The Correct Sequence of Electrical Testing

Whether you’re working on a new electrical installation, or carrying out an initial verification inspection or periodic test on an existing one, it’s vital that the tests are carried out in the correct sequence. Not only can doing so minimise the risk of electric shock for yourself and others, it’s also necessary to ensure that your electrical system is compliant with BS7671 and satisfies statutory regulations such as the Electricity at Work Regulations.Source :

Here’s how to do it:

1. Visually inspect the installation.
This includes checking that all protective conductors are intact and properly connected. It also means making sure that all switchboards are correctly labelled, and that RCDs and fuses have the appropriate ratings for the circuit they’re on.

2. Check the continuity of the ring final circuit.

In order to check the continuity of a ring’s final circuit, you’ll need to connect your multimeter to each socket in turn. Then, by switching the meter to the resistance setting, you’ll be able to see which of the three wires are connected in series. The meter should show infinity if there’s an open circuit, or zero if it’s closed.

3. Verify the polarity of the phase conductors.

This is important because if there’s incorrect polarity, parts of the installation may still be connected to the live phase conductor when a single-pole switch is off, or an over-current protection device has tripped. This can be done by connecting the tester to a piece of cable with known resistance, and then to the live of the furthest socket in the circuit to be tested. The reading you achieve will need to be deducted from the total insulation resistance result for that circuit.