Importance of IR
Insolation Resistance (IR) is the test to confirm if an appliance is tripping the RCD (Residual Current Device) in the property. Whether there is a live/neutral path tracking to earth. This is an important test to carry out at both the start of the job and at the end once the job has been completed and is tested along side the Earth Continunity test. The purpose of a trip is to prevent you or the customer from getting an electric shock. If a live wire was to touch the bare casing of the appliance and the customers house electrics or more importantly the earth circuit was faulty, by doing this test you would avoid an electric shock or worse death!
1
Switch On The Meggar
Firstly, the meggar should be set on the lowest volts setting either 240v or 500v.
2
Connecting The Leads/Testing
One of the meter leads should be connected to the earth pin on the plug, and the other connected on to the live pin on the plug. The test should be repeated on the earth pin and neutral pin. The appliance needs to be in the ON position to test with the door closed.
When testing an appliance that is hard wired in to a spur, it is important to disconnect the cable from the spur before testing to prevent false readings.
3
Readings
The British standard pass for and IR test is anything above 2.00 Mohms. Anything between 2.00 and 0.00 Mohms is a fail and investigation needs to be carried out. At One Stop we are not happy with anything under a reading of 10.00 Mohms unless there is a valid reason.
Switch Meggar on to its lowest setting 240v or 500v
Connect leads to both the earth pin and live/neutral
Press the test button and take reading (> 2Mohms)