What Are the Basics of Fire Alarm Wiring?

Knowing the proper method of fire alarm wiring is an important factor in fire safety and the protecting life and property from fire. Unlike the complex fiber-optic and coaxial cables and wires used to connect computer networks, most of the basic fire alarm wiring technology used today has remained relatively unchanged through the years. The exception is the newer addressable fire alarm systems which utilize better designed sensing equipment and more reliable fire detection devices.

The environment into which fire alarm wiring is installed determines the specific type and rating of the cable or wiring to be used. For example, fire alarm wiring installed in a consistently wet environment necessitates the use of a different wiring standard than wiring installed in a dry environment. All fire alarm wiring systems are required to comply with the requirements of Underwriters Laboratories in the US or with other electrical wiring standards established by local building code authorities.

There are two basic types of fire alarm systems and each is wired differently. The first, conventional fire alarm systems, have enjoyed a long track record of reliability and provide most of the commercial and industrial fire alarm protection in buildings around the world today. Conventional detectors or sensors are composed of wired circuits that cover a certain area or zone of a building. The various circuits are directly wired to the fire control panel.

This type of fire alarm system is typically less expensive than addressable fire alarm systems and provides detection for the zone where the fire alarm is sounding. Conventional systems use more standard wiring and do not provide the specific location of a fire. Neither do they identify a specific alarm or input sensing device.

Addressable fire alarm systems, also known as intelligent systems, function by assigning a unique address to every input sensor or device such as heat detectors, smoke alarms, and pull switches. Addressable fire alarm systems can precisely pinpoint the exact location of a fire because each individual sensing device is connected directly to an annunciator panel. A single pair of wires can connect up to 200 individual devices to the main fire alarm system. This type of system uses less wiring than conventional fire alarm systems and makes troubleshooting easier since technicians can isolate faulty devices quickly.

The National Electric Code provides a guidelines for fire alarm system installation and fire alarm wiring. The electrical and fire alarm wiring codes established by current local state, county, parish, province, and other governing authority must be carefully followed. The best practice for anyone handling or installing fire alarm wiring is to check with the local authorities and determine the specific requirements established in local electrical and construction codes. Working within established codes and with local construction authorities is a basic requirement for fire alarm installation. The local authority or fire marshal will have final authority to approve or deny the installation of any and all fire alarm wiring.