Kitchen Grid/Isolation switches

[Spinny]

Please can I get some advice on fitting grid/isolation switches into a kitchen. We did discuss this with our kitchen company and the plan is to fit the switches inside a suitable kitchen cupboard. So now I am wondering how exactly this is best done. The kitchen company have said the electrician should fit a surface box onto the backboard inside of the cupboard, which is a 3mm back board.

 

Is this the common approach and does anyone have any photos of this achieved in practice ?

Fitting an electrical box onto a 3mm board doesn't seem that robust, neither does it seem great aesthetically, a 47mm box would be 2 inches of box obstructing the back of the cupboard for example. It may be too late to do that much about it given the wires are in place. But what is normal, does anyone mount the box onto the wall behind the cabinet and then cut an opening around it ? Or reinforce the board from behind with timber ?

 

We have one wall run of cabinets with Oven, Microwave/oven, Warming Drawer, Induction Hob, Extractor Fan, fridge freezer, and a smart switch for opening the rooflight.

And a kitchen island with D/washer, wine cooler, quooker.

 

Would be really good to see photos of what others have done. I will discuss again with the sparky, but sometimes trades have no criteria other than quickest for them, whereas we will be living with it, and looking at it for 10-15 years.

 

[Russell griffiths]

If the wires are in place then that’s that, unless you want to move them. 
most of our isolation is in the pantry all flush fitted. 
however the isolation for the two oven is as you describe a 47mm surface box in the back corner of the cupboard. 
cut a square of osb and fit it behind the cupboard where the switch is going. 
47mm in a 600 deep cupboard isn’t exactly taking up a lot of room. 

[Nickfromwales]

1 hour ago, Spinny said:

Please can I get some advice on fitting grid/isolation switches into a kitchen. We did discuss this with our kitchen company and the plan is to fit the switches inside a suitable kitchen cupboard. So now I am wondering how exactly this is best done. The kitchen company have said the electrician should fit a surface box onto the backboard inside of the cupboard, which is a 3mm back board.

 

Is this the common approach and does anyone have any photos of this achieved in practice ?

Fitting an electrical box onto a 3mm board doesn't seem that robust, neither does it seem great aesthetically, a 47mm box would be 2 inches of box obstructing the back of the cupboard for example. It may be too late to do that much about it given the wires are in place. But what is normal, does anyone mount the box onto the wall behind the cabinet and then cut an opening around it ? Or reinforce the board from behind with timber ?

 

We have one wall run of cabinets with Oven, Microwave/oven, Warming Drawer, Induction Hob, Extractor Fan, fridge freezer, and a smart switch for opening the rooflight.

And a kitchen island with D/washer, wine cooler, quooker.

 

Would be really good to see photos of what others have done. I will discuss again with the sparky, but sometimes trades have no criteria other than quickest for them, whereas we will be living with it, and looking at it for 10-15 years.

 

Just DO NOT let them fit them down low, as you'll bash the crap out of them taking things in /out of the cupboard. Get then as high up as you can, plus then you pretty much cant see them.

 

1 hour ago, Spinny said:

Or reinforce the board from behind with timber ?

This. Install a piece of 15mm MDF or PLY behind, screwing it into place where the sockets etc will hide the screws.

 

One I did a few years back. Howdens kitchen. 
 

[Spinny]

I was kind of expecting that kitchen companies would have this nailed. If they are installing maybe 100 kitchens a year you would think they would have a neat, tidy, ultra aesthetic solution. I may be pedantic but I was expecting there would be some approach where we would end up with a neat labelled brushed steel grid switch flush with the back or side of the cupboard. 

 

Time to get the kitchen drawings out again. I think there is a 15mm service gap behind the cupboards. So by chiselling off some plaster I guess we might possibly get 33mm to recess most of a back box ?

 

[Mr Punter]

Sometimes I have had the sockets on a flex under the units.  Quite a few appliances have moulded plugs and it may be that any warranty can be voided if you cut them off.  It is not simple to anticipate what is needed.  I have had induction hobs needing hard wiring on a separate circuit where others are plug in 13A.

 

I like under cupboard lights to be switched from an extra gang on the main light switch, which can also be a challenge.

[Russell griffiths]

two switches for ovens, why make it any more complicated. 

[Nickfromwales]

3 hours ago, Spinny said:

Time to get the kitchen drawings out again. I think there is a 15mm service gap behind the cupboards. So by chiselling off some plaster I guess we might possibly get 33mm to recess most of a back box ?

You'll need 47mm for the cooker / hob cable  

[Spinny]

21 hours ago, Nickfromwales said:

You'll need 47mm for the cooker / hob cable  

Yes it is massive. The induction hob has mutiple boost zones on it = max 11 kw.

 

Unfortunately it is looking like the cables come out of the wall at the bottom of the cupboard position, so the switches will have to be behind whatever we put in the cupboard.

Don't suppose you can get smart home grid switch modules that you can turn off remotely ? Switch Bot maybe ?

