read the manuals as there are so many different ways that manufactures use to keep power within limits.

Thanks for the detailed info on your set up. It helps to get a better understandig. Regarding the manufacturers manuals, unfortunately NEFF do not provide the necessary information to protect the circuits and appliances. Hence why I am trying to get a feel from this forum. Thanks again

 

[riveralt]

The only reason I was planning on a cooker socket rather than just the switch was to increase flexibility of utilising a 13a appliance on that particular part of the worktop. If the cooker socket was fitted to the hob circuit would this then justify a 40A RCBO?

Red markings - reminds of school - are you a teacher?

BTW we use 230v now!
EDIT - actually having re read my initial response that is wrong (I have now edited the original post)

The fact that the current carrying capacity of the cable has been de-rated to such a degree (because of the insulation) - down to 22Amps. And the RCBO is there to protect the cable - you should therefore use an 20Amp RCBO - not 32Amps.

 

[ricicle]

I think you boys ought to read up on the current carrying capacity of 10mm² cable !

 

[riveralt]

I think you boys ought to read up on the current carrying capacity of 10mm² cable !

Ricicle Thank you - I've found it in the OSG - shouldn't do things from memory.

I had worked on the basis of 43Amps for multi-core pvc ref method A based on the info given by the OP forgetting that Ref method A already takes that into account - So a 32Amp RCBO should be okay at the end of the day.

 

[securespark]

FWIW, with this install, I would not apply diversity. Especially not to the socket: diversity allows 5A, but you intend to make use of the full 13.

 

[ericmark]

NEFF like many other suppliers are primary aimed at the Europe market and the 16A supply with their radial system.

When using these grey imports one has to wire as they do in rest of Europe and take a 16A radial to each unit.

I have commented in the past on how Turkish manufactures can give all details but German seem to want to keep it all to registered dealers.

The NAFF range is good but the info supplied somewhat lacking I agree. There are 15 and 16 amp sockets and the idea of being able to unplug for maintenance is good. I have in the past done the same with immersion heaters so plumbers do not need an electrician to disconnect.

The problem is in UK the Type F CEE 7/4 (German "Schuko" 16 A/250 V grounded) socket is not permitted it does not comply with 553.1.2 Except for SELV or a special circuit from Regulation 553.1.5, every plug and socket-outlet shall be of the non-reversible type. with provision for the connection of a protective conductor.

Although there are sockets that we can use BS EN 60309-2 for example these are not neat and I would not want one in my kitchen.

Answer Buy British!

 

[DetlefSchmitz]

Answer Buy British!

For example...?

 

[ban-all-sheds]

{a mess}

Quotes can be

nested

And

they

can

be

stacked

Please practice.

 

[ericmark]

Answer Buy British!

For example...?

Belling made in Merseyside

 

[sparkypaul1957]

er ......am i missing something here , is nt DIVERSITY only applicable to meter tails and sub main cables , NOT to actual circuits ????

So, er you cannot make use of the diversity calculation for choice of protective device .....

Plse enlighten me if i m mistaken ....thanx.

 

[PrenticeBoyofDerry]

er ......am i missing something here , is nt DIVERSITY only applicable to meter tails and sub main cables , NOT to actual circuits ????

So, er you cannot make use of the diversity calculation for choice of protective device .....

Plse enlighten me if i m mistaken ....thanx.

There is whole host a circuit types that diversity can be offered to.
Table 1B in the on-site-guide will inform you on the circuits that can have diversty offered to them and the allowances.