Discuss Is this installation safe or not? in the UK Electrical Forum area at ElectriciansForums.net

Just gland both ends and make the installation safe. Its not that difficult. Do the job better than the regs advise, that way I can sleep at night.
 
I 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.
And theres always the risk also of a meteorite strike as well
 
Heck, if you genuinely can't get an armoured gland on to anything, you could at least bodge it with an earth clamp (NOT suggesting this as good practice). Let's face it - you can't make it any worse.
 
It shouldn't have been done like that, but there's no way you're going to get a spade through a 5 core 16mm2 SWA cable to the point where the earth core is cut, even if you've eaten your spinach.

Now, if you've got a mechanical digger or something then maybe, but it's pretty safe from spade strikes IMO.

Besides, the mcb would trip from the short circuit.
 
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.
 
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.

Totally agree, even if the gland was hanging loose inside the containment area with a piranha nut or something and 16mm from there, just no excuse however you look at it. The only thing he seems to have got right is his choice of transport saving on fuel bills, he probably rides a horse.
 
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.
with a spade apparently.

Is the OP available for trenching work next time we've got a long cable run to dig in? Could do with someone with that sort of force behind the spade on the job.
 
My 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.
 
I think Darwood has summed it all up nicely!!

I too also support the glanding/earthing at both ends of a SWA cable, there's rarely any excuse not to in my opinion.
 
My 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.
indeed dark...its what i was getting across at #9
 

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