Which statement about Megger testing is true?

• A. It measures insulation resistance by applying high DC voltage.
• B. It uses alternating current only.
• C. It does not pose any hazard.
• D. It requires no PPE.

Answer: (A)

Megger testing focuses on evaluating insulation by applying a high direct current voltage across it and measuring the leakage current to determine insulation resistance. When the instrument applies a known DC voltage, the resulting current through the insulation is used to calculate resistance (R = V/I). The higher the insulation resistance, the better the insulation condition. This DC approach helps avoid capacitive effects that can distort readings seen with AC. The idea that it uses alternating current only is incorrect, because a Megger delivers DC voltage. It does pose hazards due to high voltage, so PPE and proper safety procedures are essential. It also does not imply that no PPE is needed or that there are no risks.