2.5mm or 4mm SWA Armoured Cable

[TheD]

I've got the new garage up and now I need to run a cable. I am thinking about running aromoured from the main house box to another box in the garage. I'll be running a lot of lights off it, A welder, bench drill, hands tools blah blah. The thing is I'm not sure if I should use 2.5 or 4mm.
All advice will be taken on board and used at a later date

[mas99]

You relly ought to work out the load and the distance and calculate it properly.

2.5 sounds too small for your needs.

[jeebus]

I would go for 4mm on a 32amp rcbo or maybe a 6mm on a 40amp, how far is the cable run going to be?

[TheD]

The run will be about 30m tops

[jeebus]

In that case a 6mm swa cable on a 40amp supply will be fine.

[TheD]

6mm on a 40amp it will be then. I thought 4 would have been loads but then if I knew that I wouldn't be asking

What should I fit for the garage fuse box then to suit the cable. Be running maybe 10 double sockets. About 6 fluorescent lights, a security light and an automatic opener.

[jeebus]

I would fit a small consumer unit in the garage like this http://www.screwfix.com/prods/99694/Electrical-Sup...

or you could get one without an rcd main switch and add rcbo's for individual circuits, or you could fit an rcd in the house consumer unit and just put something like this in which would be cheaper.
http://www.screwfix.com/prods/71988/Electrical-Sup...

[TheD]

Cheers Jeebus and the rest. Good advice

[King Herald]

The guy who signs off the part P cert will tell you whether it is too small or not I guess.

I used 6mm three phase SWA with mine, (far cheaper than the 'real' stuff) sleeved the ends to the correct colours, and into a Screwfix cheapie special. I ran the bulk of the wires myself, fitted the hardware, but my qualified sparkie nephew did the final wiring hookups, tests, and signed off the stuff.



One other bright idea I had was to bury 3 lengths of 20mm tube, with the SWA in case I ever want to run any other wires, heating, telephone out to the garage in the future. I've since run a hose through for compressed air, so not a bad idea.

Edited by King Herald on Monday 20th July 20:13

[TheD]

King Herald said:

The guy who signs off the part P cert will tell you whether it is too small or not I guess.

I used 6mm three phase SWA with mine, (far cheaper than the 'real' stuff) sleeved the ends to the correct colours, and into a Screwfix cheapie special. I ran the bulk of the wires myself, fitted the hardware, but my qualified sparkie nephew did the final wiring hookups, tests, and signed off the stuff.


One other bright idea I had was to bury 3 lengths of 20mm tube, with the SWA in case I ever want to run any other wires, heating, telephone out to the garage in the future. I've since run a hose through for compressed air, so not a bad idea.

Edited by King Herald on Monday 20th July 20:13

Cheers All info (pics especially )is great.

[jhfozzy]

King Herald said:

I used 6mm three phase SWA with mine, (far cheaper than the 'real' stuff) sleeved the ends to the correct colours, and into a Screwfix cheapie special. I ran the bulk of the wires myself, fitted the hardware, but my qualified sparkie nephew did the final wiring hookups, tests, and signed off the stuff.

I was going to do this too, but my sparky told me that I couldn't due to the regs. Could any any 17ths tell me if this is true?

I haven't bought the cable yet, so I still have time to get it and it is significantly cheaper for me to get the three phase cable via work versus the new single phase stuff.

ETA: Sorry for the thread hi-jack.

Edited by jhfozzy on Tuesday 21st July 09:41

[cjs]

jhfozzy said:

King Herald said:

I used 6mm three phase SWA with mine, (far cheaper than the 'real' stuff) sleeved the ends to the correct colours, and into a Screwfix cheapie special. I ran the bulk of the wires myself, fitted the hardware, but my qualified sparkie nephew did the final wiring hookups, tests, and signed off the stuff.

I was going to do this too, but my sparky told me that I couldn't due to the regs. Could any any 17ths tell me if this is true?

I haven't bought the cable yet, so I still have time to get it and it is significantly cheaper for me to get the three phase cable via work versus the new single phase stuff.

ETA: Sorry for the thread hi-jack.

Edited by jhfozzy on Tuesday 21st July 09:41

Just do it, who's going to know!

[Road2Ruin]

cjs said:

jhfozzy said:

King Herald said:

I used 6mm three phase SWA with mine, (far cheaper than the 'real' stuff) sleeved the ends to the correct colours, and into a Screwfix cheapie special. I ran the bulk of the wires myself, fitted the hardware, but my qualified sparkie nephew did the final wiring hookups, tests, and signed off the stuff.

I was going to do this too, but my sparky told me that I couldn't due to the regs. Could any any 17ths tell me if this is true?

I haven't bought the cable yet, so I still have time to get it and it is significantly cheaper for me to get the three phase cable via work versus the new single phase stuff.

ETA: Sorry for the thread hi-jack.

Edited by jhfozzy on Tuesday 21st July 09:41

Just do it, who's going to know!

The fire brigade when your garage goes up in smoke because you didnt do it properly.

[jhfozzy]

cjs said:

Just do it, who's going to know!

Any serious answers?

[Road2Ruin]

jhfozzy said:

cjs said:

Just do it, who's going to know!

Any serious answers?

It is s anotifiable job so you cant just do it. You can ru all the cable yourself if you want and think you know what you are doing but it will still have to be checked by a qualified electrician.

[cjs]

jhfozzy said:

cjs said:

Just do it, who's going to know!

Any serious answers?

