Cooker Circuit(s).

[EdwardCurrent]

Hello All.

Could I please have any advice on the installation of a 32A rated hob, with a 32A rated oven below.

The 'run' is 15 metres. Cabling will clipped direct, then embedded in plaster for the final 3 metres.

Taking into account diversity, adding both the cookers together would give me @46A, which is too close for comfort on a 6mm given the factors, so do you think that a 10mm T&E would be best installed from the C/U to isolator to dual oulet ??, but I have only seen dual appliance outlets rated to 45A ? (If I took diversity from the outlet plate I would have two appliances at @16.6A ??? )

As you can see I have well and truly confused myself on this one !!

Maybe 2 circuits will be the way to go !! Two isolators/outlets means more chasing and will look a tad pants ??

Thank you for your time,

Ed

 

[ColJack]

firstly, is this a single or double oven?
most single ovens are in the 15- 20A range.. where do you get the 32A from?
give us the wattage of it and we can work it out for you..

secondly, you don't do diversity on the outlet plate, if it's rated at 45A then that's it.. you can have 2 22.5A appliances on it..

thirdly, what kind of hob? some of the newer ones have a "boost" function that messes with the diversity..

and I'd whack 10mm in anyway regardless.. it's better to have a bit spare than just enough.. future proof it for yourself...

 

[wingcoax]

If you are running cable anyway go for 10sq mm as this will take almost anything in a domestic situation.

 

[EdwardCurrent]

Hello and thank you for the replies.

I have managed to find out the total 'load' for the cookers.

Hob = 7.2Kw
Oven = 5Kw

Do I add the total load up and do diversty calcs, or should I consider them as seperate ? (21A or 23A ?, not that the figure makes any difference here, but may in other circ's for future ref).

As per the installation I understand that both can have a common point of isolation, but am not entirely convinced that this is a good thing, however, the thought of two D/P isolators isn't sitting well with the customer.
How would you go about this ???

Thanks again,
Ed

 

[rebuke]

You convert to amps and do diversity separately, as they are separate appliances.

So, 7.2kW = 31.3A. First 10A + 30% of remainder is 16.4A
5kW = 21.7A. First 10A + 30% of remainder is 13.5A

Total load after diversity therefore 29.9A

(This is assuming the hob doesn't have what is often called boost functionality, as at that point the diversity isn't the same...

 

[EdwardCurrent]

Cheers Rebuke.

So a 32A MCB, 6mm cable run to an isolator, then onto a dual outlet plate is my answer ! (Although I will probably end up running a 10mm, as mentioned, for further users).
Would you consider the 'one point of isolation' for both appliances as poor design ? even if permitted.

Regards

Ed

 

[rebuke]

(Note I'm not a qualified spark, so don't necessarily rely on anything I say - no guarantees etc!)

Definitely run 10mm, the extra cost is minimal, and future proofs you.

Personally I'd have no issue with a single point of isolation - in my house I've got a hob and an oven, with a single isolation switch. There's an unswitched FCU for the oven (it only needs 13A), but that's behind a removable panel beneath the oven. Only thing to be careful of is how you connect them - ideally you want a dual outlet cooker connection point, but if you can't get one of those, then you could I guess have two connection points next to each other, although getting 2x10mm cables into a terminal could be rather tricky...

Oh, and obviously since this is in a kitchen it's notifiable to the LABC under Part P etc etc...

 

[ColJack]

if it was an all in one cooker, it would have a single point of isolation anyway so there's no problem there..