What is a common testing device used to check insulation resistance?

An insulation resistance tester, commonly referred to as a megohmmeter, is specifically designed to measure the insulation resistance of electrical wiring and components. This device applies a high voltage, usually between 250V to 1000V, to the insulation, allowing it to quantify the resistance offered by the insulation material. High resistance values indicate good insulation, while low values can suggest deterioration or faults within the insulation.

Using a megohmmeter is crucial in ensuring that electrical systems are safe and operating efficiently. It helps prevent electrical failures and hazards that may arise from poor insulation, such as shorts or electrical fires.

While a multimeter can measure various electrical parameters, it doesn't provide the high voltage necessary to accurately test insulation resistance. Similarly, a continuity tester is designed for checking the continuity of circuits rather than measuring insulation resistance, and a frequency counter is used for measuring the frequency of electrical signals, not insulation integrity. Thus, the insulation resistance tester stands out as the appropriate choice for this application.