What is a common use for mega ohm meters?

A mega ohm meter is primarily used for insulation testing. This instrument measures the resistance of insulation materials, which is crucial in determining whether electrical insulation is intact and functioning correctly. By applying a high voltage, typically in the range of 1,000 volts or more, a mega ohm meter can assess the quality of insulation surrounding conductors. If the insulation has degraded or there are faults present, the resistance reading will be low, indicating potential safety hazards or failures in the electrical system.

In contrast, other types of testing mentioned in the options involve different measurements and equipment. Voltage testing typically uses voltmeters to measure potential difference, while current testing uses ammeters to assess the flow of electric current through a conductor. Frequency testing relates to measuring the frequency of alternating current (AC) signals, which is not the primary function of a mega ohm meter. Understanding the specific uses of different testing equipment is crucial for ensuring safe and reliable electrical installations.