Protection rating and cable sizing, oven & induction hob

[BR36]

Hi all, looking for some clarification on MCB and cable sizes I need to run for a new kitchen.

Cables will run through a combination of uninsulated platerboard ceiling, down the wall behind dot n dab plasterboard and in enclosed plaster where channels are repaired.

The online cable size calculators I've found don't show 'buried in plaster' as a criteria so is that considered more thermally insulated than say a stud wall or in an insulated cavity?

The oven is rated at 3.4kW - the MCB in the CU feeding the existing (same rating) is 32A and it looks like it's connected using 4mm cable (distance is about 6 metres. I'm assuming, as the original set up has been OK for years, the MCB and cable size are OK.

The new induction hob spec sheet says 'power load' 7.35kW and 'minimum power or fuse size = 32A'. It's been suggested it needs it's own supply and has to be 'hard wired'. So my questions are:

1) I've read somewhere that a diversity factor for the induction hob shouldn't be applied where the manufacturer states a specific load (i.e. 7.35kW and the minimum protection @ 32A), is that correct?

2) If 1) above isn't true, does the induction hob actually need to be on a separate supply from the CU or would an applied diversity factor mean the 32A existing supply and 4mm cable would be adequate for both oven and hob?

3) It's no hassle to run a dedicated supply for the hob so if I did so, given the cable routings I've listed above (distance also around 6m), will a 32A MCB in the CU and 6mm cable be OK (seems to be the size recommended in the online calculators unless in a heavily insulated environment) .

Really appreciate your anticipated feedback.

[Neelix]

Given you area diyer with no test kit I would suggest 2x 6 mm and leave the rest to a competent spark.

Who’s signing these circuits off ?

[BR36]

Given you area diyer with no test kit I would suggest 2x 6 mm and leave the rest to a competent spark.

Who’s signing these circuits off ?

Hi, thanks for the reply, a friend of my sister in law (qualified electrician) will sign it all off (he's done so on previous projects for me). The existing oven is on 4mm so I wasn't going to swap that unless it was considered a problem.

[Neelix]

Given you area diyer with no test kit I would suggest 2x 6 mm and leave the rest to a competent spark.

Who’s signing these circuits off ?

Hi, thanks for the reply, a friend of my sister in law (qualified electrician) will sign it all off (he's done so on previous projects for me). The existing oven is on 4mm so I wasn't going to swap that unless it was considered a problem.

I recommend you consult the spark signing it off ….

I’m a spark and never sign off 3rd party work

[etaf]

a friend of my sister in law (qualified electrician) will sign it all off (he's done so on previous projects for me).

probably best to ask the friend , as he/she should be signing off the design/installation/testing

[BR36]

Given you area diyer with no test kit I would suggest 2x 6 mm and leave the rest to a competent spark.

Who’s signing these circuits off ?

Hi, thanks for the reply, a friend of my sister in law (qualified electrician) will sign it all off (he's done so on previous projects for me). The existing oven is on 4mm so I wasn't going to swap that unless it was considered a problem.

I recommend you consult the spark signing it off ….

I’m a spark and never sign off 3rd party work

I will do , I guess it's a personal choice for signing off? When I spoke to building control they confirmed that (as I'd done previously) it was OK to DIY and get it signed of and notified by a registered spark