That is a serious answer, do you know what you are doing re electrics? If so just do it yourself. If you don't then call an Electrician.

[King Herald]

jhfozzy said:

King Herald said:

I used 6mm three phase SWA with mine, (far cheaper than the 'real' stuff) sleeved the ends to the correct colours, and into a Screwfix cheapie special. I ran the bulk of the wires myself, fitted the hardware, but my qualified sparkie nephew did the final wiring hookups, tests, and signed off the stuff.

I was going to do this too, but my sparky told me that I couldn't due to the regs. Could any any 17ths tell me if this is true?

I haven't bought the cable yet, so I still have time to get it and it is significantly cheaper for me to get the three phase cable via work versus the new single phase stuff.

ETA: Sorry for the thread hi-jack.

The guy in the electrical shop told me it was okay, my Part P qualified electrician nephew (who runs his own electrical business) told me it was okay, several sparkys on the Screwfix electrical forum told me it was okay, and the part I read in the Part P regulations told me it was okay.

As long as the visible part of the core wire is coloured correctly you are okay, unless it has all changed in the last year or so.

Besides, running those three plastic electrical pipes was done just in case I did need to run another wire.

[jeebus]

King Herald said:

jhfozzy said:

King Herald said:

I used 6mm three phase SWA with mine, (far cheaper than the 'real' stuff) sleeved the ends to the correct colours, and into a Screwfix cheapie special. I ran the bulk of the wires myself, fitted the hardware, but my qualified sparkie nephew did the final wiring hookups, tests, and signed off the stuff.

I was going to do this too, but my sparky told me that I couldn't due to the regs. Could any any 17ths tell me if this is true?

I haven't bought the cable yet, so I still have time to get it and it is significantly cheaper for me to get the three phase cable via work versus the new single phase stuff.

ETA: Sorry for the thread hi-jack.

As long as the visible part of the core wire is coloured correctly you are okay, unless it has all changed in the last year or so.

That is correct, as long as the conductors are correctly identified then you are ok. Using 3 core cable is better as you don't have to rely on the armouring of the cable as an earth, you use one of the copper conductors instead and put some green/yellow tape on it.

[Ganglandboss]

King Herald said:

jhfozzy said:

King Herald said:

I used 6mm three phase SWA with mine, (far cheaper than the 'real' stuff) sleeved the ends to the correct colours, and into a Screwfix cheapie special. I ran the bulk of the wires myself, fitted the hardware, but my qualified sparkie nephew did the final wiring hookups, tests, and signed off the stuff.

I was going to do this too, but my sparky told me that I couldn't due to the regs. Could any any 17ths tell me if this is true?

I haven't bought the cable yet, so I still have time to get it and it is significantly cheaper for me to get the three phase cable via work versus the new single phase stuff.

ETA: Sorry for the thread hi-jack.

The guy in the electrical shop told me it was okay, my Part P qualified electrician nephew (who runs his own electrical business) told me it was okay, several sparkys on the Screwfix electrical forum told me it was okay, and the part I read in the Part P regulations told me it was okay.

As long as the visible part of the core wire is coloured correctly you are okay, unless it has all changed in the last year or so.

Besides, running those three plastic electrical pipes was done just in case I did need to run another wire.

Are we talking about installing yourself and getting it signed off or sleeving the cable? If it's the former, you've been told incorrectly. The only work an approved domestic installer can sign off is that what has been installed by himself or his firm. He could test it on behalf of you if you have been down the building control route where the building inspector has come out, checked your cable runs and told you to get it tested. It is very easy to get away with but it ain't legal!

If I was an approved domestic installer (I work for a consultancy now so I don't do any house bashing) I would not even contemplate signing off work as my own unless I had seen the job at every stage of the installation, knew the installer very well and had done a full test myself.

If it's sleeving the cable you are talking about that is perfectly acceptable. The only thing you need to watch out for is that you terminate the Circuit Protective Conductor (earth) properly. Most people will use the spare phase conductor as a CPC and sleeve it accordingly but neglect to earth the steel wires of the armoured cable. Buried cable has to have a concentric CPC; this means that if you hit the cable with a spade, you will hit something that is connected to earth first.

[King Herald]

Ganglandboss said:

Are we talking about installing yourself and getting it signed off or sleeving the cable? If it's the former, you've been told incorrectly. The only work an approved domestic installer can sign off is that what has been installed by himself or his firm. He could test it on behalf of you if you have been down the building control route where the building inspector has come out, checked your cable runs and told you to get it tested. It is very easy to get away with but it ain't legal!

If I was an approved domestic installer (I work for a consultancy now so I don't do any house bashing) I would not even contemplate signing off work as my own unless I had seen the job at every stage of the installation, knew the installer very well and had done a full test myself.

If it's sleeving the cable you are talking about that is perfectly acceptable. The only thing you need to watch out for is that you terminate the Circuit Protective Conductor (earth) properly. Most people will use the spare phase conductor as a CPC and sleeve it accordingly but neglect to earth the steel wires of the armoured cable. Buried cable has to have a concentric CPC; this means that if you hit the cable with a spade, you will hit something that is connected to earth first.

By 'running the wires' I mean I literally rolled them out and fastened them to the walls. I also mounted all the switches and lights etc, but my nephew actually connected all sockets, lights, fuse box, junction boxes etc to the wires. He also connected and tested the end in the house, both RCB's etc.

I did check with him beforehand to see which parts I was allowed to do, and which ones he had to do himself. Plus what materials, wire sizes I needed etc.

Edited by King Herald on Wednesday 22 July 13:30