Electrical Exam Term

Interrupting Rating

The maximum fault current that an overcurrent device (breaker or fuse) can safely interrupt without being damaged or causing a hazard.

Detailed Explanation

NEC 110.9 requires all overcurrent devices to have an interrupting rating sufficient for the available fault current at their line terminals. Standard residential breakers are typically rated 10,000 amps. Commercial and industrial breakers may be rated 14,000 to 200,000 amps or more. If a fault exceeds the device's interrupting rating, the device may rupture, arc, or explode, creating a serious fire and safety hazard.

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