[Russell griffiths]

42 minutes ago, Spinny said:

Yes it is massive. The induction hob has mutiple boost zones on it = max 11 kw.

 

Unfortunately it is looking like the cables come out of the wall at the bottom of the cupboard position, so the switches will have to be behind whatever we put in the cupboard.

Don't suppose you can get smart home grid switch modules that you can turn off remotely ? Switch Bot maybe ?

Why. 
how often do you need to isolate your induction hob ?

the day you buy a new one, that’s the only time you will ever go near that switch. 
put a surface mounted box in the corner and get moved onto the next problem. 

[-rick-]

19 minutes ago, Russell griffiths said:

Why. 
how often do you need to isolate your induction hob ? 

 

My flat came with a multigrid style switch on the wall with isolators for everything in the kitchen. I'm really surprised at how much I've used it. This probably isn't typical but for me it's come in handy a lot, especially my kitchen is coming to end of life and things are breaking. (I'm avoiding replacing things piecemeal and would rather either do it all at once or sell the place with the kitchen as 'in need of refurbishment').

 

Lot's of things break in ways that don't stop them working but are annoying to leave switched on. Timer module in oven is best example. Oven worked fine except timer, but with oven powered the timer made a constant buzzing. In this case I ended up fixing it when I replaced the oven fan but in the meantime it was very convenient to have an easily accessible switch.

[Nickfromwales]

1 hour ago, -rick- said:

 

My flat came with a multigrid style switch on the wall with isolators for everything in the kitchen. I'm really surprised at how much I've used it. This probably isn't typical but for me it's come in handy a lot, especially my kitchen is coming to end of life and things are breaking. (I'm avoiding replacing things piecemeal and would rather either do it all at once or sell the place with the kitchen as 'in need of refurbishment').

 

Lot's of things break in ways that don't stop them working but are annoying to leave switched on. Timer module in oven is best example. Oven worked fine except timer, but with oven powered the timer made a constant buzzing. In this case I ended up fixing it when I replaced the oven fan but in the meantime it was very convenient to have an easily accessible switch.

I think it would be less relevant in a brand new house with brand new appliances, where these things are maintained / replaced accordingly.

 

All hobs have standby buttons on them to switch them on / off tbh. That for me would be suffice. 

[-rick-]

Just now, Nickfromwales said:

I think it would be less relevant in a brand new house with brand new appliances, where these things are maintained / replaced accordingly.

 

This flat started as brand new as well. Everything ages.

 

I'm not sure that I'd ever agree that it's worth buying a brand new oven because the timer stopped working. The replacement part was £250 (may as well buy a new oven). In the end I fixed it for <50p and some solder but I'm not most people. 

 

Just now, Nickfromwales said:

All hobs have standby buttons on them to switch them on / off tbh. That for me would be suffice. 

 

Specifically about the hob I don't see any immediate need, my point was you don't know what you don't know. Having the ability to isolate has been useful to me in ways I wouldn't have predicted. That's all I'm saying.

 

I agree this is not an area for smart stuff though. (There are some clever uses of monitoring current draw of appliances in a smart house but switching on/off no).

[Spinny]

The main cable is 10mm. I am actually wondering whether this is sufficient - i.e. for an everything on scenario.

Hob 11kw, Oven 3kw, Mic Oven 3.6kw, Warming Drawer 0.8kw - Total 18.4kw or a massive 80Amps at 230V. Now the warming Drawer and the Mic could go on the ring main I guess but still leaves 14kw peak power, albeit only with all hob boost zones on - very unlikely but would still be 61A.

Fortunately I do have underfloor conduit coming up in that area.

Think I am going to have to question the sparky.

[-rick-]

16 minutes ago, Spinny said:

The main cable is 10mm. I am actually wondering whether this is sufficient - i.e. for an everything on scenario.

Hob 11kw, Oven 3kw, Mic Oven 3.6kw, Warming Drawer 0.8kw - Total 18.4kw or a massive 80Amps at 230V. Now the warming Drawer and the Mic could go on the ring main I guess but still leaves 14kw peak power, albeit only with all hob boost zones on - very unlikely but would still be 61A.

Fortunately I do have underfloor conduit coming up in that area.

Think I am going to have to question the sparky.

 

Firstly, I'm not an electrician, but from what I know electrians always apply diversity so don't calculate based on 'everything on'. Secondly, I wouldn't expect Microwave or warming drawer to be on the Oven circuit.

 

The Hob is the main thing that needs a dedicated connection. Wouldn't be surprised if everything else is intended to go on the ring main,

 

All these devices peak loads are way way higher than their continuous.

[Spinny]

OK, not sure what regs say about peak loads vs continuous ?

Not keen for a family Christmas meal to trip out the circuit.

 

[-rick-]

Been a while since I watched it and not 100% sure this is the video I'm thinking of but I think the below will explain this if you don't mind the presentation. From about 6:28 in if you want to skip the bit on cable size.