Megohm meter test or insulation resistance test is a method of testing with the resistance meter of an insulation tester, which will help verify electrical insulation. Megameter meter tester has been in use since 1889 and became popular in the 1920s. Since the long-term design and testing purposes are the same, there has been little real improvement in the design and quality of the tester in recent years. High quality options are now available that are easy to use and reasonably safe.

Megger test is a kind of insulation test, it USES the applied dc voltage 250 Vdc, 500 Vdc 1000 Vdc (low voltage equipment) or < 600 v, 2500 Vdc and 5000 Vdc (high voltage equipment) to measure k Ω, M Ω or G Ω insulation resistance. The resistance measured is intended to indicate the condition of the insulation or dielectric between two conducting parts, where the higher the resistance, the better the insulation. Ideally, the insulation resistance should be infinite, but since there is no perfect insulator, the leakage current through the dielectric will ensure that the measured resistance is limited (albeit high).

Why megohm meter testing?

The insulation resistance quality of electrical systems decreases with time and environmental conditions (such as temperature, humidity, moisture, and dust particles). It is also negatively affected by the presence of electrical and mechanical stresses, so it is essential to regularly check the IR (insulation resistance) of the equipment to avoid the risk of death or shock.

On the other hand, if your home has just caught fire, you need to start the rebuilding process. Your insurance company tells you that your local jurisdiction or the insurance company itself requires a megogram test to verify the integrity of the wiring system in your home.

Megohm meter testing doesn't cause any damage, so it's a good option when someone doesn't want to drill holes in a wall to see if there are any problems with electrical insulation. The test equipment only works between 500 and 1,000 volts, which is relatively low. Due to low voltage, some breakdown in the insulation went undetected. It usually provides information about leakage currents and whether there is too much dirt or moisture in the insulation area and the amount of moisture, deterioration, and winding faults.