Heat-resistant cable for hob

[Rich5000]

First post, so be gentle

I’m swapping the hob in my flat from solid hotplate to induction. Both are AEG with similar power rating (7.2kW). My current hob (installed when the flat was built last year) is connected to the wall outlet using standard 6mm T&E, which from the posts on this forum seems to be standard practice. The instructions with the new hob say that “In the event of single-phase or two-phase connection, the appropriate mains cable of type H05BB-F Tmax90deg must be used”. I’ve gathered that this code means flexible heat-resistant cable (maybe BB is Butyl, but I’m not sure). I think the heat resistance may be advised as induction hobs do put out a fair amount of heat from underneath. I’ve searched the web for 6mm heat-resistant flex but had no luck. The nearest I could find was Butyl heat-resistant cable from TLC, but it’s only 4mm. Its listed rating is 35A, so in theory should be OK for 7.2kW, but I’m aware this might be a bit ambitious in an enclosed hot environment below the hob & above the oven. The cable length will be only 1m. So, finally (!) to my question. Is it safe to use this 4mm cable, or would you advise me to stick to standard 6mm T&E, use a larger T&E or keep searching for the elusive 6mm heat resistant cable?

Grateful for any advice.

 

[Softus]

Use two lengths of 4mm butyl-sheathed cable, wired in parallel.

 

[ColJack]

you checked the specs for air flow round that hob?
some require that you have an air gap at the front to allow air to circulate...

 

[Rich5000]

you checked the specs for air flow round that hob?
some require that you have an air gap at the front to allow air to circulate...

Yes, thanks. There's a 5mm gap between the worktop and the top of the oven control panel for the air to escape from the cooling fans.

 

[homespark]

Perhaps another case of manufacturers being out of step with actual installation procedures/materials? If they'd thermally insulated the underside more, then surely standard 6mm² T&E would have done...

 

[ban-all-sheds]

If Google is to be believed, H05BB cable in the UK exists only in the pages of installation manuals and DIY sites where people are asking "where can I get H05BB cable?".

Maybe it's another ploy by the manufacturers to create ways in which to wriggle out of warranties when products have not been installed according to the instructions.

How about using XLPE SWA, with the outer sheath and the armour removed?

 

[ColJack]

tri rated singles in metal adaptaflex?

 

[elektritek]

Butyl is rated to high temps so will be fine, 4mm Butyl rated at 35A will do as 7.2kW takes 31A @ 230V and then take diversity into account!

 

[ban-all-sheds]

H05RR?

 

[ColJack]

H05RR is 60 degrees i think..
H05BB is 90..

it's silicone rubber cable..

 

[Rich5000]

H05RR is 60 degrees i think..
H05BB is 90..

it's silicone rubber cable..

Thanks - finally I know what that code stands for. Now all I need to do is find a supplier for a 6mm version. Think I'll try AEG/Electrolux spares on Monday (though suspect they won't have it), or ask the company in your link.

 

[RF Lighting]

Having looked at the current carrying capacities for flexiable cables in BS7671, it only list upto 4.0mm²

I presume this means that 6.0mm² is not manufactured.

The only alternative I can think of is SY flex, but I'd imagine this would be special order from a wholesaler, and it is way over the top for your application.


As for the codes for flex, here you are:

 

[ban-all-sheds]

Doesn't list BB for jacket or insulation....

And since R can mean natural or synthetic rubber, and the quoted spec for the cable has an explicit temperature (Tmax90) rating added in, I wonder what BB actually means that is different to what RR can mean....

Is SY rated to 90°? I know that someone who lives near to me thinks that it's OK to use as buried cable, so maybe it's universally suited to any harsh environment you can find....