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Deleted member 26818
Different meters conduct RCD tests in different ways.
The most common, is to take current from the Line conductor and transfer it to the earth.
This is why many meters will not be able to perform the test at a point where there is no earth conductor.
The problem with testing at the end of the circuit, is that the tester will have to divert a greater amount of current, in order for the RCD to be able to detect the imbalance due to the resistance of the conductors.
30mA of current at the end of the circuit, could well be only 10mA or even as low as 5mA at the RCD.
You may have to divert 40mA or perhaps 60mA at the tester before 30mA is detected at the RCD.
The most common, is to take current from the Line conductor and transfer it to the earth.
This is why many meters will not be able to perform the test at a point where there is no earth conductor.
The problem with testing at the end of the circuit, is that the tester will have to divert a greater amount of current, in order for the RCD to be able to detect the imbalance due to the resistance of the conductors.
30mA of current at the end of the circuit, could well be only 10mA or even as low as 5mA at the RCD.
You may have to divert 40mA or perhaps 60mA at the tester before 30mA is detected at the RCD.
