What type of tester measures insulation integrity by assessing very high resistances?

A megohmmeter is specifically designed to measure high resistance values, which is crucial for assessing the integrity of insulation in electrical systems. This tool applies a high voltage to the insulation and measures the resistance, allowing technicians to determine if the insulation is effective in preventing current leakage. This is particularly important in ensuring safety and functionality within electrical installations, as deteriorated insulation can lead to short circuits or electrical shocks.

A multimeter can measure resistance, but it is generally limited to lower ranges and is not suitable for evaluating the high resistances found in insulation materials. A clamp meter is primarily used for measuring current and does not assess resistance directly. A continuity tester checks for continuity in circuits, which involves lower resistance values, and does not provide information on high resistance as a megohmmeter does. Therefore, for testing insulation integrity, a megohmmeter is the most appropriate tool.