Insulation Resistance of Medium and Low Voltage Installations

Insulation resistance is an important parameter of electrical installations, especially for medium and low voltage systems. At a pressure of 500 volts applied between each live conductor and Earth for a period of 1 minute, the insulation resistance of medium and low voltage installations shall be at least 1 mega-ohm. Let's understand this in detail.

What is Insulation Resistance?

Insulation resistance is the resistance offered by the insulation material between the conductive parts and the earth or any other conductive material. It is measured in ohms and is an important parameter to ensure the safety and reliability of electrical installations.

Why is Insulation Resistance Important for Medium and Low Voltage Systems?

In medium and low voltage systems, insulation resistance is critical as it determines the safety of the system. If the insulation fails, it can result in electric shock, short circuits, or even fire hazards.

What is the Required Insulation Resistance for Medium and Low Voltage Systems?

As per the Indian Electricity Rules, at a pressure of 500 volts applied between each live conductor and Earth for a period of 1 minute, the insulation resistance of medium and low voltage installations shall be at least 1 mega-ohm. This means that the insulation resistance between each live conductor and earth should not be less than 1 mega-ohm.

How is Insulation Resistance Measured?

Insulation resistance is measured using an insulation resistance tester or a megger. The tester applies a high voltage between the conductive parts and the earth and measures the current flowing through the insulation. Based on the measured current, the tester calculates the insulation resistance.

Conclusion

Insulation resistance is an important parameter for medium and low voltage systems. As per the Indian Electricity Rules, the insulation resistance of medium and low voltage installations should be at least 1 mega-ohm at a pressure of 500 volts applied between each live conductor and earth for a period of 1 minute. Insulation resistance is measured using an insulation resistance tester or a megger.