Discuss Is this installation safe or not? in the UK Electrical Forum area at ElectriciansForums.net
And theres always the risk also of a meteorite strike as wellI guess Jamie's point is that if the cable were partially cut through, you could leave the line and part of the armour intact but sever the CPC, hence losing the earth connection to the armour and the sub DB without the circuit protection operating. Normally if the CPC is earthed at the source, you can't cut through all of the armour without hitting the line, so the protection will operate before the last of the CPC is broken. It's a far fetched scenario but it's needless because it's a bodge.
if the guy has got the SWA into the right hand CU through a hole, then there's no excuse for not fitting a gland.
Welcome back Glen.perhaps he wasn`t capable....
with a spade apparently.Other than the poor glanding this is being over complicated. How in the name of god are you going to damage a cable to the extent the CPC and the armourings are severed but the phases remain live?
Fit a feeder directional relay, should only cost a couple of grand + the pilot cable.
Crazy thread.
indeed dark...its what i was getting across at #9My take on it---
The Swa should be earthed correctly at the supply end it does not need to be earthed at the load end as you have a separate earth core.
If the cable suffers damage to the outer sheath then corrosion to the SWA has less likely chance of isolating the steel from earth also if the is damaged in your spade scenario nearer the supply side as oppose to the load side and it was glanded only at the load then zs values may not meet as the fault has to travel nearly full length to the load end gland then back down the earth core effectively doubling the distance... you can take a zs at the unglanded end down to the armour to see if it complies or not.
All in all their really isn't an excuse for not earthing both ends of the swa as this would be good practice although earthing at one end is acceptable and pref' the supply end which will ensure zs is met. Their is no reason why a section of the ceiling board couldn't be removed and made good after IMHO this is just lazy attitude and loose excuses.
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