Cooker cabling question

[STave]

Hi

My wife is looking at new cookers and has her eye on a giant range one that has a total load of 15.8KW!

I’m trying to get an idea of whether we need to add in the costs of a new supply to the consideration. The present supply is via a 32a Type B MCB to standard 6mm T&E PVC sheathed with a total run of 13.5m - of which 4m is plastered in conduit and 9.5m in ceiling/first floor void. The house was rewired about 12 years ago so consumer unit/earthing etc. is relatively modern.

Any views on whether this supply would be adequate for the giant cooker would be very welcome.

Thanks
Marcus

 

[londonboy]

No chance of using that existing cable.

More like a 10mm or even 16mm (off the top of my head) with a 50a mcb

 

[Steve]

It'll be ok with a 40 or 45A MCB and 10mm² cable.

Not sure on the calcs for 6mm on a 40A.

Although 15.8kw is 69 amps, you will be ok in reality with a 40A MCB*, because the cooker will rarely draw full load current (even with everything on, its all thermostatically controlled). Its called diversity, and is very useful.

Any chance of persuading her to use a gas hob? They are much, much better than any kind of electric hob, and far more efficient. Doing this would probably shave 10kw off your maximum demand.

*In fact in reality, you'd probably be ok with a 32A circuit, but this, IMO would be bad design, as you may well get niusance trips occasionally.

 

[chapeau]

Diversity is your friend....

Assuming worst case,

15800 / 230 = 69 Amps

For cookers, OSG, Appendix 1. Current demand to be assumed.

10Amps + ( 30% of remainder )

= 10 + ( ( 69- 10 ) * .3 )

= 28 Amps

Add 5 amps if you add a socket outlet which takes it to 33, so leave it out.

If rated 15.8kw at 240v then it works out at 27 amps + 5 amps = 32

So 32A/6mm sounds like it should be ok in the environment you describe (OSG appendix 6).

Though buy the book and work it out yourself to be sure. And I second the gas hob suggestion.....

 

[martinxxxxxx]

Yep chapeau is correct and I bet if you have a peep at the installation manual in the shop it will say 32A supply is what is required.


Martin

EDIT PS Gas hob or to my thinking a gas cooker would be better.

 

[Steve]

So 32A/6mm sounds like it should be ok in the environment you describe (OSG appendix 6).

I do think the guide for cooker diversity is extreme. Dont get me wrong, in cases like this its helpful, but I would put this appliance on a min 45A MCB.

 

[STave]

Thanks to all for taking the time to reply and for your helpful comments.

I agree entirely about the gas cookers - much better to cook with. The problem is that my wife is a firefighter and won't any kind of naked flame device in the house!

Regards
Marcus

 

[LoveRocket]

Thanks to all for taking the time to reply and for your helpful comments.

I agree entirely about the gas cookers - much better to cook with. The problem is that my wife is a firefighter and won't any kind of naked flame device in the house!

Regards
Marcus

No naked flames, but a cable carrying 69amps burried in walls and under floors?

PS. I know it will never actually draw 69amps, but maybe you could use this figure to persuade her to go for a gas hob.

 

[chapeau]

I suppose I would resist replacing a cable

with a total run of 13.5m - of which 4m is plastered in conduit and 9.5m in ceiling/first floor void

when an authoritative guide told me I didn't need to. I might have a different opinion if I was putting a kitchen extension in, even though my head would tell me this was a 'just in case' way of thinking

The problem is that my wife is a firefighter and won't any kind of naked flame device in the house!

Is this evidence based or 'just in case' ?