Someone used SWA as main earth

[Jude_electricals]

Got called to a job where someone installed a 95mm 3 core SWA from the meter to a workshop about 120m away, then branched off to the main house and garage using 16mm tails. They're relying on the SWA armour as the main earth, but the terminations are sloppy and the ZE reads 0.75. The armour's cross section is too small for proper earthing at that length I figured a 50mm SWA would've been the right size but the customer refuses to upgrade the cable, so I'm stuck deciding whether to fix the terminations and see if the earth reading passes or recommend switching the buildings to TT systems. What's your take?

 

[prestigious-iceberg77]

Got called to a job where someone installed a 95mm 3 core SWA from the meter to a workshop about 120m away, then branched off to the main house and garage using 16mm tails. They're relying on the SWA armour as the main earth, but the terminations are sloppy and the ZE reads 0.75. The armour's cross section is too small for proper earthing at that length I figured a 50mm SWA would've been the right size but the customer refuses to upgrade the cable, so I'm stuck deciding whether to fix the terminations and see if the earth reading passes or recommend switching the buildings to TT systems. What's your take?

At 120m, that cross-section is way too small to give a reliable earth path, and a ZE of 0.75 is pushing it. Switching to TT might be the safest bet if the customer won't budge on upgrading the cable. Have you checked if improving the terminations would bring the reading down enough to pass?

 

[Chamberman04]

over 120m is way too much reliance on the armour, if the client won't upgrade the cable, I'd clean up the terminations first just to see what kind of improvement you get, but I wouldn't trust it to hold up for too long or.... maybe TT'ing the outbuildings might be your safest bet, less headache and you're not stuck trying to justify a borderline setup.

 

[truffle pig]

Im assuming that you are talking about the ZDB at the workshop / house rather than the ZE which would be at the incoming supply. I would TT at the workshop and use RCDs for your protection, otherwise I doubt you will get the reading low enough for whatever fuse protection you have at the head.