help please - smeg 16kw oven

[kevineaton]

hi guys, i hope you are well.

got a question - i want to buy a smeg SY92IPX8. im not an electrician.

the manual says that it has a nominal requirement of 16kw (!)

to me thats 66 ish amps. (16000/240) from P=IV

i cant get a circuit breaker for a household consumer unit that big, and the cable for a 70 amp connection is enormous.

i have a 40 amp circuit to my current oven, and clearly thats not enough,. when i asked smeg, they said the following:

"You will need to have an electrician calculate diversity into the rating calculation before fitting"

which to me means that as long as you dont turn everything on at once, you might not burn your house down

is this correct? if so, how would anyone put it in their house?

thanks in advance

 

[Marvo]

Yeah, applying diversity is like applying common sense. Diversity works well when there's lots of items involved, for example if you go around your house and add up the current of every single electrical item it will probably come to considerably more current than you CU can supply. In real life you're never going to be running all these items simultaneously so you don't need a supply that's anywhere near that large.

Looking at the electrical specs I'd be tempted to connect it to your existing 32A supply. It will be possible to overload it if you run too many induction rings and the ovens simultaneously but for normal usage it will probably be fine. If you get frequent tripping problems you can always upgrade it to a 50A supply later.

 

[kevineaton]

thanks for that - but...what if i do use all the induction rings and ovens at once? i quite often use all 6 burners on my gas stove and the oven. the worst that can happen with gas is - well, they all dont work as hot as they should. with electrics, it could start a fire. that worries me.

however, if i was to upgrade to a 50amp breaker - would i have to change the cable from my consumer unit to the oven given that it currently (no pun intended) has a 40 amp breaker?

 

[Spoon]

If you go with marvo's suggestion of fitting it to the existing supply and you use every element on the oven it should just trip the 40A breaker. The cable should be sized for the 40A breaker so you shouldn't need to worry about a fire.
If you upgrade to a 50A breaker you may have to upgrade your cable. All depends on what size cable is in there currently.

 

[Marvo]

As Spoon says the circuit is protected against overload so it's not a fire hazard as long as it was correctly installed in the first place.

Connecting it to the existing supply won't cost you anything extra so it's worth a try. If it proves to be inadequate you're going to have to get a sparky in to assess the best way forward.

 

[telectrix]

AS PREVIOUS POSTS. BEASR IN MIND THAST EVEN IF YOU HAVE ALL RINGS AND OVEN SWITCHED ON, THEY WILL ALL BE SWITCHING IN AND OUT WITH THEIR THERMOSTATS, SO YOUR TOTAL LOAD AT ANT ON E TIME IS NOT LIKELY TO EXCEED 30a.

 

[kevineaton]

ok guys, thanks for that.

as far as i can make out, the largest fuse i can get for a consumer unit in the uk is 40 amps anyway - anyone know if thats correct?

(i wouldnt just up rate the fuse without getting a spark to check the cable its on though)

it would mean if i did need to up rate, then i would need a special consumer unit and a new cable just for the oven circuit>?

 

[telectrix]

you can get fuse/MCB up to 63A. this will never be needed. as i said, it's doubtful if your cooker will pull > 30A at any one time. the largest current will be if and when you switch all loads on from cold , together, but that's only a short term before stats start kicking in. the cable and it's protective device can handle this "start-up" current for short duration. worry not.

 

[kevineaton]

ok thanks guys. much appreciated. have a happy xmas!