Before megger testing, the circuit components should be _______ from the power supply.

Before megger testing, the circuit components should be _______ from the power supply.

• A. removed
• B. connected
• C. energized
• D. active

Answer: (A)

When using a megger to test insulation resistance, the circuit must be de-energized and isolated from the power source. The megohmmeter applies a high DC voltage to the insulation, and if the circuit is still connected to a live supply, that supply can backfeed into the test setup, damage equipment, or skew readings. Removing the components from the power source eliminates any live energy and stored energy in the circuit, such as capacitors, which could release during the test. Once isolated, you can safely apply the megger and obtain an accurate insulation-resistance measurement.

When using a megger to test insulation resistance, the circuit must be de-energized and isolated from the power source. The megohmmeter applies a high DC voltage to the insulation, and if the circuit is still connected to a live supply, that supply can backfeed into the test setup, damage equipment, or skew readings. Removing the components from the power source eliminates any live energy and stored energy in the circuit, such as capacitors, which could release during the test. Once isolated, you can safely apply the megger and obtain an accurate insulation-resistance measurement.