Back to Basics: Fire Alarm Systems

Fire alarm systems are a great tool for notifying fire department resources about a fire, system activation, or alarm condition. Unfortunately, too many false alarms have allowed fire department staff to lower their guard.

For many fire departments false fire alarms have become a nuisance and have lead to changes in response policies due to the number of alarms. The response may limit the number of units on the initial alarm, only the first due engine responds with lights and sirens, or none of the units respond with lights and sirens. Once the crews arrive on the scene of the alarm, there is typically an investigation on the cause of the alarm and if necessary the fire is extinguished. Many times, the cause is undetermined or unfounded and the system is reset and the companies return back to quarters. With false alarms, many communities begin to penalize building owners when the department has responded to a predetermined amount of false alarms. Many times the owner will have the alarm system serviced or may elect to change the procedures for the alarm company in a non approved fashion.

A fire alarm system that has been designed, installed, and maintained will provide a system that is not prone to false alarms. Properly designed fire alarm systems begin with the building owner or architect soliciting for an alarm company to design and install a fire alarm system. The designer should be show competencies in design of fire alarm systems and have credentials for the design. Credentials may come in the form of National Institute for Certification in Engineering Technologies (NICET), Professional Engineer, local or state certification as an alarm company. Proper credentials ensure that the designer has a background in commercial fire alarm applications. The fire prevention bureau has more control of fire alarms that are installed in the commercial setting over residential systems. The influence on fire alarms in the residential setting are typically through education of home owners as compared to enforcement powers in commercial buildings.

Because there are differences in the requirements found in model building and life safety codes, the designer must be capable in understanding code requirements and equipment specifications. The first exposure a municipality has to a fire alarm system is the plan review process. A complete plan review is the foundation for the overall performance in the system. The fire prevention bureau should be trained in fire alarm plan review and the requirements of the system. Basic fire alarm submittals should include:

  • Scope of work including construction type and use group classification
  • Construction drawings commonly referred to as shop drawings which include the use of the room, and location of all alarm devices with wiring locations.
  • Fire alarm control equipment including manufacture information
  • Line or riser diagram which indicates all of the devices on a single sheet of paper
  • Power connections including secondary power
  • Voltage drop calculations including cable (wiring) size based on the shop drawings or riser diagram
  • Battery calculations
  • Annunciation of the alarm system or zone nomenclature
  • Details on the ceiling height and construction
  • Any interface to other fire safety functions
  • Copy of the preliminary record of completion

These items are the foundation for a basic alarm system design. Contractors who struggle to provide this documentation at plan review may provide an inferior system or lack the skills necessary in proper system design. The plan reviewer will look for code compliance on the documents utilizing the adopted fire code which typically references National Fire Protection Association (NFPA) 72, National Fire Alarm Code. This standard is the basis for "application, installation, location, performance, inspection, testing, and maintenance of fire alarm systems, fire warning equipment and emergency warning equipment, and their components" (Scope of NFPA 72). The plan reviewer shall ensure code compliance and if the documents do not meet the requirements of the jurisdiction the plans should be returned to the contractor for corrections.

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