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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Electrical Questions >> SWA Cable to Garden Lights. https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1161002807 Message started by DIYFreak on Oct 16^th, 2006, 1:46pm

Title: SWA Cable to Garden Lights.
Post by DIYFreak on Oct 16^th, 2006, 1:46pm

I've run some 2.5mm SWA out for garden lights. I chose 3 core, using the black as earth, because as an amateur sparky I wanted to absolutely sure of earth contunuity. and didn't want to rely on the armour. I've heard anyway that the armour degrades and loses its conductivity over time.

I'm fitting SWA glands and shrouds for entry into the weatherproof plastic JB's at each end. I'm assuming I don't need to worry about an earth tag (drilling through the box, inserting bolt for earth connection and reducing the IP rating of the box in the process), nor piranha earth nuts, given that I'm using one of the conductors as earth. Is that right?

Pretty sure I know the answer but I'm a cautious sort of bloke.

Title: Re: SWA Cable to Garden Lights.
Post by UltraSpark on Oct 16^th, 2006, 2:31pm

When a core within the SWA is is being used as the cpc the armour is considered as an exposed conductive part and must be earthed.

Title: Re: SWA Cable to Garden Lights.
Post by sparkyjonny on Oct 17^th, 2006, 7:11am

Technically, it depends on how it's terminated - if the armour has been cut back before it enters the enclosure, there's insulation & sheathing between it & the live cores, so it's not an exposed-cond-part.

Despite that however, you should always earth the armour to provide automatic disconnection should the cable be cut through. The pirannha nuts will save drilling a seperate hole for a brass bolt.

Title: Re: SWA Cable to Garden Lights.
Post by UltraSpark on Oct 17^th, 2006, 10:26am

if the armour has been cut back before it enters the enclosure, there's insulation & sheathing between it & the live cores, so it's not an exposed-cond-part.

(I dont know how to use the quote function)

I dont dissagree with what your saying but could you explain for my own understanding how you are terminating the SWA with the steel wire strands cut back (the armour) how do you terminate the gland. What gland are you using?

Cheers

Title: Re: SWA Cable to Garden Lights.
Post by DIYFreak on Oct 17^th, 2006, 10:43am

Many thanks for all the helpful comments. I'll earth the armour to be on the safe side.

As I've already got the earth tags supplied with the glands I'll just go with the drill hole and bolt option.

Title: Re: SWA Cable to Garden Lights.
Post by Lectrician on Oct 17^th, 2006, 3:49pm

The armour is there to provide additional mechanical protection, but must also be earthed to provide protection against penetration of things like nails/spades etc. The spade will make contact with EARTHED armour before it hits the live conductor..........operating the OPD.

Title: Re: SWA Cable to Garden Lights.
Post by sparkyjonny on Oct 17^th, 2006, 9:16pm

wrote on Oct 17^th, 2006, 10:26am:

I dont dissagree with what your saying but could you explain for my own understanding how you are terminating the SWA with the steel wire strands cut back (the armour) how do you terminate the gland. What gland are you using?

Cheers

Via a stuffing gland. Sorry - just realised all terminations will be outside so not a good idea. I was thinking about within a building, where a gland is often used at one end, and the armour cut back before it enters the enclosure then taped up at the other end (think CU in shed or garage).

Title: Re: SWA Cable to Garden Lights.
Post by UltraSpark on Oct 17^th, 2006, 9:24pm

Hi Sparkyjonny,

I understand ya :-D

Cheers

Title: Re: SWA Cable to Garden Lights.
Post by sparkyjonny on Oct 17^th, 2006, 9:30pm

Glad someone does mate! ;)