What is the typical insulation resistance of equipment rated at 480V?

The correct answer, 100 megohms, aligns with industry standards for insulation resistance testing in electrical equipment rated at 480V. Insulation resistance is critical for ensuring the safety and reliability of electrical installations. Typically, a minimum insulation resistance of 100 megohms is accepted for 480V equipment to ensure that the insulation is sufficient to prevent leakage currents that could lead to equipment malfunction or electrical hazards.

This standard reflects the need for high insulation quality at such voltage levels, given the potential risks associated with electrical faults. An insulation resistance of 100 megohms indicates good insulation integrity, reducing the likelihood of electrical shock or fire caused by current leakage through insulation failure.

While other options suggest higher values, such as 250 megohms, those are typically reserved for applications with higher safety margins or more sensitive equipment, not generally typical for standard 480V installations. Thus, 100 megohms is the established industry benchmark for effective insulation resistance at this voltage level, ensuring safe and reliable operation of electrical equipment.