The Australian wiring rules (AS/NZS3000:2000) introduced a standard relating to protection against indirect contact (Clause 2.3). Measuring fault loop impedence is mandatory to ensure the correct compliance of this clause.
If an appliance becomes faulty, the resistance in the earth return circuit must be sufficiently low enough to allow the safety switch or fuse within that circuit to activate before the voltage can increase causing injury or death.
What this means, is the test is necessary so as to show a technician that if there is a fault, the safety switch will operate within the specified time required under the standard.
How do we perform a fault loop impedence test?.
A fault loop impedence test is done between the active conductor and the earth. To test the loop impedance a technician will use an earth loop impedence tester which is plugged into the power socket (GPO) to take a reading.
At SafePower Safety Systems we use an earth loop impedence tester that will not trip out the circuits RCD that we are testing.
Testing of a power socket (GPO)
- Do a visual check on the socket to check for cracks or worn sockets or any indication of scorching
- Check the switch for any faults
- Perform the earth fault loop impedence test
- Record all results for the clients records