OSHA 30 Hour Construction Program Practice Test

Which smoke alarm is quicker to respond in slower, smokey fires?

1. Ionization smoke alarms

2. Photoelectric smoke alarms

3. Thermal alarms

4. Alarm systems with integrated sensors

The correct answer is: Photoelectric smoke alarms

Photoelectric smoke alarms are designed to be particularly effective at detecting smoldering fires, which typically produce a large amount of smoke but not much heat initially. These types of alarms use a light source and a sensor; when smoke enters the sensing chamber, it scatters the light, triggering the alarm. This mechanism allows them to respond more quickly to fires that produce visible smoke from smoldering materials, such as upholstery or electrical wiring. In contrast, ionization smoke alarms are generally more responsive to fast-flaming fires with less smoke, while thermal alarms depend on heat detection and may not activate until the temperature increases significantly. Alarm systems with integrated sensors might provide a broader range of detection capabilities, but the specific attribute of detecting slow, smoky fires is particularly characteristic of photoelectric alarms. Hence, for fires characterized by a slower burn and increased smoke production, photoelectric smoke alarms are the most effective choice.