Residual current devices (RCDs)

Electric shock often results from people making contact with energised parts of damaged or faulty electrical equipment.

RCDs cut the electricity supply instantly if a person touches a live part and receives a shock.  Serious injuries and fatalities may be prevented by the use of properly installed and maintained RCDs, sometimes called ‘safety switches’.

While RCDs significantly reduce the risk of electric shock they do not provide protection in all circumstances. It is important to regularly check electrical equipment, cords and lights for damage, and use electrical equipment safely.

An appropriate RCD must be used, so far as is practicable, if electrical equipment is used in an environment that is likely to result in damage to the equipment or a reduction in its expected life span. This includes equipment that:

• is exposed to moisture, heat, vibration, mechanical damage, corrosive chemicals or dust
• is moved between different locations where damage to the equipment or its cord could occur
• is frequently moved during its normal use
• forms part of, or is used in connection with, an amusement device.

The exceptions to this requirement are if the supply of electricity to the electrical equipment:

• does not exceed 50 volts alternating current
• is direct current
• is provided through an isolating transformer that provides at least an equivalent level of protection, or
• is provided from a non-earthed socket outlet supplied by an isolated winding portable generator that provides at least an equivalent level of protection.

Where an RCD is required, it must have a tripping current that does not exceed 30 milliamps if electricity is supplied to the equipment through a socket outlet not exceeding 20 amps.

RCDs can be non-portable or portable. The most ‘appropriate’ RCD will depend on the workplace environment.

You may need to seek technical advice from a licensed electrical worker, or other competent person, about the kinds of RCDs that are appropriate for your workplace.

Common examples of electrical equipment requiring an RCD include:

• hand-held electrical equipment, for example drills, saws, hair dryers, curling wands and electric knives
• electrical equipment that is moved while in operation, including jackhammers, electric lawn mowers, floor polishers and extension cords
• electrical equipment that is moved between jobs in ways that could result in damage to the equipment, for example electric welders, electric cement mixers, portable bench saws and extension cords.

Non-portable (‘fixed’) RCDs are RCDs that are installed at either the switchboard or a fixed socket outlet and protect the wiring connected to the RCD and electrical equipment plugged into the protected circuit.

Portable RCDs are generally plugged into a socket outlet and, depending on design, may protect one or more items of electrical equipment.

RCDs used at the workplace must be tested regularly by a competent person to ensure the devices are working effectively. This requirement covers RCDs used in all operating environments including non-portable (‘fixed’) RCDs.

The PCBU should determine how often an RCD should be tested, by either conducting a risk assessment that considers the type of RCD and operating environment or consulting a competent person, such as a licensed electrical worker.

A record of testing (other than daily testing) must be kept until the device is next tested or disposed of.

If an RCD is tested and found to be faulty it must be taken out of service and replaced as soon as possible.

A new portable RCD unit should be tested by pressing the ‘trip test’ button to ensure the RCD is effective.

Construction and demolition sites have additional electrical safety requirements, and must comply with AS/NZS 3012:2010/Amdt 1:2015: Electrical installations – Construction and demolition sites.

There are additional requirements for RCDs in residential properties. If your workplace is also a residential property, such as an apartment, house or unit, or if your business or undertaking is involved in property sale, leasing or management, please refer to Building and Energy’s Residual current devices webpage.