people have died when their neutral return wire gets disconnected from the power pole ... I was wondering, if there's a way to stop this in anyone's house?
We are off the grid. Solves many problems, except a period of dark and cloudy days.
Integrity Tech Solutions @ Norsewood, New Zealand
I would have thought the house would also have an earth wire pegged into the ground - doesn't that provide the same protection?
However, our bach power went off recently and we could see that the earth wire to the power pole had broken off in a storm. The lines guy came out and repaired it, and commented that houses in the area tend to have poor earthing because the dry sandy soil is a poor conductor, and that therefore the house was in a risky state as it could have accumulated a dangerous charge.
it appears to be a result of no separate earth electrode and the pipework has been used as an earth substitute.
I suspect the water pipe feed into the house was replaced with plastic at some point, and bingo the pipework becomes live when this fault occurs...
"Standards Australia has issued a notice to alert tradespersons of a safety hazard involving the previous practice of using continuous, metallic water reticulation systems as an earthing medium rather than using the currently required method of earthing using an earth electrode."
it happens a lot more than you expect. and it may not even be your broken neutral causing the problem, it may be one of your neighbours with the broken neutral causing the problem
We had a stuffed neutral up a pole here for ages. I was always on low voltage here, with massive dimming of lights when starting up the circ saw etc. No shock problems that I know about unless the neighbours had problems with that.
They found it when changing the powerpole and power got much better afterwards. Since there was never a total outage nothing got reported.
I just had to get my fly in lead replaced due to a broken neutral. $1700 later :-(
Test showed impedance of 2.6 Ohms, when the legal limit was 0.4.
Pretty sure my return was going via my earth cable. Very dangerous....
Aredwood: This reminds me of another project that I need to do. A current monitor for the cable going to the earth stake. So I will get alerted to any neutral faults.
i'd be interested in the results of this project.
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@hio77 It will actually be a pretty easy project to make. Split core current transformer around the main earth cable (can be installed without needing to disconnect the earth cable). output into a amplifier/buffer, then peak detector/ latch circuit. And you would want to add a circuit that checks for under voltage and over voltage as well.
The fun part will be deciding what that circuit should then do once excessive current or incorrect voltage has been detected. Easiest would be to get it to switch off sensitive devices.
Another option is assuming you have a new switchboard, Get a sparkie to add a shunt trip device you your main switch, or a circuit breaker that feeds important circuits. So you can get your monitoring circuit to disconnect the power to the whole house, or the protected circuit.