I've recently put some outside lights on some smallish SWA. I'm happy with how it has gone but not having done this before, I would like to double check my armour earthing on the gland fittings. Is there a normal way to do this? I was thinking along the lines of checking resistance somehow but it's a single run of cable 15m long so how would I?
Checking my earthing on SWA
- Thread starter MisterBoy
- Start date
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The proper way, would be to use an Earth Loop Impedance tester. These check both that you have continuity and the value of the resistance/impedance.
If I have understood your question correctly:
I think you just need to measure the resistance between the armour itself and the earth connection to it - at both ends.
It should be all but zero Ohms.
I think you just need to measure the resistance between the armour itself and the earth connection to it - at both ends.
It should be all but zero Ohms.
I have 15m length with 3 boxes, so I think as you say I want to check that it's a good conductor from the last termination to the earth connection. But since the end is 15m from the supply, how can I physically do that as my multimeter obviously doesn't have 7.5m leads
I was thinking I could (temporarily!) connect the live to the earth terminal on the final box, then connect my multimeter to the live and earth connections at the the other end. I guess this tests the live at the same time - is this the sort of thing you meant?
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I have 15m length with 3 boxes, so I think as you say I want to check that it's a good conductor from the last termination to the earth connection. But since the end is 15m from the supply, how can I physically do that as my multimeter obviously doesn't have 7.5m leads
I was thinking I could (temporarily!) connect the live to the earth terminal on the final box, then connect my multimeter to the live and earth connections at the the other end. I guess this tests the live at the same time - is this the sort of thing you meant?
You could do that, but only an impedance tester checks to the 'quality' of the terminations will stand up to a load. Put simply - You can measure a good low resistance with an ordinary meter, but under fault conditions and some current - the resistance of the connections can suddenly increase.
That makes sense. I have my dad's kit but I'm not sure he had one of those - is it a specialist bit of kit? I can ask a pro to check it properly later, for now I just want to find obvious faults in case any of my mechanical gland fittings has an issue - I've given them all a good tug already.
A normal bit of an electrician's test kit.
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