Which two common types of smoke detectors exist?

Battery-operated and 120-volt smoke detectors are indeed two of the most common types of smoke detectors. Battery-operated smoke detectors are popular due to their ease of installation and portability; they can be placed almost anywhere without the need for wiring. These detectors rely on batteries to operate, making them a great option for homes that do not have wired systems.

120-volt smoke detectors, on the other hand, are typically hardwired into a home's electrical system and usually come with a battery backup to ensure they function even during a power outage. The hardwired models are often interconnected, meaning when one detector senses smoke, all connected units will sound the alarm, providing an added safety feature.

Understanding these types helps in choosing the right smoke detection system for different environments, as both options cater to various needs and preferences.