What is insulation resistance testing primarily used for?

Insulation resistance testing is primarily used to assess the effectiveness of insulation within electrical systems. The testing helps determine whether the insulation is intact and can adequately prevent electrical current from leaking out of conductors, which is crucial for safety and reliability. By measuring the resistance of insulation, technicians can identify any potential deterioration or faults that could lead to short circuits, equipment damage, or even electrical shocks.

While it is important for breakers to perform correctly, checking their performance is typically done through functional testing rather than insulation resistance testing. Similarly, circuit load balance involves ensuring that loads are evenly distributed across phases but is not directly related to insulation effectiveness. Measuring voltage levels is essential for system operation and troubleshooting but does not provide information regarding the condition of the insulation. Therefore, the focus on insulation effectiveness makes this option the correct choice.