Cooker and Electric Hob...

[dom_424]

Hi,

I have just bought a Stoves electric hob and oven, i have worked out the maximum running current will be about 35A (for both together), i have run 6mm2 cable inside the cavity wall, but i have just read that 6mm2 cable inside a cavity wall can only run at 32A??? Is this correct (see http://www.diydoctor.org.uk/projects/electriccables.htm). I based it on the fact the cable could do up to about 48A (shows what i know).

I am concerned now as i have already fitted the kitchen (i have never had an electric hob before). I have fitted a 42A fused spur and a cooker connection point by the cooker, was intending fitting both the hob and over to this, will i have to change my plans????

 

[martin43]

Hi Dom

but i have just read that 6mm2 cable inside a cavity wall can only run at 32A??? Is this correct

Fraid so, youll need 10mm sq.

I have fitted a 42A fused spur

Did you actually mean 42A? Have you fitted a cooker control unit, which you will need.

cooker connection point by the cooker, was intending fitting both the hob and over to this

Not good practice, better to connect the hob to the CCU and fit a FCU for the oven. What are the current demands individually for the oven and hob?

regards
Martin

 

[dom_424]

The oven is at 2375W @ 230V (10.2A) and the hob is 5750W @ 230V (25A). I can't run the cable through the wall now as it has been skimmed, can i conduit on the outside of the wall, or will i need to run in the wall and get it reskimmed.

Yes, it isn't a fuse spur, it is a cooker control unit @ 42A. Will the 6mm2 be okay for the hob @ 25A, then if i run 1.5mm2 for the oven @ 10.2A, should that suffice???

Just to check, would the diversity take into account for these not running at full load current...

 

[JohnD]

If you have a 6mm cooker cable protected by a 32A MCB, this is quite usual.

Because the heating elements in ovens and rings switch on and off thermostatically, it is very unlikely that you will ever be able to trip the breaker or overload the cable.

It is preferable to put the oven through its own 13A fuse with an FCU, otherwise the only fault protection would be a 32A MCB which is not at all close.

 

[dom_424]

Thanks for the help guys, appreciate it.

What is best to do then, should I run a spur to an FCU from the kitchen ring main (would this cable have to be in the wall??), then connect the oven to that, if it is safer, i will do that, i don't want to overload the 6mm2. Will 1.5mm2 be okay for the oven???

 

[whistler]

Hmmmmm ..... Kitchen electrics ...... I presume that you do know about Part P regs ?

 

[dom_424]

Yeah, only qualified electricians can add a spur to an exisiting ring main, or the work has to be signed off by a qualified person.

Can you run an FCU for an oven by extending then ring main in the kitchen, i don't think you are supposed to do that, bu the oven is only rated at 10.2A full load, so surely that is okay on a 13A ring???

 

[Steve]

Spur from the kitchen ring main for the FCU - this ought to be above the worktop, with a flex outlet below.

Then just have the hob on the 6mm² cable.

But it would be ok to have the 6mm² cable protected by a 32A MCB - this is normal, and if the cooker ever drew more than 32A, the MCB would blow before the wire overheated.

So you can actually have the oven on the FCU from the cooker circuit instead. It would need to be on its own 13A fuse anyway, I bet if you read the destructions, this is what it says, or words to this effect.

 

[securespark]

The best solution is to leave the 6mil in for the hob. BTW, you don't NEED a CCU. If you want a socket, fine, but you just need a DP switch within 2 or is it 2.5m (never remember!!) of the appliance (and not in a position where you have to reach over the appliance to turn the switch off...

If you can, I would be tempted to fit a 16A radial for the oven, as it will take a lot of strain off the ring, especially if there is no sep. circuit for the kitchen.

The more you spread the power used across a ring, the better.

Finally, are you sure the oven is only 10.2A? A single oven, I take it, with an interlocking switch that disallows two elements on together?

 

[dom_424]

I am pretty sure it said 2375W on the back, 2.3kW for the oven, 2.5kW for the grill (they can't be on at the same time), so that should equate to no more than 10.8A, i will check tonight though...

Thanks for all your help anyway guys, it has put my mind at rest...