Grid Switch For Ovens Advice

[leevis]

Hi
I am thinking about a grid switch solution for my new kitchen but need some clarification on what is needed, there will be among other things, 2 ovens, both 2.9kW, both hardwired and both will have their own circuit.

In my mind there will be an RCBO in the consumer unit, cable to the grid switch (a 20W DP switch) and then cable from this switch to the oven.

Would this be sufficient or would there need to be a fuse in there somewhere ie
Consumer unit > DP switch > fuse (in grid) > Oven

 

[ericmark]

I had a problem with a grid switch and an oven, new kitchen for 85 year old mother, and the council sent a trainer to show mother how to use oven and hob. And she told mother to switch off oven on the wall. It seems the trainer used gas, however when asked did she turn gas tap off, the answer was no.

So big question is when you turn the power off you loose the clock so oven will not now work until clock reset, so why turn the oven off? Yes a 20 amp switch can turn it off, but why? with a hob yes, to turn it off means with non induction hob it can't in error be turned on, but if an oven is turned on in error it only means a little wasted electricity it would not cause a fire, I would fit an isolator to a hob but not so sure about an oven.

My mother would not take my word not to turn oven off on the wall, had to get some one from council to tell her. And the RCBO also in kitchen at easy reach hight by the back door.

 

[BS3036]

@ericmark This time you forgot to mention that if you turn it off at the wall, the sleeve cooling function doesn't work so the cabinet can overheat. A genuine safety issue.

 

[leevis]

This is just for isolation, in real terms it will probably never be turned off (dont even know if there is a clock on it tbh). Just concerned about the fuse as its hard wired

 

[ericmark]

@ericmark This time you forgot to mention that if you turn it off at the wall, the sleeve cooling function doesn't work so the cabinet can overheat. A genuine safety issue.

Yes that was one of the main points.

This is just for isolation, in real terms it will probably never be turned off

I would agree, with ovens those made for Europe are often over 13 amp but under 16 amp, in the main it is considered 32 amp is a standard cooker feed, and as long as not over 32 amp there is no real need for a 13 amp fuse to an oven, in your case using a 20 amp isolator so the RCBO can't exceed 20 amp really.

 

[leevis]

So if I go 4mm Cable > 20A Grid Switch > 13A Fuse (in Grid) > Oven, is that the way to go?

 

[EFLImpudence]

If you mean one 32A/4mm² cable to both switches and ovens then - yes.

The 13A fuses aren't really necessary.

 

[EFLImpudence]

You say the grid switches are only for isolation, so all you really need for what you state is:

Two of:
16A RCBO > 1.5mm² cable (clipped to surface or buried in masonry) > cooker outlet > oven flex > oven.

Then you don't need the grid switches, the circuits can be isolated at the consumer unit.


Are you having a gas hob?

 

[leevis]

No gas, fully electric, there is an induction hob but that is somewhere else