Garage electrics

[Chit]

Hi all,

I'm thinking of rewring the attached garage, I understand that this is notifiable work, but as I understand it, its's also something that anyone competent can do themselves as long as it is then checked by an electrician afterwards.

In order to have the inspection passed, what are the specific laws around rewiring a garage? Does the cable have to be protected within metal conduit at all or is it ok for it to be left as it is?

Does the cable also have to be armoured or can it be standard 2.5mm t&e?

Are there any other laws surrounding garage work?

 

[ban-all-sheds]

I'm thinking of rewring the attached garage, I understand that this is notifiable work,

Not necessarily - what exactly are you planning to do to the wiring, and why?

Have you read Schedule 4?

but as I understand it, its's also something that anyone competent can do themselves as long as it is then checked by an electrician afterwards.

It doesn't work like that.

If the work is notifiable, then you have to apply for Building Regulations in advance, pay the fee(s) and describe how you plan to ensure that the work will comply with P1.

Different councils have different procedures, and charging schemes, for how they deal with the inspection & testing of DIY work to confirm that it complies - you'll have to see what yours does.

But one thing you may not do, anywhere, is to simply DIY the work and then "get it checked by an electrician".

In order to have the inspection passed, what are the specific laws around rewiring a garage? Does the cable have to be protected within metal conduit at all or is it ok for it to be left as it is?

That depends on what the risks are of mechanical damage to the cables - only you can assess that.

Does the cable also have to be armoured or can it be standard 2.5mm t&e?

Ditto, but you'd never use SWA within the garage - if conditions are that harsh then steel conduit would be the way to go. Do you have a 20mm die for threading the ends, and a bending machine?

And how do you know that 2.5mm² is the right cable?

• http://www.tlc-direct.co.uk/Book/6.1.1.htm
  
  
• http://www.tlc-direct.co.uk/Book/6.2.1.htm
  
  
• //www.diynot.com/wiki/electrics:mcbtocable
  
  
• http://www.tlc-direct.co.uk/Book/4.3.1.htm
  
  
• http://web.archive.org/web/20080213151445/http://www.kevinboone.com/cableselection_web.pdf
  
  
• http://www.tlc-direct.co.uk/Book/5.3.1.htm
  
  
• http://www.tlc-direct.co.uk/Book/4.3.11.htm
  
  
• http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html
  
  
• http://www.tlc-direct.co.uk/Book/8.1.1.htm

Are there any other laws surrounding garage work?

You should read this: //www.diynot.com/wiki/electrics:part-p.

Other than that it's just a case of ensuring that the work you do is safe and competently done.

 

[Chit]

I'm looking to replace the electrics as there are literally only 2 plug points in the entire garage, both connected to a radial circuit. Everytime I need to use any power tools, I have to rummage around for extension cables etc and so I want to increase the number of plug points,

I also want to install a higher rated plug point for use with welding equipment which will run directly from the CU, through the wall (to which the CU is attached) directly into the garage, using a 6mm t&e cable.

The cabling sizes have been worked out using the following website:

http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html

Conditions in the garage are not really anywhere near that of damage to any cables. I do have both a tap and die set which I can use to thread condit and also a pipe bender which can be used to bend the conduit - but is it a legal requirement? At home, I'm more a general DIY'er and so the garage will be used as a small workshop, nothing industrial in any way at all.

I'm sure that this work is notifiable right?

 

[ban-all-sheds]

I'm looking to replace the electrics as there are literally only 2 plug points in the entire garage, both connected to a radial circuit. Everytime I need to use any power tools, I have to rummage around for extension cables etc and so I want to increase the number of plug points,

You can just add more - no need to replace the entire circuit. Adding more is not notifiable.

The sockets should be RCD protected.

You'll need to test for insulation resistance, continuity, fault loop impedance etc.

I also want to install a higher rated plug point for use with welding equipment which will run directly from the CU, through the wall (to which the CU is attached) directly into the garage, using a 6mm t&e cable.

A new circuit would be notifiable.

Conditions in the garage are not really anywhere near that of damage to any cables. I do have both a tap and die set which I can use to thread condit and also a pipe bender which can be used to bend the conduit - but is it a legal requirement?

No - doesn't sound like it's necessary.

But conduit and metalclad accessories look much better than surface clipped T/E, and you sound like the sort of person who'd enjoy doing that, so why not give it a go even if it's not strictly necessary?

BTW - if your bender is a plumbing one it won't have the right formers for 20mm conduit, and it might not be up to the job of bending steel.

I'm sure that this work is notifiable right?

The new circuit for the welder is.

 

[Chit]

I'm looking to replace the electrics as there are literally only 2 plug points in the entire garage, both connected to a radial circuit. Everytime I need to use any power tools, I have to rummage around for extension cables etc and so I want to increase the number of plug points,

You can just add more - no need to replace the entire circuit. Adding more is not notifiable.

The sockets should be RCD protected.

You'll need to test for insulation resistance, continuity, fault loop impedance etc.

I also want to install a higher rated plug point for use with welding equipment which will run directly from the CU, through the wall (to which the CU is attached) directly into the garage, using a 6mm t&e cable.

A new circuit would be notifiable.

