Interrupting rating refers to which of the following?

• A. The rating required for interrupting equipment to handle fault levels.
• B. The efficiency rating of transformers under load
• C. The thermal capacity of cables
• D. The frequency range of signals in a control circuit

Answer: (A)

Interrupting rating is the maximum fault current a protective device can interrupt safely. It tells you the level of short-circuit current the device is designed to break without failing, which is essential for preventing damage, arcing hazards, and unsafe conditions during a fault. This rating must be at least as high as the worst-case prospective fault current at the device’s location in the system, ensuring reliable clearing of faults.

The other ideas don’t fit because they describe different concepts: efficiency under load, the thermal capacity of cables, or the frequency range of signals—none of which specify the device’s ability to interrupt a fault current.