Equipment intended to interrupt current at fault levels must have an interrupting rating at nominal circuit voltage that is at least what?

For equipment designed to interrupt current at fault levels, it is essential that the interrupting rating matches or exceeds the maximum fault current that can flow under nominal circuit voltage conditions. The interrupting rating indicates the maximum amount of current that the protective device, such as a circuit breaker or fuse, can interrupt safely without causing failure or danger.

When considering the correct option, it is important to recognize that the fault current can be significantly higher than the normal operating load current. Therefore, having an interrupting rating equal to the current available at the line terminals of the equipment ensures that the device can handle potential fault conditions without risking failure. This level of protection is critical to maintaining system safety and operational reliability.

In summary, an interrupting rating that is equal to the current available at the line terminals provides the necessary assurance that the equipment can effectively manage fault conditions.