Conditions in the garage are not really anywhere near that of damage to any cables. I do have both a tap and die set which I can use to thread condit and also a pipe bender which can be used to bend the conduit - but is it a legal requirement?

No - doesn't sound like it's necessary.

But conduit and metalclad accessories look much better than surface clipped T/E, and you sound like the sort of person who'd enjoy doing that, so why not give it a go even if it's not strictly necessary?

BTW - if your bender is a plumbing one it won't have the right formers for 20mm conduit, and it might not be up to the job of bending steel.

I'm sure that this work is notifiable right?

The new circuit for the welder is.

Now you've made me really want to put all the cabling in metal conduit !!!! - The pipe bender can handle metal pipes too but I'm not sure where I can buy these metal pipes from? I did consider just using some old copper pipes that I have laying around (the bender also can be used with copper piping) but the proplem here would be trying to get the cable inside the pipes once soldered in place ?

Which would be the more expensive option?

Also, using metal conduit to hold cable, I'm guessing it also needs to be earthed? Is running a 5mm earth cable directly from the earth block to this conduit sufficient or would it be easier and more economical to earth the conduit using the earth from within the t&e?

 

[flameport]

Also, using metal conduit to hold cable, I'm guessing it also needs to be earthed? Is running a 5mm earth cable directly from the earth block to this conduit sufficient or would it be easier and more economical to earth the conduit using the earth from within the t&e?

Good luck finding 5mm cable for sale anywhere.
The conduit is earthed at each socket/switch etc. as the earth wire would be connected to each one.

You wouldn't be using T&E in metal conduit, single insulated wires would be used.

You can't use copper pipe because there won't be any satisfactory way to fix it to the backboxes for the switches and sockets, and as you have already identified, no way of getting the wires inside it after fixing, plus it is a totally different size to electrical conduit.

Metal conduit and the fittings for it can be purchased from any electrical wholesaler.

A conduit bender looks like this:
http://www.toolbox.co.uk/hilmor-el25-steel-conduit-13457-73611
A hand held one designed for copper tubes will NOT be suitable.

 

[ban-all-sheds]

The conduit is earthed at each socket/switch etc. as the earth wire would be connected to each one.

Yo.

Chit - the conduit is coupled to a bush - the coupler and bush sandwich the wall of the metal accessory box - you'll have L/N/E singles in the conduit, you also take a flylead from the accessory earth terminal to the box.

.. and as you have already identified, no way of getting the wires inside it after fixing,

Shouldn't matter - you're not supposed to draw the cables in until it's all assembled...

A conduit bender looks like this:
http://www.toolbox.co.uk/hilmor-el25-steel-conduit-13457-73611
A hand held one designed for copper tubes will NOT be suitable.

Chit - if you don't have one, and don't want to get one, you might well be able to manage without, depends on the layout of your garage, what the walls are like etc, but you could possibly run galvanised trunking around the perimeter and just have straight drops, or a mix of drops & horizontal conduit runs between boxes.

 

[canduit]

Don't use copper, someone now, or in the future, may think its a disused water (or gas) pipe. Why not have a go with PVC conduit? Its fun, it allows room for error, looks nice, offers mechanical protection, and you can use a bender.

Edit: "and you can use a bender." Hopefully you know I mean a spring bender.

 

[JohnW2]

You can't use copper pipe because there won't be any satisfactory way to fix it to the backboxes for the switches and sockets, ...

You haven't lived A tank-coupler or copper-to-male coupler with a backnut does the job!

Kind Regards, John.

 

[Chit]

So many options.... !!!!

The pipe bender that I have works with metal pipes, but having said that, I don't want to go over the top with cost.

The only reason I wanted to use copper tubing was because I have a fair amount of it spare. But the idea about someone mistaking it for water pipes is also a very valid one.

I'm thinking that maybe the plastic conduit may well be the best idea....

Edit: "and you can use a bender." Hopefully you know I mean a spring bender.

I take it you mean a spring bender inside the plastic conduit and a bucket of boiling water/quick burst with a blow torch on the outside right?

 

[canduit]

Yes a spring bender inside the pipe; I've never tried the techniques you describe, but with the correct size spring and PVC at room temperature you shouldn't need to heat up. In my opinion its better to have a go with PVC first, then move on to steel conduit another time. Its a darn site cheaper too.

 

[seasickstevie]

You can weigh your spare copper pipe in to pay for all the conduit you'll need.

 

[JohnW2]

Don't use copper, someone now, or in the future, may think its a disused water (or gas) pipe.

Caution is never a bad idea but, in context, I think that risk is more hypothetical than real. We're talking about short lengths of pipe on a garage wall, the ends of which would be pretty obviously connected to electrical accessories. Anyone daft enough to be capable of thinking that this was disused water or gas pipe would probably be just as likely to think the same of galvanised steel, or even plastic, conduit

Kind Regards, John.

 

[canduit]

Fair comment John. Unless someone else is daft enough to run cables in copper pipe to their boiler, or hot water cylinder!

 

[ban-all-sheds]

Whats next fp cable because the pipes may get a little hot next to it??

No - Pyro.

Use bare 2 or 3H16 and nobody will be able to tell at a glance what's a cable and what's a CH pipe....