Neff Hob and Oven

nkp · 7 Nov 2006

Hello. Same old question Im afraid but clarification would be welcome.
Replacing old electric Hob and fan oven with
Neff B1322.1 oven rated 2.8kW and
Neff T1323 hob rated 6600W (assume that is 6.6kW?).
Old set up was running off 30Amp fuse through a dedicated socket.....am I snookered with the new set-up?
Thanks in advance

davelx · 7 Nov 2006

If you take the two units together, ie, the same as a free-standing cooker (I'd say it is the same from a load point of view) and apply diversity, the load is 24.3A, assuming the cooker control unit has a 13A socket included, otherwise reduce by 5A. So 30A is OK for the protective device

There will be several opinions as to whether you should apply diversity here, I'm sure.

Then there is the question of cable rating & voltage drop - what is the cable size, how long is the run and how is it installed (clipped direct, in conduit, with other cables, etc?) oh - and what type of fuse, since there is quite a severe derate for rewireables.

nkp · 7 Nov 2006

Cooker control unit does indeed have a 13A socket.
Cable rating & voltage drop and cable size unknown as I am not qualified to judge.

Cable run is approx. 12M to box, in conduit in kitchen but not in loft space,

Thanks for your input davelx......

davelx · 7 Nov 2006

4mm cable would be OK from a voltage drop standpoint (5.2V at full load) but I think it's right on the edge for current carrying capacity even if the protection was an MCB, esp. if the cables are bunched up with others near the CU.

If the protection is a rewireable fuse then you need cable rated at 42A or more (ie Fuse/0.725), which means 10mm, I think - don't have the full tables to hand.

Time for the experts to comment, I think.....

Taylortwocities · 7 Nov 2006

Dont agree with your diversity calc. The 10A + 30% rule is guidance for a single appliance. Here you have two appliances so you calculate

(230V)

10A x 2 = 20.00
then add
30% of remainder = 6.26
plus 5A if you have an adopted socket = 5.00

Total 31.26amps

I'd lose that socket and just install a plain old (45Amp) switch

TTC

slippyr4 · 8 Nov 2006

Taylortwocities said:
I'd lose that socket and just install a plain old (45Amp) switch

TTC

But don't change to a 45A fuse - stick with the 30A

davelx · 8 Nov 2006

Taylortwocities said:
Dont agree with your diversity calc. The 10A + 30% rule is guidance for a single appliance. Here you have two appliances so you calculate

TTC

Yes, if you look at it like that. But why would you? The way an integrated hob and oven is used is no different from the way a separate oven and hob is used, so I see no reason to treat them differently.

Diversity is supposed to be applied with a knowledge of how the appliances on the circuit are used. You used the word "guidance" yourself - that's all it is.

Taylortwocities · 8 Nov 2006

Yes, true. But I just get that feeling that on Xmas Day morning someone might be suffering from cold turkey so I err on the side of caution.

TTC

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Neff Hob and Oven

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