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Topic Title: SWA
Topic Summary: use of incorrect glands
Created On: 12 July 2018 09:58 AM
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 12 July 2018 09:58 AM
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Ruggedscot

Posts: 6
Joined: 20 December 2017

So I notice that someone has installed a SWA cable this has been properly glanded at the supply side on the distribution board but it enters the equipment through a plastic packing gland. The wire armour is neatly taped up and the cable passes through the gland. The equipment is earthed via another cable and cross bonding, However I am looking to see if there is anything that would prohibit such an occurrence. Id have thought it should have been glanded at both ends. And if it had been difficult to gland some form of splitter box would have been used to facilitate a SWA gland being used.
 12 July 2018 10:23 AM
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mapj1

Posts: 10778
Joined: 22 July 2004

Not prohibited, but I'd only expect to see an insulating gland and armour sleeved at a transition between earthing zones - for example if the supply was from a TNC-s, and the load was a socket for a metal bodied caravan, and so it could not use the PME earth. Otherwise, it is more common to gland both ends, as this is part of the CPC, and helps to reduces the voltage rise at the load during an L_E fault.

-------------------------
regards Mike
 12 July 2018 10:36 AM
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dustydazzler

Posts: 2258
Joined: 19 January 2016

Originally posted by: Ruggedscot

So I notice that someone has installed a SWA cable this has been properly glanded at the supply side on the distribution board but it enters the equipment through a plastic packing gland. The wire armour is neatly taped up and the cable passes through the gland. The equipment is earthed via another cable and cross bonding, However I am looking to see if there is anything that would prohibit such an occurrence. Id have thought it should have been glanded at both ends. And if it had been difficult to gland some form of splitter box would have been used to facilitate a SWA gland being used.


Regularly come across this method now , especially where the swa is entering a plastic body enclosure or box.
I guess using a plastic stuffing gland makes life easier and puts less strain on the thin plastic body of the equipment or enclosure.
If the enclosure or box is metal I would always use a proper gland pack and banjo.
The old school on here would likely terminate the swa into a round conduit box then take a flexible into the plastic gland.
I like this method.
But its more expensive as you need to buy a conduit box.
 12 July 2018 11:12 AM
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tattyinengland

Posts: 1026
Joined: 23 November 2006

I would not ideally use a stuffing gland on the load side, but as long as the earthed armour is actually earthed at the DB side and the equipment gets its earth from an internal core of the SWA or perhaps even an additional earth (Properly sized to suit the circumstances) run parallel to the SWA, then I'd say its probably OK.

Not ideal but OK.

Kind Regards

Tatty
 12 July 2018 11:32 AM
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vstrom1000

Posts: 48
Joined: 09 July 2018

Under reg 543.1.1, SWA armour can be used as a cpc, and if the armours csa is insufficient, a separate cpc would be used, internal or external to the cable. However, if a separate cpc is used, the armour will need to be earthed because it's an exposed conductive part (GN8 2015). To ensure electrical continuity, gland tag washers, cpc and lugs should be used to bridge the gap between the armour and earthing terminal, to satisfy reg 543.2.2. This seems to suggest that continuity with the cpc/earth terminal and armour at one end would be sufficient if it's just to earth the armour as an exposed conductive part.
IET » Wiring and the regulations » SWA

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