Engineering & Technology
WWW.CLARVIS.CO.UK
WWW.CLARVIS.CO.UK
Safe isolation is about ensuring that the circuit you are working on is not live and cannot be made live by anyone but yourself.
A whole installation can be isolated via the main switch or an individual circuit can be isolated via the MCB of the circuit required.
The outline of the procedure is described below:
1. Obtain permission to start working.
2. Lock off the isolator or MCB using a lock-off device and safety padlock. Keep the key in your possession.
3. Prove that the voltage indicator is functioning correctly using the proving unit.
4. Prove the circuit is not live using the voltage indicator following the sdequence shown below.
5 .Prove that the voltage indicator is still functioning correctly using the proving unit.
6. Postition signs to tell other people that the installation has been isolated.
7. Work can begin.
When testing the voltage of three-phase circuits, stage 4 should be carried out by testing the voltage between:
1. L1 and L2
2. L1 and L3
3. L1 and Neutral
4. L1 and Earth
5. L2 and L3
6. L2 and Neutral
7. L2 and Earth
8. L3 and Neutral
When testing the voltage of single-phase circuits, stage 4 should be carried out by testing the voltage between:
1. Line and Neutral
2. Line and Earth
3. Neutral and Earth