How often should a safety switch be tested?

A residual current device is a mechanical device with moving parts that sits untouched for years in a hot, dusty box. It can seize. The test button exists because the only way to know it still works is to make it work, and a quarterly rhythm is the interval most Australian electrical safety regulators publish.

How to test one

1. 1Warn anyone in the house, and shut down computers first, because power will drop.
2. 2Press the button marked T or TEST on each safety switch in turn.
3. 3The switch should trip to the off position immediately.
4. 4Switch it back on. If anything did not come back, that circuit needs looking at.
5. 5If a device does not trip, stop using it as protection and have it replaced.

One thing worth knowing: a safety switch that trips repeatedly, on its own, without you touching it, is usually not faulty. It is doing its job and finding real leakage somewhere, often in an appliance or in wiring that has taken water. Repeatedly resetting it and hoping is the wrong response.