RCDs are recognised as providing additional protection against electrocution in the event of failure of other measures of protection or carelessness.

RCDs are testable and resettable devices. They have a "test" button that when pressed it creates a small leakage condition and should activate a switch that disconnects the conductors and cut the power to the faulty device in that circuit.

Our tests force the RCD to trip and we measure the operating residual current and the trip time. If the RCD fails to trip or trip current is above 30mA or trip time is above 300ms then the RCD has failed and must be replaced.

Australian Standards

• Requirements are for RCDs to have a maximum sensitivity of 30mA.
• RCDs with a sensitivity of 30mA are designed to operate before fibrillation of the heart occurs.
• RCDs with a sensitivity of 10mA are designed to operate before muscular contraction, or inability to let go occurs. The use of a 10mA RCD may be considered in areas of increased risk, such as circuits within a doctors and dental surgery (body protected areas), supplying outdoor equipment, bathrooms and areas such as kindergartens.

STS test portable and fixed, single and 3 phase RCDs for visible damage, manual functionality, trip time, trip current at both phase 0° and 180°. Depending on the RCD type the test results must be within an acceptable parameter (as above). The test data is then recorded to give you an overview and condition of the RCDs tested.

Note: RCDs do not provide protection in all circumstances. For example, an RCD will not disconnect the electricity supply if a person contacts both active and neutral conductors while handling faulty plugs or electrical equipment and electricity flows through the person’s body, unless there is also a current flow to earth.