It is important for professional electricians to know the proper procedure in using electrical test instruments. These includes the proper selection of test probes, voltage indicating devices and the actual measuring device. This is because it has been proven from the past that there are several instances where the electrical accidents involves misuse of electrical test instruments. For this reason, many manufacturers enhanced the safety features of the test instruments sold in the market.
The test probes
- The probes must have finger barriers or be shaped so that the hand or fingers cannot make contact with the live conductors under test.
- The probe tip must not protrude more than 2 mm, and preferably only 1 mm, be spring-loaded and screened.
- The lead must be adequately insulated and colored so that one lead is readily distinguished from the other.
- The lead must be flexible and sufficiently robust.
- The lead must be long enough to serve its purpose but not too long.
- The lead must not have accessible exposed conductors even if it becomes detached from the probe or from the instrument.
- Where the leads are to be used in conjunction with a voltage detector they must be protected by a fuse.
Doing Live Testing
- Be trained so that he understands the equipment and the potential hazards of working live and can, therefore, be deemed to be ‘competent’ to carry out the activity;
- only use approved test equipment;
- set up barriers and warning notices so that the work activity does not create a situation dangerous to others.
Electrical Supply Isolation
Actual Test Procedure
- The circuits must be isolated using a ‘safe isolation procedure’, such as that described below, before beginning to test.
- All test equipment must be ‘approved’ and connected to the test circuits by recommended test probes mentioned above. The test equipment used must also be ‘proved’ on a known supply or by means of a proving unit.
- Isolation devices must be ‘secured’ in the ‘off’ position.
- Warning notices must be posted.
- All relevant safety and functional tests must be completed before restoring the supply.