Installation of a new cooker hood extractor

[Gingerbadger]

Hi all,
Firstly, I apologise now for the level of detail I'm about to go into, but I really want to make sure I get this right and cover all aspects of the job.
Basically, I'm installing a new cooker hood extractor which will need to be certified but I have heard from at least one electrician saying that they are happy for me to do the bulk of the work to save money and they will come in to 'finish off'. Therefore, for obvious reasons, I want to make sure what I do is top notch and doesn't allow the electrician to try and take me for a ride and claim the work needs to be redone at great cost to me and profit to him!
The attached picture shows the current setup of the relevant part of our kitchen along with the proposed new setup.

Cooker Hood

• Gingerbadger
• 3 Jul 2013
• 1

Proposed Installation of a new cooker hood extractor

The proposed set up involves fitting a fused switch unit (with 3 Amp fuse) in to the mains circuit. I intend to lower the worktop sockets a bit while I'm at it and assume the FCU want's to be at the same level.
My biggest concern is regarding the connection of the cooker hood supplied cable to the FCU. I want to chase this cable into the wall and plaster over, but that would mean fitting the cooker hood before decorating, which I was hoping to avoid. Any ideas?
Think that's it. Any criticisms welcome!

 

[yorkspark]

Fit a flex outlet/single socket controlled by the fcu behind the chimney

 

[PrenticeBoyofDerry]

You will require to keep cable within the permitted safe zones as explained here:
//www.diynot.com/wiki/electrics:installation_techniques:walls.

Also chases within solid walls require to comply to part A of building regulations and the depths should be:
* Horizontal: No greater than 1/6th of the skin/leaf of wall (not the overall depth of wall including cavity).
* Vertical: No greater than 1/3rd of skin/leaf.

A flex plate behind appliance could be a reasonable solution, I try if possible to avoid this and route the flex of the appliance to the Switched FCU, so keeping all accessories easily accessible, but often this is unavoidable and accessories are fitted either at a higher level or behind the chimney of ex-fan.

 

[Gingerbadger]

Thanks for advice so far.

So, I've attached a follow up proposal. This one uses a flex outlet placed behind the cooker hood.

Untitled

• Gingerbadger
• 3 Jul 2013
• 1

As far as I can understand this arrangement conforms with the 'safe zones' too.
Two questions with this proposal though...
- What size cable should I use for the length between the FCU and the flex outlet? Do I need to stick with 2.5mm² mains cable?
- I know what is meant by a flex outlet, but can anyone point me in the direction of one? In particular at Toolstation, since its just down the road. They seem to have everything, but I can't seem to find one on their website!
Thanks again and keep your criticisms coming!

 

[ban-all-sheds]

So, I've attached a follow up proposal. This one uses a flex outlet placed behind the cooker hood.

Untitled

• Gingerbadger
• 3 Jul 2013
• 1

As far as I can understand this arrangement conforms with the 'safe zones' too.

I don't believe it does, because the flex outlet is hidden, and therefore there's no way anybody could be aware of the horizontal cable run.

- What size cable should I use for the length between the FCU and the flex outlet? Do I need to stick with 2.5mm² mains cable?

That you ask that shows that you obviously have no idea what protective devices are for, and yet you think you can do electrical design work.

Please get an electrician.

- I know what is meant by a flex outlet, but can anyone point me in the direction of one? In particular at Toolstation, since its just down the road. They seem to have everything, but I can't seem to find one on their website!

Maybe they don't sell them.

Thanks again and keep your criticisms coming!

I have heard from at least one electrician saying that they are happy for me to do the bulk of the work to save money and they will come in to 'finish off'.

1) You need to hear that from the electrician you are going to use.

2) Then you need to ask him all of the questions about design and construction, because you'll be wanting him to accept responsibility for them.

 

[Gingerbadger]

OK, so how about some actual helpful advice?
If you don't agree with what I'm thinking how about explaining what to do, rather than just telling me it's wrong!

 

[JohnW2]

Fit a flex outlet/single socket controlled by the fcu behind the chimney

You will require to keep cable within the permitted safe zones as explained here: ... A flex plate behind appliance could be a reasonable solution, I try if possible to avoid this ... but often this is unavoidable

... but, as BAS has asked, does an essentially 'concealed' (certainly not normally visible, I imagine) flex outlet actually create a safe zone? - common sense says that it shouldn't. Whatever, as BAS has also said, it will be down to the OP's electrician to decide what (s)he regards as acceptable.

Kind Regards, John

 

[JohnW2]

OK, so how about some actual helpful advice? If you don't agree with what I'm thinking how about explaining what to do, rather than just telling me it's wrong!

As you will have seen, the answers are not necessarily black and white, and it's the view of the electrician who you'll be asking to 'sign for it' that matters. People here might give you their opinions, only for you to subsequently find that your electrician does not regard it as acceptable.

In passing, why are you proposing taking the connection between the new FCU and the adjacent socket all the way down to floor level and then back up again? - there's nothing actually wrong with your proposal, but I wonder why not just connect directly (horizontally) from one to the other (you're going to have to chop that wall about a fair bit, anyway).

Kind Regards, John.

 

[ban-all-sheds]

OK, so how about some actual helpful advice?

OK.

• http://www.google.co.uk/search?q=electrical+circuits+101
  
  
• http://kevinboone.net/electricity.html
  
  
• http://web.archive.org/web/20080213151445/http://www.kevinboone.com/domesticinstallations.html
  
  
• //www.diynot.com/wiki/electrics:books
  
  
• //www.diynot.com/wiki/electrics
  
  

If you don't agree with what I'm thinking how about explaining what to do, rather than just telling me it's wrong!

My explanation of what to do is this, (and I'm not saying it to score points or anything):

When it comes to electrical work, you must, absolutely must have a full and genuine understanding of how it works, and what you are doing, and why.

Doing it on the basis of just following instructions to put-this-wire-in-that-hole but without truly knowing why is a very bad idea.

Even designing the circuit characteristics and choosing materials and installation details for this hood supply is not as trivial as you think it is and it involves knowing more than you think it does.

Asking questions here can be a useful part of a learning process, but they are not a substitute for proper structured studying. The key term there is "learning process" - you cannot learn all the things you need to know just by asking questions here. It isn't structured enough - it won't provide you with a way to progress where each step builds on what you learned before.

You can't carry out a job like this by asking whatever random questions happen to occur to you. You've already shown that you have some dodgy misconceptions - what if you get something wrong because you have no idea your knowledge is wrong? What if you miss something because you simply have no idea it even exists, and just don't realise you don't know it?