Armoured cabling questions

[DIYTom]

ive been looking at running armoured cable down my drive, well I fact two cables, one for lights and one for an electric gate. All the cables I've seen are not coloured as I'd expect. Three core is brown/black/grey. So assuming you still use brown as live would I use black as neutral? And what about the earth? Is the cable self earthing as it's (at least partially) buried, or would I use the grey for earth?

And with the lights cable what would be the best way to do it? My preferred method (less digging) is to run the cable in the bushes with three T junctions, then short Spurs from these Ts buried under the grass to the lampposts. Would that be acceptable (I'll use fully IP rated junction boxes).

 

[ericmark]

This question also came up in another post. It is better to over sleeve a black or a grey with green/yellow than to over sleeve green/yellow with grey or black so common to over sleeve either the grey or black with green/yellow and the other with blue.

I personally would not rely on an IP 68 box. All boxes could be IP rated may be IP11 but IP rating says what water and dust it will protect against and without those numbers or letters it means nothing. IPXXB or IP2X (X means any letter or number) would not be suitable.

As soon as you fit the gland the IP rating will depend how well that gland is fitted. Filling with re-enter-able compound or epoxy resin it the normal way. If there is no air then there is nothing to expand and contract and draw in water. Even petroleum jelly is better than air.

If under ground then all connections must be crimped of spring clip type no screw connections.

 

[Gutterball]

You only need to use 2 core the SWA is the CPC (earth).

 

[sparkwright]

You should use
Brown as live
Grey sleeved blue as neutral
Black sleeved green and yellow as earth

Better to use 3 core cable rather than 2 core.

By relying on the armour as the earth, there is a risk the armour could get damaged. Also if the sheath should get damaged, the armour could corrode.

However, you must make sure the armour is earthed.

 

[Spark123]

What are the power ratings of the lights and the gate? I'm wondering if you could get away with a single circuit and cable incorporating permanent live, switch live, neutral and earth?

 

[ban-all-sheds]

And what about the earth? Is the cable self earthing as it's (at least partially) buried

You really do not know enough to be installing SWA, and by extension I'm pretty sure that you don't know enough to be designing circuits either.

Please either put all thoughts of doing to one side until you know what you're doing, or if you can't wait, please get an electrician.

• 
  
  
  
• //www.diynot.com/wiki/Electrics:books
  
  
• //www.diynot.com/wiki/Electrics:MCBtoCable
  
  
• http://www.tlc-direct.co.uk/Book/4.3.1.htm (all subsections)
  
  
• http://www.tlc-direct.co.uk/Book/4.3.11.htm
  
  
• http://web.archive.org/web/20070327014113/http://www.kevinboone.com/cableselection_web.pdf
  
  
• http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html <- Specify 2-core cable and PVC, even if that is not what you are using or it will make invalid assumptions.
  
  
• http://www.tlc-direct.co.uk/Book/5.3.1.htm
  
  
• //www.diynot.com/wiki/Electrics:MCB2
  
  
• http://www.tlc-direct.co.uk/Book/7.13.3.htm
  
  
• http://www.tlc-direct.co.uk/Book/8.1.1.htm
  
  
• //www.diynot.com/wiki/Electrics:SWA_gland
  
  
• http://electrical.theiet.org/wiring-matters/16/elect-inst-outdoors.cfm?type=pdf
  
  
• //www.diynot.com/wiki/Electrics:Part-P
  
  The references above which are in italics are out of date. The principles are still valid, and you can absolutely learn valid things from them, but you will need to refer to the latest edition of the Wiring Regulations to get the correct data.

 

[flameport]

All the cables I've seen are not coloured as I'd expect. Three core is brown/black/grey.

Some 3 core SWA cables have those colours.
Others have brown, blue, green/yellow.

Generally it is better to buy cable with the correct colour cores, rather than oversleeve incorrect colours.

 

[JohnW2]

Some 3 core SWA cables have those colours. Others have brown, blue, green/yellow.

I think I've only ever seen the latter in 'sheds' - is it generally available from other sources?

Kind Regards, John

 

[ericmark]

Using SWA as an earth is all well and good when every year the ELI is tested and results logged and an eye kept for any trend showing likely cable faults.

With domestic the 10 years between each EICR means there can be a huge degrade without knowing and also often it's not tested every 10 years so having a copper earth as well as the SWA would seem to make sense.

 

[Lectrician]

Some 3 core SWA cables have those colours. Others have brown, blue, green/yellow.

I think I've only ever seen the latter in 'sheds' - is it generally available from other sources?

Kind Regards, John

I have seen wholesalers stock it for air con guys - pointless IMO, and far more expensive.

 

[ban-all-sheds]

A non-DIY shed supplier in Ireland.



Not sure why it's pointless.

 

[DIYTom]

Having read up it seems the colours in the three core SWA cable are that way so it's the same as three core and Earth. Makes sense in a way, but at the same time I would think most SWA cable is used in applications where brown/blue/green and yellow would be more use.

@Spark 123. I'm going to do two circuits. Bit more outlay for the cable but more flexible long term. I'm also planing to get a socket down on the gate post for occasional use of garden stuff, so I don't think the four core idea would be the best.

@banallsheds I'm not a moron thanks. Im having all the work checked by the sparky who's coming to install a new CU in the house and another in the garage. I'm just planing to save my self a not insignificant sum doing some of the hard labour. And thanks for all the broken links, they were of great help

 

[ban-all-sheds]

@banallsheds I'm not a moron thanks.

I never said you were - if you look again you'll see I gave you (or tried to) information because I have no reason whatsoever to believe that you couldn't understand any of it.

But the question you asked shows that you have no idea what SWA cable looks like, no idea about glanding it, or the different ways to earth it via the gland. Given that it did seem reasonable to think that your overall level of knowledge did not equip you for doing design work, or installing the cables.

Im having all the work checked by the sparky who's coming to install a new CU in the house and another in the garage.

Does he know that? He's in agreement?

What does "checked" mean with respect to signing an EIC for design and construction?

I'm just planing to save my self a not insignificant sum doing some of the hard labour.

That's fine, but if you want the work certified that can only be with his prior agreement and with whatever degree of direction and supervision he feels is necessary.

And thanks for all the broken links, they were of great help

Sorry about that - I knew that the archived Kevin Boone info was sometimes flaky - I had no idea the DIYNot Wiki links no longer worked.

I'll put them right.

 

[ban-all-sheds]

Broken Wiki links fixed. (Thanks for nothing DIYnot )

Kevin Boone one still to be resolved - sorry.

 

[Lectrician]

A non-DIY shed supplier in Ireland.



Not sure why it's pointless.

Because of the increased cost. I wouldn't pay more for it. That, IMO, is pointless. The AC guys have asked the wholesaler to stock it, again, IMO, pointless. Is the extra cost really justified?