A brief discussion over the phone gives us relevant information on what kind of fault we might be dealing with. This information will be useful and will give us a head start on locating the problem before we arrive on site.
Once we arrive on site our first protocol will be to gather as much information as possible and some brief checks on the switchboard to see if the safety switch resets. If the safety switch fails to reset we will visually investigate lighting and power equipment and if nothing cant be found with the naked eye the test equipment will need to be brought into action.
The insulation resistance test is one of the first tests we do, this test will determine if the insulation on the cable has deteriorated and if the current is leaking were it shouldn’t be. A good insulation test will have high resistance but never perfect as all known insulation will have a small amount of leakage currents, small enough so that it doesn’t cause trouble with the safety switches. This test is undertaken by using an IR tester and can cause current to flow around the insulation of the cable and can measure up-to to a 1000 volts.
The half test method is another well known test we like to carry out by using the IR tester, splitting a circuit in half will show which side has the low resistance reading and which side has the high resistance reading. Having a low resistance reading will show the circuit is in contact and working correctly and high resistance meaning the circuit is faulty and further investigation is needed to find the leaking currents. The side with the low resistance reading will also need to be split in half until the location of the fault is found.