Quick Electrician question if I may

John

Moderator
Got a sparky coming out next week to quote on some work in my kitchen as it will be having a refit and leccy work is all notifiable these days.

Anyhow , Have got a new Induction Hob and Double Oven going in . Total rating 12.5Kw. These 2 items will replace an existing FreeStanding D/Oven&Hal hob total rating 10.9Kw.
This has its own connection on the CU with a 32Amp Rated MCB . Will it just be a case of disconnecting the freestanding cooker and connecting up the new kit , or am I looking at a new run from the CU :eek: not easy

Cheers

John
 

John Simon

Well-known Member
I am by no means an expert but I understand that kitcheny-shower type items need their own individual breaker so you may need an additional feed.
 

IronGiant

Moderator
A 9kW Unit should require 40 Amps, I'm assuming you have 40 Amp cable with the 32Amp circuitbreaker, so you are probably OK as it hasn't melted down. But it sounds like you may be underrated for your existing installation never mind a bigger one.

12.5kW would require 50Amps, so you need to check the rating of your existing cable at the very least. I know we were unable to install a 9kW shower because we only had 30 Amp cable so had to stick with 7kW.
 
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IronGiant

Moderator
Sounds like it to me, you probably need to put a new one in, in addition to what you have already, not even instead of. Sorry...
 
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John

Moderator
I thought as much . Have already looked round the usual DIY sites but some answers were not the clearest and others just turned into a bun fight over diversity and standards, Thought I would I know ask somewhere I know and can get the ban stick out if a bun fight ensued :rotfl:
 

niceguy235uk

Well-known Member
By the time diversity is taken into account, the total loading on the appliances wont be that much.

However, any spark worth his salt should install an additional circuit for the other cooking appliance.

If not, get a gas hob.

Diversity= Current = watts / voltage (230).

First 10A plus 30% of the remainder. If the cooker isolator has a socket outlet, then add 5A to the load.
 

John Simon

Well-known Member
I thought as much . Have already looked round the usual DIY sites but some answers were not the clearest and others just turned into a bun fight over diversity and standards, Thought I would I know ask somewhere I know and can get the ban stick out if a bun fight ensued :rotfl:

My Boss had the same issues - he ended up sticking with an all in one so he did'nt need the additional supply.
 

John

Moderator
Not really an option
 

John

Moderator
If not, get a gas hob.

My Boss had the same issues - he ended up sticking with an all in one so he did'nt need the additional supply.

Not really an option

The multi quote did not work for some reason .

And the cooker isolator does have a socket , would getting rid of that for a plugless one make any difference ? I am not adverse to having to run a new line . It'll just be bloody awkward is all
 

niceguy235uk

Well-known Member
And the cooker isolator does have a socket , would getting rid of that for a plugless one make any difference ? I am not adverse to having to run a new line . It'll just be bloody awkward is all

You will need to have a new circuit im afraid.

You can have 2 appliances running off one circuit, however, the one that you currently have installed more than likely, wont be rated high enough anyway.

So your best option (if i was doing the job), would be to install an additional circuit.

have a chat with your sparks when he comes round.

If its that much of a pig to do, make sure you are sat down when he gives you the quote.:rotfl:
 

John

Moderator
Thanks , I think .

Can you tell me if I am doing this wrong

The rating plates on the Oven & Hob show 4.9 - 5.3 for the oven and 7.2 for the hob . total 12.5Kw ( that bits right , taking the 2 highest numbers)
So that is 12500 watts . Divide that by 230 = 54.34 Amps . take 10amps off and then take 30% of that (13.3 amps ) + the 10 = 23.3 and the 5amps for the socket 28.3amps

Is that right ?
 

niceguy235uk

Well-known Member
Spot on.

Therefore, depending on length of run, it should be at LEAST at 6mm2 cable with a 32A MCB upfront.

Also, new regs are that any mods to circuits or any new circuits now require RCD protection up front.

So if you have an oldish CU then you may need that replacing as well.

Oh, and main earth bonding to gas and water supplies.

You just would not believe the hoops we now have to jump through, just to carry out even the smallest of works on an installation since the regs were updated last year.
 
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IronGiant

Moderator
You will need to have a new circuit im afraid.
.

So your best option (if i was doing the job), would be to install an additional



We already advised John to do that :)

Useless unprofessionals that we are ;)

Are we invisible? :rotfl:

If my simplistic 9000/230 = 40 amps and 12500/230 =50 amps was complete ******** it would have been helpful for all of us for you not to completely ignore it ;)
 
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niceguy235uk

Well-known Member
We already advised John to do that :)
No, you guessed.:D

Useless unprofessionals that we are ;)
You said it.;)

Are we invisible? :rotfl:
Sometimes:rolleyes:

If my simplistic 9000/230 = 40 amps and 12500/230 =50 amps was complete ******** it would have been helpful for all of us for you not to completely ignore it ;)
I didnt ignore it. You were talking complete ********, I just didnt acknowledge it.

If John did follow that, he would be contacting his electricity company for an additional 100A supply, just for the cooking appliances:rotfl:

Good effort though:thumbsup:
 

John

Moderator
So if I was to for-go the socket on the isolating switch . The 23.3 Amps of just the 2 Appliances on the 32Amp MCB would not be acceptable,is that not nearly a 30% buffer ?
Just want to understand a bit so I don't get baffled by waffle

Its a Wylex consumer with all MCBs and thankfully some blank banks
 

IronGiant

Moderator
Sorry for messing up your thread John, I think it is apparent Nice guy doesn't like me very much. I'll bow out.

Dave
 

niceguy235uk

Well-known Member
So if I was to for-go the socket on the isolating switch . The 23.3 Amps of just the 2 Appliances on the 32Amp MCB would not be acceptable,is that not nearly a 30% buffer ?
Just want to understand a bit so I don't get baffled by waffle

Its a Wylex consumer with all MCBs and thankfully some blank banks

John,

The diversity is calculated to aid the design of the circuit.

it is VERY rare that the full load of the appliance will be in use at any one time so we allow a percentage of the full load for the cale sizing and MCB rating.

So if you decide not to have a socket outlet on the isolator, then this gives more headroom for the cable.

it some circumstances the extra 5A for the socket can push the cable and MCB size up to 10mm and 40A respectively.

In your case, however, it will make no difference if you have the socket or not as the load will still be within a 32A MCB with the 6mm cable.

Now you know why electrical installation isnt as straight forward as some like to think.

Hope that makes sense and gives you a bit of ammo when your sparks visits you.

At least you will have some idea of what he is talking about.
:thumbsup:
 

John

Moderator
Well, I had a new 10mm feed fitted. He originally didn't think it would need it but after some calculations felt that whilst it would have been ok , the time that you needed it not to fail , with everything doing at full chat, it might. What fun that was. Across the ceiling , across the landing and down under the stairs. I think he was glad I stayed and helped him out with the routing
Anyhow, cost about £650 including all the shiney bits.
Induction hob is the way forward

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