What is the minimum wire size for Class 3 single-conductors?

For Class 3 circuits, the National Electrical Code (NEC) specifies that the minimum wire size for single-conductor installations is 18 AWG (American Wire Gauge). This size is suitable for the lower voltage levels typically utilized in Class 3 circuits, which are designed to carry signals and provide power without exceeding 100 volts.

Using 18 AWG wire ensures that the conductors can handle the necessary current without significant voltage drop or overheating, which is crucial for maintaining the integrity and performance of fire alarm systems. The choice of this specific gauge reflects industry standards and safety practices, ensuring that the wiring is both reliable and compliant with relevant codes and regulations.

In fire alarm systems, proper wiring is essential for the functionality and safety of the system, particularly considering the importance of maintaining signal integrity and minimizing interference. As such, adhering to the minimum wire size requirements is fundamental to ensuring effective system operation.