What is the minimum size for single conductors in fire alarm systems?

The minimum size for single conductors in fire alarm systems is 18 AWG. This size is specified due to the requirements set by the National Fire Protection Association (NFPA) and the National Electrical Code (NEC) for fire alarm applications. The 18 AWG conductor is adequate to support the electrical and signaling health of the system while maintaining the necessary resistance for effective communication in the event of a fire.

Using a conductor that is 18 AWG ensures that the wire has sufficient strength and current-carrying capacity to handle the demands of a fire alarm system, which may be operating in conditions where reliability is critical. Additionally, this size helps maintain the integrity of the electrical signals, reducing the risk of false alarms or system failures due to insufficient conductor capacity.