S
sparks72
Hi
I hope this makes sense.
Went to look at a job a few days ago, did a quick test on the incomer of a 3 phase supply TNC-S system (seperate from the main consumer board) got a Ze of 0.19, all good, went to test the seperate consumer board & got a Ze of 0.33 & a Zs at a few RCBO protected sockets, the max being 1.80!
Went back a few days later & did the same test, Ze at incomer was 0.19 but Ze at property had shot up to 3.88!! did an IR test on mains cable & all good.
I added a new 25 mm earth conductor to the main incomer & the Ze at the property lowered to 0.22 & Ze at the RCBO sockets was a max of 0.68!
went back today & the Ze at the property board had gone up again to 0.31 & the Zs at the RCBO protected sockets had risen to a max of 1.77!
Had the LEB look into their side of the supply & got the all clear.
The cable from the main incomer to the property is a 25mm 2 core SWA using the steel wire as the earthing, the run from incomer to property is around 50 metres.
I think their is a split in the SWA sheathing. probable damage when installed 10 years ago (no certs)
has anyone else come across this & if so what was the problem.
Thanks.
I hope this makes sense.
Went to look at a job a few days ago, did a quick test on the incomer of a 3 phase supply TNC-S system (seperate from the main consumer board) got a Ze of 0.19, all good, went to test the seperate consumer board & got a Ze of 0.33 & a Zs at a few RCBO protected sockets, the max being 1.80!
Went back a few days later & did the same test, Ze at incomer was 0.19 but Ze at property had shot up to 3.88!! did an IR test on mains cable & all good.
I added a new 25 mm earth conductor to the main incomer & the Ze at the property lowered to 0.22 & Ze at the RCBO sockets was a max of 0.68!
went back today & the Ze at the property board had gone up again to 0.31 & the Zs at the RCBO protected sockets had risen to a max of 1.77!
Had the LEB look into their side of the supply & got the all clear.
The cable from the main incomer to the property is a 25mm 2 core SWA using the steel wire as the earthing, the run from incomer to property is around 50 metres.
I think their is a split in the SWA sheathing. probable damage when installed 10 years ago (no certs)
has anyone else come across this & if so what was the problem.
Thanks.
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