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All this talk about earth rods and I have one query.
When measuring an earth rod resistance and trying to get it down to 10 ohms are we talking about the rod resistance itself or are we talking about the EFLI?
If we are talking about the rod resistance being ten ohms then what about the impedance of the transformer rod which could be twenty ohms itself so no matter how low we get our earth rod resistance we are never going to get lower than the impedance of the transformer rod.
Admittedly there will be parallel paths involved through other peoples bonding etc but when talking about a low Ra are we talking just about the earth rod or are we talking about the total earth fault loop?
Thanks.
In theory, when we use an earth fault loop impedance tester, the instrument measures Ze because it gives us Ra for the earth electrode and earthing conductor, the resistance of the supply transformer electrode, the transformer winding impedance and the resistance of the supply line conductor from the transformer.