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I've just bought a new cooker. A range cooker with a 4 zone induction hob. According to the installation specs it's rated at 14.1 KW and it "works on 32A connection".
I've been to check inside the consumer unit. The cooker circuit has a 32A MCB and the cable is a 6 metre run of 6 core twin & earth (my guess 4mm) which is routed under the floorboards to the old cooker point. As the new cooker is a bit further away, I've added 5 metres of 6mm t&e (7 core).
I think that existing cable might be a bit on the thin side, but I don't want to go ripping up carpets and floorboards just yet, we've got enough going on at the moment with knocking down walls in the kitchen and re-fitting the bathroom.
How marginal/critical is my existing wiring and what/when should I think of replacing it?
Link to product page? 14.1kW doesn't sound right and would probably blow your main fuse, let alone trip the circuit breaker.
Here's the installation guide from Belling
My understanding is that cookers require a lower rated connection than the total suggests because everything isn't on at full blast at any one time. There's a fancy name for that which I've forgotten. EDIT -Diversity is what it's called- use 30% of the rated maximum, so they say.
because everything isn’t on at full blast at any one time.
...you've not seen my wife cook! 🙂
On my induction hob, the 'rings' are in part controlled / powered in pairs - so you can't have all 4 rings on at max at the same time. Across a pair, if I go above about 5 (on a scale up to 9) on one the other drops down to balance.
So even if each ring was say 5kw (made up number) I can't actually draw 20kw.
FWIW, we had a new range cooker with 5 zone induction hob installed last year and the electrician ran a 6mm cable to it from the consumer unit
(not actually into the consumer unit though, cos he discovered that there was a pool of water on the top of it from a leak in the porch roof. He, rather understandably, said we had to get that fixed first before he was touching anything else...)
I have an induction hob and cannot use I think 3 rings, maybe even 2 at full power. It flashes so effectively protects itself.
Doesn't affect cooking in any way, only need 2 or 3 rings at half power max.
Diversity for a cooker is taken as 10A + 30% full load of everything else, plus 5A if there's a socket on the cooker control switch (most don't have them these days).
Based on 14.1kw and 230V it's 14100W/230V = 61A
61A - 10A = 51A
51 x 30% = 15.3A
15.3 + 10A = 25.3A
That's the assumed current demand for the cooker, assuming no socket is incorporated, without any further, more informed info. It is a generic calculation and takes into account the fact that not all ovens/rings will be used, and even when many are used the simmer/oven stats mean they're not all pulling current at once.
14.1kW doesn’t sound right and would probably blow your main fuse
Would take a while, 61A on a 60 Amp fuse would probably never actually blow...
Even 100A load will take over an hour (BS1361).
Would take a while, 61A on a 60 Amp fuse would probably never actually blow…
I mean, you’re technically correct (the best kind of correct) but only if you assume that nothing else in the house is turned on…
The junction box halfway along the cable run makes me twitch. Perhaps wrongly as I am only an amateur electrician. same with using two different thickness of wire. I prefer to over than under spec but perhaps thats just my caution as an amateur. Personally I would run a new thicker cable right back to the consumer unit.
@creakingdoor Thanks for the confirmation. I'd seen that principle but not so clearly demonstrated.