Safety Switches And Electrical Testing

A safety switch is designed to cut power in a fraction of a second when current leaks to earth, which is what happens when a person becomes part of the circuit.

It is a mechanical device. It can fail, and when it fails it usually fails without any indication at all.

Safety switch or circuit breaker

These get confused constantly and they do different jobs.

A circuit breaker protects the wiring from overload and short circuit. It stops the cable overheating. It does not protect a person.

A safety switch, an RCD, monitors the difference between the active and neutral current and trips when it detects leakage to earth. It protects people.

An RCBO does both in one device, which is what most modern switchboards use.

A switchboard full of circuit breakers and no RCD is common in older buildings and it means nobody in the building has that protection, whatever the board looks like.

What coverage should look like

Modern requirements have moved steadily toward RCD protection on all final subcircuits, and a board upgraded years ago frequently has protection on power points only, with lighting, the oven, the air conditioner and the hot water left unprotected.

Lighting circuits are the one people find surprising. Changing a light fitting is exactly the situation where an RCD matters.

Where a board is being touched for any reason, extending the protection to the remaining circuits is a small incremental cost at that moment and a separate job later, which is the argument in [switchboard upgrades in older buildings](/blog/switchboard-upgrades-in-older-buildings).

Testing

The test button confirms the mechanism operates. Press it, the switch trips, reset it. That is a monthly job for an owner or occupier and it takes ten seconds.

Pressing it is worth doing for one reason: a switch that does not trip on the button is definitely faulty.

Instrument testing measures the actual trip time and trip current against the required limits. This is what confirms the device works at the speed a person depends on, and the test button cannot tell you that.

A switch can pass the button test and fail an instrument test, which is why the button is a check rather than a certification.

For rented properties

Electrical safety obligations for rental properties are specific and they carry consequences.

Safety switch testing and record keeping sit alongside [smoke alarm compliance](/blog/smoke-alarm-compliance-in-a-rented-property) as the items an agent has to be able to evidence, and the record matters as much as the test. A test with no documentation is an unprovable test.

Batching this across a portfolio at the same visit as the smoke alarms is the practical way to keep it current, rather than chasing each property separately.

The faults we find

No RCD protection at all on lighting or on fixed appliances.

A switch that will not reset, which is usually a genuine fault on a circuit rather than a faulty switch. Repeatedly resetting it is a bad idea.

Nuisance tripping, frequently a failing appliance, a water affected outlet, or moisture in an outdoor circuit. It is a real fault and worth tracing rather than bypassing.

A switch bypassed by an earlier installer to stop it tripping. Rare and serious.

An RCD past its life, and they do have one. Trip times lengthen with age, and an instrument test is the only way to see it.

The short version

Press the test button monthly. Get an instrument test at the intervals that apply to the property, and keep the record.

Ample does safety switch and smoke alarm testing across managed portfolios in the eastern suburbs and inner city, with the certificates issued in a form an agent can file.