🔍 Key Concepts

• Insulation resistance testing and what a megger measures • Difference between condition-based criteria and time-based or purely visual maintenance • What indicates deterioration of insulation in electrical equipment

💭 Think About

• Which option directly reflects the electrical condition of the insulation rather than appearance or elapsed time? • Does a high or a low measurement of insulation resistance suggest contamination, moisture, or breakdown of insulation? • Among the choices, which criterion would most reliably show that insulation is no longer providing adequate resistance to leakage current?

✅ Before You Answer

• Verify what a megger reading represents: high vs low values in terms of insulation health • Consider whether dirt or moisture on insulation tends to increase or decrease insulation resistance • Check which answer choice is a quantitative indicator of insulation condition, not just a schedule or simple visual cue