What device is specifically used to measure insulation resistance?

The most appropriate device for measuring insulation resistance is the insulation resistance tester. This specialized instrument is designed to apply a high voltage to the insulation of electrical systems, which allows for an accurate assessment of the insulation's integrity. By measuring the resistance in ohms, the tester can determine whether the insulation is effective in preventing leakage currents that could lead to equipment failure or safety hazards.

While other devices such as multimeters can measure resistance, they do so at low voltages that may not adequately stress the insulation to reveal potential problems. Similarly, clamp meters are primarily used for measuring current in conductors without having to disconnect them, and circuit testers are generally meant for verifying the functionality of circuits and ensuring proper connections rather than measuring insulation specifically. The nature of the insulation resistance tester makes it the most reliable and suitable choice for this task.