Any advice from a qualified domestic sparky is much appreciated.
I’m an engineer with plenty of diagnostic experience inc electrical, just not IEEE qualified....!!
My house is served by a very unreliable underground mains cable (Western Power) that has caused loads of power outages over the years, several freezers defrosted while I’ve been away from home.
I noticed about a 6 months ago that my power was tripping more than my neighbours and also when there wasn’t a power outage.
I have two separate parts to the house, each having it’s own consumer unit but fed from the same meter. A couple of months back I located a Neutral to Ground fault and isolated it to one side of the house, after disconnecting the Neutrals one at a time from the consumer unit bus bar I found the faulty circuit. Next I disconnected the affected circuits neutral cables at sockets and junctions until I isolated the individual cable, then I found and fixed the fault. It was a Neutral conductor wire cut on the end of steel conduit.
I have just checked Neutral to Ground again and an insulation fault was back, this time far worse at just 0.5 Ohm, why hasn’t my power tripped I’m thinking.
Again I disconnected Neutrals but this time the the fault didn’t clear and I could not find an insulation fault on the house wiring with my meter.
The fault was only present with the 80A RCD ON so I switched off the RCD and disconnected the consumer unit ground busbar from the supply cable ground. Now I measured from the Neutral meter tail connection at 80A RCD in OFF position to the supply cable ground - still just 0.5 Ohms.
From what I can see the insulation fault is in the supply cable to the house or beyond which is why my RCD has not tripped.
Can somebody confirm my theory please?
Cheers
I’m an engineer with plenty of diagnostic experience inc electrical, just not IEEE qualified....!!
My house is served by a very unreliable underground mains cable (Western Power) that has caused loads of power outages over the years, several freezers defrosted while I’ve been away from home.
I noticed about a 6 months ago that my power was tripping more than my neighbours and also when there wasn’t a power outage.
I have two separate parts to the house, each having it’s own consumer unit but fed from the same meter. A couple of months back I located a Neutral to Ground fault and isolated it to one side of the house, after disconnecting the Neutrals one at a time from the consumer unit bus bar I found the faulty circuit. Next I disconnected the affected circuits neutral cables at sockets and junctions until I isolated the individual cable, then I found and fixed the fault. It was a Neutral conductor wire cut on the end of steel conduit.
I have just checked Neutral to Ground again and an insulation fault was back, this time far worse at just 0.5 Ohm, why hasn’t my power tripped I’m thinking.
Again I disconnected Neutrals but this time the the fault didn’t clear and I could not find an insulation fault on the house wiring with my meter.
The fault was only present with the 80A RCD ON so I switched off the RCD and disconnected the consumer unit ground busbar from the supply cable ground. Now I measured from the Neutral meter tail connection at 80A RCD in OFF position to the supply cable ground - still just 0.5 Ohms.
From what I can see the insulation fault is in the supply cable to the house or beyond which is why my RCD has not tripped.
Can somebody confirm my theory please?
Cheers
