Kitchen wiring and back boxes

[Uncle_slow_pints]

Hi.

I'm in the process of installing a new kitchen and want to save some money by chasing walls etc and setting in back boxes for new ring main before I do the plastering.

3 questions if I may.

1 - The back box for the cooker supply. I understand the norm is to use a 47mm deep box but I'm cautious that this will be very deep in a breeze block wall. It's in the external wall so don't want to knock through into the cavity but don't want a massive box on the wall. The cooker will be in a tall unit. I would rather hide the isolator in there but I understand it's not best practice.

2 - The gas hob will be installed on the opposite wall on a "peninsular", essentially an island and therefore not on a solid wall. My plan is to have an isolator on the wall supplying a 3 pin outlet for the hob (the electric supply for the hob has a plug attached) but where to place the socket as I understand it should be on the "building fabric"

3 - Are there any issues running the power for the new ring and cooker down the wall behind the cooker?

Thanks in advance.

 

[wundaboy]

1. Bear in mind the depth of plaster and tile that will go onto the wall as the final finish, around 20-25mm combined, and factor that in when you're chasing for your back boxes. The most controllable and neat way I've found of chasing out box cavities is with an SDS chisel and scutch combs.

2. Socket should ideally be on/in the wall (building fabric), it's not terribly good practice to have it screwed to the unit but not the end of the world. Sometimes needs must!

3. I wouldn't run behind the cooker as there can't be an electrical accessory directly behind the cooker to show that the cable is there. Remember safe zones - cables should run directly vertical or horizontal to/from any switch/socket. Cables should never be run anywhere you wouldn't expect to find them.

 

[phatboy]

Your electrician will let you know if they are happy with a socket in a cabinet to serve the hob.... you need the electrician on-side with your plans now.... they certainly cannot sign off the design part of the job if you have chased, fitted boxes and then plastered as they cannot even see the routes.

47mm into 100mm block is fine, and you'd need to be VERY heavy handed to knock all the way through, unless you had very soft blocks.

 

[EFLImpudence]

The work is notifiable to the Local Authority - which you must do before you start the work OR employ a registered electrician who is willing to supervise your work.

 

[securespark]

There are plenty of cooker switches/ CCU's that are suitable for a 35mm box. But the front plate will be thicker.

 

[winston1]

Hi.

I'm in the process of installing a new kitchen and want to save some money by chasing walls etc and setting in back boxes for new ring main before I do the plastering.

3 questions if I may.

1 - The back box for the cooker supply. I understand the norm is to use a 47mm deep box but I'm cautious that this will be very deep in a breeze block wall. It's in the external wall so don't want to knock through into the cavity but don't want a massive box on the wall. The cooker will be in a tall unit. I would rather hide the isolator in there but I understand it's not best practice.

2 - The gas hob will be installed on the opposite wall on a "peninsular", essentially an island and therefore not on a solid wall. My plan is to have an isolator on the wall supplying a 3 pin outlet for the hob (the electric supply for the hob has a plug attached) but where to place the socket as I understand it should be on the "building fabric"

3 - Are there any issues running the power for the new ring and cooker down the wall behind the cooker?

Thanks in advance.

1. Can't see why it needs to be 47mm deep. Both the outlet plate and switch can use 25mm boxes. You don't actually need to have an isolator switch anyway.
2. As above you don't need an isolator. Pulling the plug is the best isolation possible. As it's a gos hob presumably the only electrics are the igniter and oven lamp.
3. Does not sound good to me. Think heat.

 

[phatboy]

1. Can't see why it needs to be 47mm deep. Both the outlet plate and switch can use 25mm boxes. You don't actually need to have an isolator switch anyway.
2. As above you don't need an isolator. Pulling the plug is the best isolation possible. As it's a gos hob presumably the only electrics are the igniter and oven lamp.
3. Does not sound good to me. Think heat.

Did you mean 25mm, or 35mm? 25mm is a pain for anything but simple light switches!

Local isolation isn't essential, but I'd generally consider it to be 'a good idea'

 

[winston1]

Did you mean 25mm, or 35mm? 25mm is a pain for anything but simple light switches!

Local isolation isn't essential, but I'd generally consider it to be 'a good idea'

No I meant 25mm. Light switches only need 15mm back boxes except for some fancy electronic types.

 

[Uncle_slow_pints]

Excellent, thanks for all the replies people, really fast response so I'll be using this forum more I think.

I was going to get the electrician to run the cables etc, then I'll plaster them in. The reason for wanting to run cables behind the cooker unit is that there will be a gaping hole in the plaster there already as a wall is coming down. But, if it's best to run them elsewhere than I can easily do that. The issue is the house is ex-council with concrete floors so all the electrical supplies for downstairs come from above. It's easy enough to drop it down the wall above the cooker isolator, I was just trying to avoid unnecessary wall chasing.

I've used a scutch to fit the other back boxes and it was money well spent. Always used a standard chisel in the past.

 

[Risteard]

It's worth noting before taking Winston's advice too seriously that he's not actually an Electrician.

 

[DetlefSchmitz]

It's worth noting before taking Winston's advice too seriously that he's not actually an Electrician.

I was going to write a long response to this, but in the event I couldn't be bothered to waste my time on 'Winston'.
My main point is that the problem isn't that he is not an electrician (to my mind that is irrelevant). He is just that he talks such utter nonsense most of the time.

 

[winston1]

Examples.

 

[phatboy]

No I meant 25mm. Light switches only need 15mm back boxes except for some fancy electronic types.

I guess from behind a keyboard that may seem accurate, but in the real world it's complete nonsense. The most basic dimmer requires 25mm, most sockets require 35mm if the wiring enters via the bottom.

Are we still being asked to report winston when he posts lies?

 

[winston1]

I guess from behind a keyboard that may seem accurate, but in the real world it's complete nonsense. The most basic dimmer requires 25mm, most sockets require 35mm if the wiring enters via the bottom.

This is what I wrote: "I meant 25mm. Light switches only need 15mm back boxes except for some fancy electronic types."

I have fitted many sockets with bottom entry wiring in 25mm back boxes over the last 43 years (since I bought my first house in 1976).
I have also fitted dimmers in 15mm back boxes. But anyway I consider dimmers as fancy electronic types.

 

[Risteard]

I was going to write a long response to this, but in the event I couldn't be bothered to waste my time on 'Winston'.
My main point is that the problem isn't that he is not an electrician (to my mind that is irrelevant). He is just that he talks such utter nonsense most of the time.

Indeed, but my point was simply that his bizarre claims aren't actually backed by real world industry experience. Many (such as @JohnW2) have much to offer this forum despite not being Electricians.