Safety Switches
What is a safety switch?
Safety switches are designed to save lives. They detect the loss of current fro a circuit that indicates a person is receiving an electric shock, and they cut the power in as little as 30 milliseconds
Safety switches have been mandatory on the power outlet circuits of new homes since the early 1990s, and on the light and power circuits of new homes in most states since 2000. But many older homes do not have safety switches, and circuits such as air-conditioning, pool filters, hot water and stoves are not protected in most homes.
Types of home safety switches
Switchboard-mounted safety switches
This type of safety switch is the device required by law to be fitted to the power and lighting circuits of new homes. They are located alongside circuit-breakers in the home’s switchboard, and can be distinguished from circuit breakers by the presence of a button marked “test”, which is located on the front face of the device.
Combination safety switch and circuit breakers in switchboards
Some homes have a combined circuit breaker and safety switch installed on their power and lighting circuits. These devices protect the electrical circuits and appliances attached to them, but also offer the safeguards against electrical injury and death that can only be achieved with a safety switch. These devices cost around $100 more than a standard circuit breaker, and if installed at the time of construction do not require any additional labour than a standard circuit breaker.
Other types of safety switches
In older homes or in specific environments such as workshops or bathrooms, safety switches may be fitted to a power point. Again, this type of switch can be distinguished by the test button on its front face. In order to protect a circuit, the safety switch must be fitted to the first power point on a circuit.
Portable safety switches, attached to a power board or extension lead, are also available. These devices are designed specifically for people working with electrical tools, and only protect the circuits of appliances connected to them. They are often required under Workplace Health and Safety laws, in addition to or instead of testing and tagging of electrical equipment on workplaces. However, they are not adequate protection for the home environment.
How do Safety Switches work?
On a normal power circuit, the current flowing to an appliance returns through the neutral wire. If the circuit is compromised, the electricity can leak to earth through a person in contact with the appliance, causing death or serious injury.
A safety switch detects the loss of power from the circuit, and cuts the supply of electricity in as little as 30 milliseconds – 0.003 seconds. Importantly, this response time is faster than the critical section of a heartbeat, and therefore significantly reduces the risk of death or serious injury.
I have circuit breakers. Is that the same?
Circuit breakers and fuses are designed to protect the appliances and electrical fittings in your home. They do not protect human life, and will rarely shut off the power in the event of electric shock. Only safety switches will cut the power to a circuit in the event of earth leakage. Only safety switches can save lives and prevent injuries.
How do I know if I have a safety switch?
Safety switches have a “test” button on the front face. If the devices in your switch board do not have a test function, they are probably circuit breakers rather than safety switches. You should use the test button several times each year to test that the safety switch is working properly to cut the power. To minimise inconvenience, this can be done at the time clocks are adjusted at the start and finish of daylight savings time. Home owners can also take advantage of any power outage to test their safety switches – after the power is reconnected but before resetting their appliances.
I have a safety switch. Am I protected?
Many Australian homes have safety switches on the power outlet circuits, and some have safety switches on the lighting circuits. But in most homes, other circuits such as pools, air-conditioners, hot water systems and stoves are not protected. For the highest possible level of protection, you need a safety switch on every circuit.
A safety switch should always be considered a secondary safety response; it is not a substitute for old-fashioned common sense around electricity. A person who receives an electric shock from a circuit protected by a safety switch may still feel the current for an instant, and experience pain and shock. However, they are much more likely to survive than they would if the circuit was unprotected.