What is an approved disconnecting means for ungrounded conductors that pass through buildings?

The correct choice indicates that both a circuit breaker and a molded case switch can serve as approved disconnecting means for ungrounded conductors that pass through buildings. This aligns with the National Electrical Code (NEC) requirements, which specify that all ungrounded conductors must have a means of disconnection to ensure safety and facilitate maintenance.

A circuit breaker is designed to automatically interrupt the flow of electrical current in case of overloads or short circuits, making it a reliable option for quickly disconnecting power. It is widely used due to its ability to provide overcurrent protection while also serving as a means to disconnect power.

A molded case switch, on the other hand, is a manually operated switch that can handle larger loads and is also intended for use as a disconnecting device. It offers a robust and durable solution suitable for industrial applications, where larger conductors are common.

Both devices ensure that maintenance personnel can safely isolate power to the conductors, thereby preventing the risks associated with electrical shock when performing service or maintenance work.