What type of current do circuit breakers and OCPDs generally interrupt?

Circuit breakers and overcurrent protective devices (OCPDs) are typically designed to interrupt alternating current (AC) circuits. This is primarily because the majority of electrical power systems, especially in residential and commercial applications, operate using AC power.

When an overcurrent event occurs, such as a short circuit or an overload, the circuit breaker is activated. In the case of AC circuits, the breaker interrupts the flow of electricity at the zero-crossing point of the current waveform, making it easier to extinguish the arc created during the interruption. This ability is due to the characteristics of AC, where the current reverses direction, allowing the electrical arc to extinguish more readily compared to direct current (DC).

While there are specialized circuit breakers for DC applications, standard household and most commercial circuit breakers are not primarily focused on DC interruption. They can face challenges when interrupting DC since the current does not naturally return to zero, making it more difficult to interrupt without arc quenching techniques.

This context clarifies why the correct identification of the type of current that common circuit breakers and OCPDs interrupt is primarily alternating current.