A smoke detector must not be installed in elevator hoistways except if which condition is met?

A smoke detector is generally not permitted in elevator hoistways due to concerns about false alarms and the potential for smoke to be removed from a hoistway before it can be detected. However, if sprinkler coverage is provided in the hoistway, this condition allows for the installation of smoke detectors.

When sprinklers are installed, they can help to control or suppress a fire situation, effectively lowering the risk of smoke accumulation that could lead to false alarms. The presence of sprinklers means that if a fire were to occur in the hoistway, the system is designed to mitigate smoke spread, allowing a smoke detector to function without the same level of false alarm risk that exists in hoistways without such protection.

This balance of safety measures allows for the use of smoke detectors while maintaining the integrity of fire safety standards and reducing the potential hazards associated with false positives.