Earthing the armour
- Thread starter Podooser
- Start date
No, one end, unless a single core SWA - which would never be installed in a domestic, and would have to be an aluminium armour!
You can earth at both ends if you like, but you MUST earth at least one end. (Best practice to earth it at the supply end if only doing one end)
The whole point of installing SWA (or concentric or split concentric for that matter) is so that if the cable is penetrated by something such as a spade, nail or anything else metal then it will contact the armour first before it hits the live wire.
This will automatically cause a dead short and will operate the OCPD or RCD supplying that circuit, removing the chance of electrocution.
If the armour is not earthed then any penetration which makes contact with the live wire will bring all the armouring live, and also the metal object which has penetrated the cable.
If this is a spade for example then this is not good and could well kill the spade weilder.
The whole point of installing SWA (or concentric or split concentric for that matter) is so that if the cable is penetrated by something such as a spade, nail or anything else metal then it will contact the armour first before it hits the live wire.
This will automatically cause a dead short and will operate the OCPD or RCD supplying that circuit, removing the chance of electrocution.
If the armour is not earthed then any penetration which makes contact with the live wire will bring all the armouring live, and also the metal object which has penetrated the cable.
If this is a spade for example then this is not good and could well kill the spade weilder.
Use a metal isolator, or terminate the SWA into an earthed metal enclosure such as an adaptable box, or as a last resort, if the plastic enclosure is strong enough to terminate the gland directly into then you can earth the gland using the banjo supplied in the gland pack.
How big is the SWA? Could you use split concentric cable instead?
How big is the SWA? Could you use split concentric cable instead?
You could use split con instead, which doesn't require any special glands, and can be terminated into straight into a plastic enclosure.
The last lot of 16.0mm² split con I bought worked out 30p a meter cheaper than SWA
http://www.diynot.com/wiki/electrics:concentric-type-cables-straight-concentric-and-split-concentric
The last lot of 16.0mm² split con I bought worked out 30p a meter cheaper than SWA
http://www.diynot.com/wiki/electrics:concentric-type-cables-straight-concentric-and-split-concentric
Just a standard adaptable box, probably 100mm x 100mm x 50mm.
Gland the SWA into the bottom of the adaptable box, and pass the cores straight into the switch fuse (I hope you meant to write switch fuse, not just an isolator). Then take a 10.0mm² earth from the earth terminal in the switch fuse, and bolt it to the hole in the SWA gland banjo.
Gland the SWA into the bottom of the adaptable box, and pass the cores straight into the switch fuse (I hope you meant to write switch fuse, not just an isolator). Then take a 10.0mm² earth from the earth terminal in the switch fuse, and bolt it to the hole in the SWA gland banjo.
Ooh yus - its earthed so that's a great place to earth the armour!
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RF Lighting said:
Not quite true for split...It may hit the neutral then the live?
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