Equipment intended to interrupt current at fault levels shall have a current rating not less than the nominal circuit voltage and the available fault current at the line terminals.

• A. True
• B. False
• C. Not applicable
• D. Unknown

Answer: (B)

The main idea is that protective equipment designed to interrupt fault current must be rated for the actual electrical conditions it could encounter. A device like a circuit breaker or fuse has several ratings: a current rating (in amperes), a voltage rating (in volts), and an interrupting or fault-current rating (often in kiloamps). The current rating tells you the maximum continuous current it can carry, while the voltage rating tells you the maximum voltage it can safely operate at. The interrupting capacity tells you the maximum fault current it can safely interrupt without failing.

The statement mixes these concepts by saying the current rating should be not less than the nominal circuit voltage. That doesn’t make sense because current and voltage are different quantities with different units. The correct requirement is that the device’s voltage rating should be at least the nominal circuit voltage, and its current rating should be at least the nominal circuit current. In addition, the device’s interrupting capacity must be at least the available fault current at the line terminals.

So the claim is false because it mismatches what the ratings represent.