Which situation allows for the installation of smoke detectors in elevator hoistways?

The installation of smoke detectors in elevator hoistways is permitted when the elevator system is equipped with smoke relief equipment. This requirement exists because smoke relief systems provide a mechanism to mitigate smoke buildup in the hoistway during a fire, enhancing the safety of the elevator's operation. When equipped with this kind of system, smoke detectors can effectively serve their purpose by detecting smoke and alerting relevant parties, while the smoke relief equipment actively works to clear smoke from the hoistway, allowing for safe egress and preventing smoke from entering the elevator car.

Other options may not meet the specific safety requirements set forth by building codes and standards for elevator systems. For instance, the mere presence of operational elevators or the installation of detectors on each floor does not guarantee a safe condition for the hoistway. Wireless models might be convenient, but without proper smoke relief measures in place, they would not fulfill the requisite safety protocols for installation in that context.