Which of the following is NOT classified as an underground test device?

The correct answer is D, as a power meter is not classified as an underground test device.

Underground test devices are specifically designed to measure electrical properties in scenarios where equipment or wiring is located underground, such as in the case of transmission lines, grounded circuits, or other underground installations.

An ohmmeter is used to measure resistance, which is crucial when assessing the integrity of underground conductors and connections. A voltmeter helps in measuring voltage, which is essential to ensure proper operation and safety of underground systems. A megohmeter, also known as an insulation resistance tester, is used to measure high resistance values, typically used to test the insulation of cables in underground settings.

In contrast, a power meter is generally used to measure the real power flowing in a circuit and is more suited for above-ground applications, particularly in residential, commercial, and industrial settings where the overall electrical performance needs to be monitored rather than the specific conditions present within an underground installation. Thus, a power meter does not fit the classification of underground test devices.