CSLB Class B General Contractor's License Practice Exam

Which type of wire is used to connect one smoke detector to another?

1. 10/2

2. 12/2

3. 12/3

4. 14/3

The correct answer is: 14/3

The correct type of wire used to connect one smoke detector to another is the 14/3 wire. This wire consists of three conductors plus a ground wire, making it ideal for interconnecting multiple smoke detectors while ensuring that they can function as a single system. The three conductors allow for the connection of detectors in a series and facilitate the connection of power, as well as allow for a secondary signal wire which can be used to interconnect alarms. This configuration is important for safety, as it enables a chain reaction where if one smoke detector senses smoke, it can trigger the others to sound an alarm, providing greater safety throughout the area. The other options, such as 10/2, 12/2, and 12/3, do not offer the same combination of conductors necessary for linking smoke detectors. For instance, 10/2 and 12/2 have only two conductors, making them inadequate for interlinking multiple alarms. Similarly, while 12/3 has three conductors, it typically is not utilized for such applications due to being heavier gauge and less flexible than the 14 AWG wire, which is standard for low-voltage applications like smoke detectors.