If you’re carrying out electrical work on an existing installation it’s important to ensure you follow the correct sequence of testing. Failure to do so can put you and the people who use the installation at risk.

Sequence of electrical testing can also cause damage to the equipment being tested and may invalidate the results of the tests you are performing – so it’s worth understanding the correct order.

When working on an existing installation the first step is to carry out a visual inspection, this allows the electrician to confirm that permanently wired equipment is in good condition and that all fire barriers, protective-, monitoring-, isolating- and switching devices are present and functioning. This is then followed by a more thorough inspection & test procedure to determine the safety of the installation.

The six mandatory tests required by law include:

Polarity test:

This test ensures that no parts of the circuit are connected to a live phase conductor. It can be carried out by using a multimeter with a continuity setting. Touch the probes to two points on the circuit and note the reading. If the meter indicates that the voltage is flowing in the correct direction, the reading will be positive. If not, the meter will indicate that the voltage is flowing in the wrong direction and can be potentially fatal.