What are the current regulations for RCDs?
In Australia, all commercial businesses and industrial facilities are required to maintain electrical safety, to remain compliant. One important component of electrical safety is the periodic testing of RCDs, to ensure they work correctly.
RCD testing requirements are in place to help the owner or managing agent maintain safety and compliance, these requirements are outlined is AS/NZS 3760, AS/NZS 3000 and AS/NZS 3017.
AS/NZS 3017 sets out common test methods to verify that testing of a low voltage electrical installation complies with the standard. The standard also includes minimum safety standards for test instruments. Testing must be carried out in such a manner that the safety of the operator, other people in the vicinity, and the test equipment is not placed at any risk. Essentially, it’s important during testing in an open area that either barricades are installed around the person testing, or a spotter is in place ensuring adequate distance is maintained around the tester. As RCD testing is usually done after hours, members of the public are not generally present, but it’s something that always needs to be carefully considered.
How do you test an RCD?
Clause 8.3 of AS3017 outlines suitable testing methods. All testing of RCDs must be done with power available to the RCD (live). Testing will interrupt the power supply to the circuit being tested for up to one minute. There are two aspects of RCD testing, covered by two separate testing procedures and are to be conducted as per below, aligning with AS/NZ 3760.
- Test 1: Integral trip push button test: at an interval applicable to the environment
- Test 2: Injection test: at an interval applicable to the environment
The integral trip push button test is a simple test and is relatively self-explanatory. This will interrupt power only momentarily. This test however cannot guarantee the RCD is operating correctly, thus the injection test is still required. The push button test only tests that the overall mechanical aspect of the RCD is operational, but will not check that it will work at the correct fault level in the event of an electrocution.
The injection test works applying various milli-amp currents using the tester, between active to earth. This test should be conducted to ensure compliance with AS/NZ3760.
The time taken for the active (and neutral) to be disconnected by the RCD is measured using the tester; this is what we are looking for, to determine if the RCD is tripping when it’s supposed to. The result of this test is recorded and compared to the framework of allowable outcomes. For a standard 30mA RCD a trip time of 300ms or less is classified as a PASS.
An RCD should not trip at less than 50% of their rated trip current, unless there is some other residual leakage current from an appliance or low insulation resistance.
The RCD under test should:
- not trip at half its rated trip current
- trip within 300ms at its rated current (30mA and 100 mA RCDs)
- trip within 40ms at its rated current (10mA RCDs)
- trip within 40ms at five times its rated trip current.
The AS/NZS 3760 stipulates that RCDs should be integral trip button tested every 6 months and injection tested every 12 months.
Prolux have the knowledge to undertake thorough RCD testing. For the safety of your building and its occupants call 1800 800 880 today.