Underfloor Cooker cable

lights-on · May 2, 2024

Hello All. I'm quite new to this game and gaining experience, but going well in the main.

My customer wants to feed a Hob ( on island in centre of kitchen ) and have the Oven separate on a wall unit. I'm running 10mm to give some headroom as induction hob involved, plus kettle and oven on same circuit so 40 amps not unlikely.

As I need to split the feed into 2, after the cooker switch, and want to avoid a junction box due to access for maintenance as it will be wall to wall cupboard units- therefore I want to go straight into the Cooker switch, then on to a twin Cooker outlet. This outlet will be behind the oven- but I'm considering taking the second feed ( for the island hob ) down a chase, then through a large-bore metal pipe across the ( already laid ) concrete floor, cutting a large channel in the insulation to give it space to emit heat.

To do this I need to pass the DPC + vertical plastic membrane on the bottom of the wall, then take a 90 degree turn into the pipe. Apart from protecting the 10mm down the wall with, say, a steel cover, does anyone reckon there's any problem with this? Picture attached - sorry was a sunny day today, but cooker outlet is visible in white chalk square.

Thanks in advance - as far as I can tell this is all kosher but it feels a bit wrong to be just taking the 10mm down the wall and around the bend. Maybe an elbow on the wall end to protect the junction would be best?

The other thing I'm less certain about, is coming out of the twin cooker outlet and then chasing one of the the 10mm cables back into the wall, for the island feed, rather than taking that cable out to an appliance which outlets would appear to be designed for.

Sorry, a few questions in there.

Thoughts would be appreciated.

[ElectriciansForums.net] Underfloor Cooker cable

littlespark · May 3, 2024

In this case, I’d have oven on hob on separate circuits.

Will there be room behind the kickboard, under the units to bring the cable out the wall in a sweeping bend?

Give it a good size of pipe or ducting for pulling through. 10mm is hard to get round a bend, looks like you’ll have 2.

Switch in the corner doesn’t look handy to get at in an emergency….. and you mention a kettle… shouldn’t it be a double box going in for a ccu with a socket?
A deep double box…

Is there framing and insulation going on that wall?

And one more thing…. What on earth is that wooden pole in the bottom right corner? It’s got a hairy foot on it??

lights-on · May 3, 2024

littlespark said:
In this case, I’d have oven on hob on separate circuits.

Will there be room behind the kickboard, under the units to bring the cable out the wall in a sweeping bend?

Give it a good size of pipe or ducting for pulling through. 10mm is hard to get round a bend, looks like you’ll have 2.

Switch in the corner doesn’t look handy to get at in an emergency….. and you mention a kettle… shouldn’t it be a double box going in for a ccu with a socket?
A deep double box…

Is there framing and insulation going on that wall?

And one more thing…. What on earth is that wooden pole in the bottom right corner? It’s got a hairy foot on it??

Thanks mate. Will ponder all this. Trouble is with separate circuits for oven and hob is having a junction box, which doesn't have a good place to live where it can be maintained- hence I'm using the cooker switch as a branch. This may be ill advise of me, as I'm not 100% I'm going to get the 2 x 10mm out the bottom of the back box, plus the feed from the top of the box. Trying a 47mm BB. The single back box in the corner was for the twin outlet and will be hidden behind the oven - the cooker switch will be on a double with a socket, to the right in the pic. The hairy foot thing- yes it's novel, not sure what its for....

westward10 · May 3, 2024

Why would separate circuits need a junction box?

littlespark · May 3, 2024

Some pre planning here would be good.

Get the actual specs of the hob.

I fitted two on two jobs just yesterday…. Turned out to be exactly the same hob.

Both were around the 7.3kW area… 32A, 4mm cables. Diversity means it’ll never pull that full 7.3

A separate circuit… I meant right back to the board…. But I know that’s not always practical.

Again, get the specs of oven as well. See if the existing circuit can take a hob and an oven, if you can use the existing.

One of the jobs I did above was existing cooker circuit for hob, plus 2x new 16A circuits for a 3kW oven and a 3.4kW combi microwave/ oven

Welchyboy1 · May 3, 2024

When you say plus kettle, does this indicate you are needing 13A socket/s on the island and a hob supply? and then an oven supply on a tall housing on the wall of the house?

First thing, whats the KW rating of the hob and the oven?

I would be inclined to run a seperate hob circuit to the island and hopefully locate an isolator in an island cupboard that can be accessed with reasonable ease and bring the ring circuit to the island also for general power for the kettle etc, I would use PVC hi impact conduit for this on the floor only, bringing it level from the floor to the DPC with prefab 90 bends at each end probably looking at 2x 25mm runs of conduit from wall positions to centre of island for ring and hob circuit

Looks like you still have the insulation and top screed to be laid to meet the top of the DPC so be quick and get it laid now before its installed, you shouldnt have to chisel any floor surface

Hopefully the hob will be 32A so a 6mm rather than a 10mm would be easier to work with

You dont say if the oven is single or double but for a single usually a single 2.5mm/16A circuit to 20A isolator located in the cupboard above the oven

I would loose the wall switch altogether

and forget about splitting a single cooker circuit for both

Just my opinion