When is a smoke detector allowed to be installed in an unsprinklered elevator hoistway?

A smoke detector can be installed in an unsprinklered elevator hoistway only if it’s needed for elevator operation. This is generally because smoke detectors play a crucial role in ensuring the safety of elevator systems and their occupants. In the context of an unsprinklered area, the detector would serve to enhance safety protocols, especially in case of a fire, which could compromise the elevator’s use and the safety of individuals who might be using it during an emergency.

In situations where fire alarm systems are required, having a smoke detector in the hoistway could be essential to ensure that any smoke or heat detection triggers appropriate safety measures, facilitating both safety and better functionality for the elevator.

The other options do not accurately reflect the requirements or limitations of smoke detector installation in elevator hoistways, as they either suggest a wider allowance than is appropriate, such as being allowed all the time without conditions, or prohibit installation entirely, which does not meet safety standards or operational requirements given specific scenarios.