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Posted By Topic: Free standing oven and hob install

Jan 16 2019 08:12

Client has an old freestanding range on 6mm and is wanting to change it to a built in hob and oven. In the past iv usually just run existing 6mm straight to the hob and looped to the oven but sometimes is quite hard to fit a couple of 6mm wires into the hob connection block. Is there any type of junction box anyone uses that can be fitted behind everything?
Was also reading the standards and came across the position of the isolating switch. A lot of older houses have there range isolating switch mounted directly above the range itself. When changing the configuration of the range to a seperate oven/hob this would create an open cooking surface, therefore the isolating switch should really be moved to one side, 150mm from the edge of hob. Is that correct? Seems stupid considering it’s always been basically an open cooking surface and the isolating switch has always been there.

Jan 16 2019 08:25

Yes you can use a junction box behind the oven. Then you can use a 2.5mm2 to feed the oven, which usually has a smaller terminal block. Some ovens and hobs have a flex already connected, so the junction box is necessary anyway. The standard square ones are usually fine.

The switch position has been recommended " such a position that the user does not have to reach across the open cooking surface" for quite some time. But the "shall" requirement of 150mm to the side in 3000:2018 isn't mandatory as yet, however it would be best to move it now if possible.

Jan 16 2019 08:36

Thanks Doug. Yeah easier to just move the switch. And I’m never a fan of having smaller cable on a circuit that’s rated higher. I know the stove can’t physically draw anymore than 3.5kW but it never seems right putting it on a 32A breaker.
Even still, how do you get on with the junction box terminations? They would be impossible to terminate together because of there size.

Jan 16 2019 08:55

Ovens & hobs regularly come with smaller flex connected. No difference really. 1.5-2.5 on ovens, and 4mm2 on hobs. Some hobs also specify that the connecting cable is V105, so the standard TPS may not actually comply with their instructions.

And considering the normal unenclosed rating of 2.5mm2 is 30A+, I don't see why you would have a problem.

However, 3x6mm2 fit in standard single screw connector, so whatever floats your boat..

Jan 16 2019 11:53

being pedantic, the switch required for a hob (or other open cooking surface" is not required to be an isolating switch, and most of them - probably all in the domestic sector - are not. They are only functional switches, and that's all they need to be.