Socket Wiring, Horizontally or Under Floor

[matthew tubbs]

I am planning to do the wiring for my new kitchen extension. All my power sockets will be low level and run of a new ring circuit. Is it best for the cables to run:

a) From the socket downwards, under the floor insulation on to the next socket,
b) Out of the socket horizontally, behind the plasterboard to the next socket

I will be having 150mm of celotex with underfloor heating and liquid screed on top.

Thanks.

 

[bernardgreen]

Either way is acceptable provided the cables are all in "safe zones".

For a start http://i69.photobucket.com/albums/i62/RFLighting/safezones.jpg

then Google " safe zones for cables " to find explanations.

If the cables are in contact with thermal insulation then you will probably have to derate them. ( design for lower currents in the cables due to the increased cable temperature when thermally insulated )

WIll you be getting an electrician to wire and check the installation ?

 

[matthew tubbs]

Brilliant, thanks. The only place I cannot go horizontally is around the chimney breast as we have a wood burner so my plan is to chase upwards an go through the floor joists so I shouldn't need to derate these.

Absolutely, I plan to do the 'donkey work' and get a qualified electrician to sign it off according to building regs.

 

[matthew tubbs]

Another quick one - for my cooker hood is it a good idea to spur off the ring circuit and put a fused socket where the hood will be?

 

[John D v2.0]

Yes although the socket wouldn't be fused, the fuse is in the plug.
In that situation I'd just fit a fused connection unit and wire it directly to the hood, but either way is OK.

 

[EFLImpudence]

This is a case of the job NOT being DIY (do it yourself) in the sense that you have so little knowledge that you have to ask everything.

So, instead of employing an electrician to tell you what donkey work you can do, you are asking us to design your kitchen electrics step by step.


Employ the electrician now and ask him, then he will agree that it is done right and sign the paperwork.

 

[ban-all-sheds]

All my power sockets will be low level and run of a new ring circuit.

What design work did you do which led to the conclusion that a ring was the most appropriate circuit to use?

Absolutely, I plan to do the 'donkey work' and get a qualified electrician to sign it off according to building regs.

According to the Building Regulations it doesn't work like that.

Either you have it all actually done by an electrician, or you use a registered 3rd party certifier if you can find one, who you need to engage before you do any work, or you tell them that you will be doing the work and they tell you what they want you to do about inspection and testing.

The first, and most important question is:

When you applied for Building Regulations approval, what did you say, or what did you by default allow them to assume, would be the way you would ensure compliance with part P? Because if you told them one thing and then you do another, you could end up in a world of pain.

 

[John D v2.0]

As far as I know you don't need to do design to put in a ring, it's one of the standard circuits.
And building control aren't always the massive pedants you assume at first. The main thing is to satisfy yourself it's safe. Then work out how to satisfy building control.

 

[Doggit]

Now I know that you need to get the certifier to check what you are going to do first, but I think that as they are then going to test and certify the work that you've both agreed to, then it doesn't come under Building control notification. If you go the BC route, then in my area, they just pass the job over to the tester to make sure the works okay.

 

[ban-all-sheds]

As far as I know you don't need to do design to put in a ring, it's one of the standard circuits.

The question wasn't what should the design of the ring be, it was should a ring be the type of circuit to use.

And building control aren't always the massive pedants you assume at first.

If you tell them you're going to do ABC and they say "OK - that'll be fine", and then you go off and do XYZ instead they do have a tendency to get upset.

The main thing is to satisfy yourself it's safe. Then work out how to satisfy building control.

You have to sort out how you'll make sure it will be safe, and yes, then you work out how to satisfy them. And you do that by providing them with all the information they ask for, and then you wait until they say "OK - that'll be fine" before you start anything notifiable.

 

[ban-all-sheds]

Now I know that you need to get the certifier to check what you are going to do first, but I think that as they are then going to test and certify the work that you've both agreed to, then it doesn't come under Building control notification. If you go the BC route, then in my area, they just pass the job over to the tester to make sure the works okay.

He's building an extension, so BC are involved anyway. The electrical work is notifiable however it is done, but it depends on how it is done as to whether it gets notified in advance or after the fact. There are 3 options:

1. Registered electrician - notified after.
2. DIY/unregistered electrician + 3rd-party certifier - notified after.
3. DIY/unregistered electrician +ano form of inspection and testing as may be required by BC - notified in advance.

In effect 2) is just extending the approach of using an Approved Inspector for any notifiable building work to encompass electrics.

As he's had to submit a Building Regs approval request he'll have had to say which of 1/2/3 will be the method of ensuring compliance with Part P.

He'd be strongly advised to actually do what he said.

 

[John D v2.0]

To be honest we're building an extension and bc added a condition saying they needed a"part p" cert, so I replied saying I'm doing the work myself and it's not notifiable, at which point they were happy seemingly. I'll let you know what happens in the end, but I assume they'll be happy with a cert signed by me.

 

[matthew tubbs]

Thank you for all your responses, I respect your experience and advice.

Before my extension started my house was completely rewired by a respectable company. To answer your question about why a ring circuit was chosen - because this is what was recommended to me by this company. They have started the ring for the extension to and from the consumer unit and have committed to come back and certify it once the ring is complete, BC have been involved the whole time and are happy with this.

I am on a steep learning curve and recognise many electricians have already forgotten more than I know, but I will continue to learn and ask for help along the way.

 

[ban-all-sheds]

To be honest we're building an extension and bc added a condition saying they needed a"part p" cert, so I replied saying I'm doing the work myself and it's not notifiable, at which point they were happy seemingly. I'll let you know what happens in the end, but I assume they'll be happy with a cert signed by me.

I suppose we shouldn't be surprised that (some) LABCs contain numpties who don't understand the regulations just like (some) members of the public don't.

Part P doesn't only apply to notifiable work, it applies to any work whatsoever on fixed electrical cables or fixed electrical equipment located on the consumer’s side of the electricity supply meter which operate at low or extra-low voltage and are—
(a) in or attached to a dwelling;
(b) in the common parts of a building serving one or more dwellings, but excluding power supplies to lifts;
(c) in a building that receives its electricity from a source located within or shared with a dwelling; or
(d) in a garden or in or on land associated with a building where the electricity is from a source located within or shared with a dwelling.

Even if the work you're doing is non-notifiable, it is still mandatory for it to comply with the Building Regulations, so if your LABC are going to issue you with a completion certificate at the end to say that the extension complies, then they're going to be certifying that every single aspect complies.

So they ought to be ensuring that the electrical work complies with Part P.

 

[bernardgreen]

So they ought to be ensuring that the electrical work complies with Part P.

and that the installation is designed and installed in a manner which will make it safe to use and to maintain. Compliance with BS7671 for the design and installation goes a long way to ensuring the installation will be safe.