The correct answer isB. Theinterrupting ratingof electrical equipment is the maximumsymmetrical fault currentthat the device has been tested and certified tosafely interruptat its rated voltage and under specified conditions. In switchgear, circuit breakers, and related protective devices, this rating is critical because it confirms the equipment can open a faulted circuit without rupture, fire, excessive damage, or danger to personnel.
The term doesnotrefer to thepeakorcrestcurrent value. Peak or crest current is associated more closely withmomentary withstand,closing, orshort-circuit current peak effects, not the formal interrupting rating used for breaker application. It also does not mean ordinaryload current, because interrupting ratings are concerned with abnormal fault conditions rather than normal operating current.
From an API source inspection perspective, the inspector verifies that the nameplate data, test reports, and purchase specification all agree on the required interrupting capacity. If the interrupting rating is below the available fault current of the system, the equipment is unsuitable for safe service. Therefore, the correct definition is thesymmetrical current rating safely interruptible by the device.