Wiring for oven

[Mephi]

I am redoing the kitchen in the flat I recently purchased. Had an electrician over to redo some of the electrics but he couldn’t give me a clear answer as to what is required to replace the existing, free standing 50cm electric cooker with ceramic hob with 60cm single oven and induction hob. He even called up his office and I shared the specs of the new appliances i am planning on buying but they were unable or unwilling to give me a clear answer and said they’d have to come back for another visit. Needless to say I am unimpressed.
The induction hob I’m planning to buy has a fuse rating of 30amp, the oven 16amps.

As i am getting my new kitchen installed in a couple of weeks, I’m a but lost as to what the next steps need to be here before I have cabinets installed that’ll be covering the wiring.

 

[EFLImpudence]

If you have a standard 30A or 32A 'cooker' circuit then you can connect both the oven and hob to it.

They will be similar to the cooker you are removing.

 

[Murdochcat]

It’s a bit worrying that the “spark” that visited couldn’t answer if the oven and hob could be on the same circuit

 

[ericmark]

Normally a duel cooker connection plate is used

and both fed from the same 32 amp supply. An induction hob uses less power to a resistive hob, so the load will be reduced, so what's the problem?

 

[Harry Bloomfield]

Had an electrician over to redo some of the electrics but he couldn’t give me a clear answer as to what is required to replace the existing, free standing 50cm electric cooker with ceramic hob with 60cm single oven and induction hob. He even called up his office and I shared the specs of the new appliances i am planning on buying but they were unable or unwilling to give me a clear answer and said they’d have to come back for another visit. Needless to say I am unimpressed.

Are you sure he is even qualified?

 

[DetlefSchmitz]

Are you sure he is even qualified?

Definitely sounds a good question. Most real electricians at least have a strong opinion on the subject, even if it's wrong.

 

[securespark]

I believe a lot of newer sparks are unfamiliar with diversity, especially so when it comes to cooker circuits.

 

[Mephi]

Thanks everyone! I’ve got zero clue about these things but I didn’t like the fact that they were trying to book me for another visit without letting me know what needs to get done in the first place. Appreciate the help!

 

[Collectors]

Many hobs are around 6kw-25 amps ovens are max 3kw-12.5amps but quite likely 2kw-8.3amps so hopefully 37.5amps So if you have a 6mm TWE cable coming from the board with a 40amp fuse & on to a 45amp switch in the kitchen that switches an outlet below the worktops, at that point you want to fit a 45amp connection plate & spur off this with 6mm twe to a 13amp socket so you can fuse the oven down to 13 amp from the 40amp main fuse. If your hob is more than 6kw,? i would run another cable from the fuse board as it will be pushing things.

 

[Mephi]

The hob is 6.5kw with fuse rating 30amp
and the oven 3.5kw with fuse rating 16amp

 

[Collectors]

Your right on the boarder line at 41.66 amps. 6mm is rated at 41amps. I would run the hob only of the existing 6mm cable "if it is that?" & bring another 2.5twe cable in for the oven 14.54amps & put it on a 20amp fuse with 20 amp switches at the kitchen end "Not fused spurs".
Some might say you can take into consideration "Maximum diversity factor" that not everything will be on at the same time. It will be at Christmas.

 

[EFLImpudence]

Many hobs are around 6kw-25 amps ovens are max 3kw-12.5amps but quite likely 2kw-8.3amps so hopefully 37.5amps So if you have a 6mm TWE cable coming from the board with a 40amp fuse & on to a 45amp switch in the kitchen that switches an outlet below the worktops, at that point you want to fit a 45amp connection plate & spur off this with 6mm twe to a 13amp socket so you can fuse the oven down to 13 amp from the 40amp main fuse. If your hob is more than 6kw,? i would run another cable from the fuse board as it will be pushing things.

It doesn't work like that for cooking appliances.

Because of 'diversity' a 32A cooker circuit can supply upto 20kW of cooking appliances.

 

[RandomGrinch]

Some might say you can take into consideration "Maximum diversity factor" that not everything will be on at the same time. It will be at Christmas.

There is no reason not to apply diversity.
It's a proven method of specifying cable size and MCB.
Even if the devices could draw their maximum power - I.e. would the oven have its grill and fan oven on at the same time? - A 32A MCB would take around 15 minutes to trip with a 50A load.

 

[Harry Bloomfield]

It will be at Christmas.

No not even at Christmas!. Diversity still applies at Christmas, oven thermostats, and hot ring thermostats will still operate normally, even at Christmas.

 

[Collectors]

There is no reason not to apply diversity.
It's a proven method of specifying cable size and MCB.
Even if the devices could draw their maximum power - I.e. would the oven have its grill and fan oven on at the same time? - A 32A MCB would take around 15 minutes to trip with a 50A load.

I regularly have my grill & oven on at the same time. Best way to quickly brown things & get great roast potatoes.