cooker and induction hob urgent help URGENT ASAP

[flukey]

the rating of the cooker is 6.5kw, both items are connected to the same circuit but i will not be issuing any certs

you could have a bit of a problem if you refuse to issue certs for work completed. if you believe it to be unsafe you should have walked straight away imo

 

[Pinto Baz]

If the 6mm t&e cable is buried in a masonary wall as is usually the case in a house then that would be reference method C and it is rated at 46A. It the oven is a reasonable size, say 3kw for a built in oven that would give you a total load of 10.5kW = 46A. If you then apply the diversity for a cooker that gives you 10A + 30% of the remaining 36A (10.8A) + 5A for a integral socket would give you a total load equivalent to 25.8A so you should be ok. At the end of the day if you have a 6mm cable protected by a 32A breaker then you are not doing anything dangerous and if it keeps tripping then that is her problem, I would just connect it up and leave (preferabley with the bill paid). You could increase the breaker to 40A or even 45A provided that the volts drop and earth loop is ok, which it would be if the circuit is only 10m as you stated. I would prefer to put in a separate 4mm 32A hob circuit but I guess it is her choice.

 

[mars6394]

the t+e is just ran across the floor under the floor boards as it is a bungalow not clipped or anything as i could c as it was a original circuit already there,also not buried in plaster,the circuit is rated at 32amp breaker,i understand upgrading breaker to a 40 ma but do not like doing tht as if any problems do arise in the future then the 6mm is not protected as stated in the regs so i have not done that, i have been paid told her the risks of using the appliances on full load gave her quote for another circuit she didnt like price so i got money she owed me n have now left the job

 

[mechelec]

Diversity on a cooker is first 10A plus 30% of the rest, plus 5amp if there is a socket outlet on the isolator.

So on 32.61 A it is 10A +(0.3 x 22.61 =) 6.78A = 16.78A
with another 5A to add if there is a socket outlet.

Oops my mistake % and amps confusion

 

[Addlight]

On the subject of fitting an Induction Hob ...

Can anyone offer any advice on type of mcb to use with an induction hob please?

I've done the calcs for a new induction hob - all burners on max is 8.85Kw, so I've applied 80% factor for reference method B and come up with power of 11Kw, so In of 48A .

So a 50A mcb on 10.0mm2 should be fine ... but do these things have a high in rush current - if someone whacked all the burners full on together? Could that trip the B type mcb?

(This is new circuit on a dual RCD board, by the way).

Also, someone (can't see that screen now) said they use a 100DP as isolator - rather than SFCU? Is that okay? I'm looking through regs and OSG here, but can't see an obvious answer.

Thanks!

 

[KarlWilson3207]

Could someone help me with a little dilemma. I am looking at replacing my kitchen and switching from Gas to Electric. At the moment I have a Gas cooker which is hard wired into a cooker connection unit at the back of the cooker. Next to the CCU is a FCU (13A) above the worksuface is a cooker switch and 3 in socket. The circuit is protected with a 45A RCB.

My question is, if I connect an 8.2kw induction hob and a 3.2kw oven, what size cable should be used. I have worked out the diversity for the circuit and have got 26.9A (Could someone check that for me). Also could these simply be wired straight into the CCU?

Hope this all makes sense, my knowledge of Electric's is only basic and is based on what I have read in books. I have also heard that diverstiy calculations can not be applied to induction hobs, again can someone confirm this.

Thanks for your time guys

Karl

 

[telectrix]

you are on the right track. local isolation by means od a cooker switch is preferred to using the MCB at the CU for isolation, but as this work is notifiable to LABC, you need to either . 1. get a registered sparks in. 2. notify LABC and pay them a fortune. 3. get on with it at your own risk.

no.3 is not advised as you could put the lives of you and your family at risk.

 

[KarlWilson3207]

Thanks for the reply mate, dont worry, I have no intention of doing it myself was gonna get a spark in but just wanted an idea of what would need doing. So would that load be carried safely by 6mm or would it have to be 10mm? im not sure what is there at the moment

 

[telectrix]

IMO, the 6mm will be adequate unless it needs derating due to insulation. i would use a 40A MCB if no derating . just re-read your post. seen you have a cooker isolator. sounds a straightforward job.

 

[KarlWilson3207]

Yes, I thought it would be simple just wanted to make sure I wasn't missing anything obvious. If it wasn't notifiable I might have had a go myself

 

[telectrix]

hmm., if the cooker isolator and ccu are already in situ and capable of handling the new cooker, then all you would be doing is installing the cooker/hob. as you will not be altering the fixed wiring, then it's debatable whether it requires notification.

 

[KarlWilson3207]

Ah right, fair point, might save me a bit of money. Think the only "work" that would need doing is changing the current CCU to a twin CCU because im presuming that I would need a twin one.

 

[telectrix]

a twin one would be ideal, but it is easy enough to get 3 x 6mm into a single one. for a twin ccu, you would need a dual single back box (not as double back box)

 

[pushrod]

Hi Karl, don't know too much about induction hobs but manufacturers specs tend to take precedence on everything - check out the booklet or contact the manufacturer for any special conditions re diversity/installation

 

[Thomas123]

Does the cooker need a 32A supply as some are only on a 13A plugtop. If it does then you may be pushing it with the hob as well. Dont forget diversity as the OSG states the first 10% of the rated current plus 30% of the remainder of the rated current Plus 5A if a socket is incorporated in the Cooker CU

true you can take diversity into account, but... how often are you gonna have the oven and hob on all at once? quite a lot imho. sunday dinner... your easily going to have the oven on and all 4 hobs on..