Under what conditions should smoke detectors not be installed?

Smoke detectors are designed to operate within specific environmental conditions to ensure their reliability and effectiveness in detecting smoke. The correct response identifies that smoke detectors should not be installed in temperatures below 32 degrees Fahrenheit and above 100 degrees Fahrenheit.

When temperatures drop below 32 degrees, the components within the smoke detector can be affected. For instance, water vapor may freeze, which could compromise the detector's functionality. Similarly, extremely high temperatures (above 100 degrees) can lead to false alarms or may impair the detector’s ability to function properly due to the heat impacting its electronic components.

The other options do not adequately define conditions under which smoke detectors should not be installed. For example, while temperatures above 120 degrees are indeed unfavorable, the critical thresholds for installation, according to most standards, are within the ranges specified in the correct choice. Relative humidity below 50% usually does not impede the functioning of smoke detectors, as many detectors can handle a wide range of humidity. Likewise, air velocity less than 100 feet per minute is generally not problematic for smoke detector operation, as they are designed to respond to smoke particulates in static air conditions as well.