What does a megger primarily test?

• A. Insulation capabilities by applying a high voltage and measuring leakage.
• B. Voltage regulation under load.
• C. Phase balance in a three-phase system.
• D. Ground fault current path.

Answer: (A)

Megger testing focuses on insulation resistance. It applies a high DC voltage across insulation and measures how much current leaks through. The result, expressed in megaohms, shows how well the insulation can resist leakage—higher resistance means better insulation and lower risk of failure. This direct measurement of leakage current under high voltage is exactly what a megger is designed to assess.

That’s why this option is the best fit: it describes checking insulation capabilities by applying a high voltage and measuring leakage. The other options describe different kinds of tests—voltage regulation under load, phase balance, or ground fault current paths—which are not what a megger measures.