what circuit breaker

[cjonsey]

I am changing my gas cooker to a dual fuel one so i have no wiring and have to start from scratch.I know that i start from the consumer unit then to the cooker control unit (45 amp ) then to a cooker connection unit (45amp) using 6mm wire (38 amp).The only quiery is what RCD/ciruit breaker do i use,the cooker is 4800 watts.Many thanks

 

[PrenticeBoyofDerry]

Firstly read the manufacturers recommendations as they should be followed.
If the information is not in the MI, then 4800W/230V would equal about 21A.
Apply diversity would bring below that, so a 20A 30mA RCBO, would protect for both overload and earth leakage.
Also you must if cable is buried follow the safe permitted zones.

PS.New circuits require notification to building control and I also recommend following the correct test procedures, to prove the circuit is safe to put in to services prior to commissioning the circuit.

 

[ericmark]

With portable appliances it is up to the manufacturer to fit what ever protection is required but with fixed the manufacturer can and does stipulate what the protection should be.

However the standard has been for many years 32 amp with a 30 ma RCD and 95% of instruction manuals will give those figures.

Personally I would use 10mm so it can be upgraded or better still twin 6 mm so it can be split at a latter date however this relies on good paperwork. If the cable is fitted to take 45 amp this needs to be recorded or in the future electricians will refuse to up the protective device as without paperwork it could have been 10 mm because of insulation in walls not to allow larger MCB in future.

 

[EFLImpudence]

Personally I would use 10mm so it can be upgraded or better still twin 6 mm so it can be split at a latter date

What happens if the future arrangements require the ovens on the other side of the room?

Shall we run cable to there just in case?

The world is short of copper.



For the OP - method C, 2.5mm² and 20A MCB is adequate.

The usual cooker circuit 6mm² (4mm² would do) and 32A MCB is good for 15kW (actually 19kW without integral switch)

 

[securespark]

The usual cooker circuit 6mm² (4mm² would do) and 32A MCB is good for 15kW (actually 19kW without integral switch)

Peut-être, Je suis fatigué.

I don't understand the bit in brackets.

 

[JohnW2]

The usual cooker circuit 6mm² (4mm² would do) and 32A MCB is good for 15kW (actually 19kW without integral switch)

Peut-être, Je suis fatigué. I don't understand the bit in brackets.

Peut-être 4mm² clipped direct is adequate for a 32A circuit (as in 4mm² radials - have you come across 6mm² ones?).

Kind Regards, John

 

[securespark]

What's the bit about the integral switch?

 

[ban-all-sheds]

I did wonder if he meant socket, but that only equates to just over 1kW....

 

[JohnW2]

What's the bit about the integral switch?

Oh, sorry, I was looking at the wrong 'bit in brackets'! I assumed that he meant integral socket – and, despite was BAS has written, EFLI got his sums right.

With no socket, diversity allows a 32A circuit to supply a cooker of about 19kW (about 83.3A) – total demand = 10A + (73.3A*0.3) = ~32A.

With a socket, diversity allows a 32A circuit to supply a cooker of about 15kW (about 65.2A) – total demand = 10A + (55.2A*0.3) + 5A = ~32A

Kind Regards, John

 

[securespark]

It all makes sense now.

Slap on the wristy to EFLI for elementary switch/socket confusion.

 

[EFLImpudence]

Sorry.

Slap on wrist duly enjoyed.

 

[JohnW2]

It all makes sense now. Slap on the wristy to EFLI for elementary switch/socket confusion.

At least he didn't call it a 'plug socket'

Kind Regards, John

 

[JohnW2]

I did wonder if he meant socket, but that only equates to just over 1kW....

It does - but, as I have illustrated, despite that EFLI got his diversity calculations right!

What you overlooked was that eating 5A into the 32A available total means that what is left for the cooker (before diversity) is reduced by 5A/0.3 = 16.7A = ~3.8kW.

Kind Regards, John

 

[ban-all-sheds]

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