Electric Hob

[too old to learn]

Hi,
I am wiring up a hob which has a total current rating of approx 32.5A (7800kw). However, the instructions say use 2.5mm cable, and the connection point is only suited to approx this size. seriously it would be difficult to squeeze 4mm cable in.
so i have bought some HO7BN4F 2.5mm cable (approx 1m length) as this is all i need from my socket outlet (internal cable all 6mm)
so is this cable all right taking into account of diversity?
I just think it is strange that they have not allowed enough clearance on the connections point to put in cable even upto 6mm if required. therefore not taking diversity into account?
thanks

 

[bongos]

Looking at the TLC website 2.5mm only allows a maximum current of 20A. Although you can allow for diversity when installing a hob, you would still have to make sure that the cable is protected by a 20A MCB. This may lead to nuisance tripping depending on how likely you are to have the hob on full power. I don't know the diversity figures off the top of my head but this is around 60% of the 32.5A maximum current you suggest.

The other option is to use the 4mm and this way you could use a 32A MCB and should avoid nuisance trips.

But if 4mm won't fit then I suppose you have only one choice

 

[too old to learn]

well as you say, the only choice i have really is that i have to use the 2.5 cable. I just cant believe a cooker manufacturer would not allow the option of installing thicker cable.
I will be getting their address and sending an email to them asking which of their design numpties came up with this option
Many Thanks

 

[BS3036]

With the diversity allowed in the On-Site-Guide, I make the current requirement 17.2A.

Edit:

Looking at the TLC website 2.5mm only allows a maximum current of 20A.

The page linked to says 25A, though.

 

[ban-all-sheds]

Unless you're desperately keen to have that particular hob, return it to the shop for a full refund on the grounds that it is not of merchantable quality.

OOI, what do the installation instructions say about cable size and circuit rating?

 

[too old to learn]

I cant remember exactly what is written, I think all it states in one box is power rating and cable, power rating it has 7800W and then under that it has 2.5mm. I can check and confirm later today if need be??
I did have look at the connection point as knew straight away it should be bigger cable if your not taking into consideration diversity, and as stated the gap is miniscule, will probs even struggle to get the 2.5mm in lol.
All i can think of is that I guess they have taking that you wont ever use all hobs at once for a long period of time?
After all, this is what most sparks would calculate anyhow, that is why diversity is there?
Seems a pain to me tho that there is the need to have 6mm installed and then right at the end it drops to 2.5mm.
I will be emailign the manufacturers for therre opinion on this and will report back what they say, if anybody is interested.

 

[TicklyT]

Could the designers originally have had a 2 or 3 phase supply in mind, as that is a common arrangement abroad?

The load would then be within the rating of 2.5mm conductors, being about 17 or 11 Amps per phase.