An insulation fault is indicated by which insulation resistance reading?

An insulation fault is indicated by which insulation resistance reading?

• A. Very high insulation resistance
• B. Abnormally low insulation resistance
• C. Insulation resistance is constant
• D. No insulation resistance measurement

Answer: (B)

Insulation resistance measures how well insulation blocks current flow. When insulation is healthy, it resists leakage and the reading is very high. If there’s an insulation fault, leakage paths form—due to moisture, contamination, or damaged insulation—allowing current to leak more easily. That shows up as an abnormally low insulation resistance reading during the test. So a low reading indicates the insulation isn’t performing properly and a fault is present. Seeing a very high insulation resistance would mean the insulation is in good condition, not a fault. A constant reading isn’t diagnostic by itself, and no measurement simply means you can’t assess the condition without testing.

Insulation resistance measures how well insulation blocks current flow. When insulation is healthy, it resists leakage and the reading is very high. If there’s an insulation fault, leakage paths form—due to moisture, contamination, or damaged insulation—allowing current to leak more easily. That shows up as an abnormally low insulation resistance reading during the test. So a low reading indicates the insulation isn’t performing properly and a fault is present.

Seeing a very high insulation resistance would mean the insulation is in good condition, not a fault. A constant reading isn’t diagnostic by itself, and no measurement simply means you can’t assess the condition without testing.