Oh dear.....not quite accurate information here.
Good luck checking the resistance to earth of an earth stake using a multimeter.
The earth resistance test is a particular test requiring some very special instrumentation....how far from the earth stake are you pushing the multimeter lead into the ground? 2cm, 20cm. 2m??
Its a very a regulated and proscribed test carried out at specified intervals, usually for Standards compliance purposes and often on HV/LV substations, very rarely employed on a domestic install.
I think what you are referring to is the resistance from the earth bar in the CU to the earth stake. That can be checked with a multimeter, although in Oz these days the regulators require an impedance test not a resistance test. 2 ohms is still specified as ok.
Of course you still need to check the earth stake periodically as copper (wire) can and will corrode.
Consider installing RCD type devices that will trip out on current imbalance...even if your earth connection has failed. I wont discuss equipotential bonding at this point.
FYI RCD = Residual Current Device. They work on the principle of current flow out of the device and back in should be close to equal. If it is not then some portion of the current is going somewhere it shouldn't....possibly you.
20mA is a common standard these days.
You can get them combined with circuit breaker protection so they provide both people and cable protection. Don't forget to test them....push the test button every 6 months or so to make sure they work.
Pretty well mandated in Oz for both power and lighting circuits.
I believe I read something recently indicating something similar is now required by PEA for new installations.
This is literally an RCBO and exactly what I said I used. And here its typically adjustable up to 30mA.Originally Posted by mudcrab
"Residual current Circuit Breaker with Overcurrent protection"
Before you get spun off again, remember that Im American, You're from Oz, and a lot of this stuff is a type of UK standard, being marginally deployed in Thailand, and a lot of the technical wording can be different, but mean the same thing.
I wish I knew what you people are talking about, but I really don't. What should I know about my new house that I clearly do not. As you will appreciate, I am not at all handy or knowledgeable about these things. I just expect to move in and live normally.
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