Electrical Module 26405-23: Fire Alarm Systems

Objectives and Introduction to Fire Alarm Notification

  • Module Theme: This module focuses on Section 4.0.0 of Electrical Module 26405-23, covering Fire Alarm Systems, specifically notification, communication, and monitoring aspects.
  • Primary Objectives for Section 4:
    • Identify and describe various approaches used for fire alarm notification, communication, and monitoring.
    • Describe specific visual and audible notification devices and the systems they comprise.
    • Explain the critical considerations required when using fire alarm notification signals.
    • Detail the various options available for the communication and monitoring of fire alarm systems.

Notification Appliances and Devices

  • General Notification Types: There are two primary categories used to alert occupants, alongside secondary methods for specific needs:

    • Audible Notification: Sound-based alerts.
    • Visible Notification: Sight-based alerts.
    • Olfactory Notification: Smelled-based alerts (less common).
    • Tactile Notification: Touch-based or vibration alerts (less common).

  • Visual Notification Devices (4.1.1):

    • Strobes: These are high-intensity flashing lights utilized for visual notification.
    • Placement: Strobes are typically wall-mounted or ceiling-mounted, often located near audible devices.
    • Synchronization Requirements: If two or more strobes are visible from a single location, they must be synchronized to flash at the same time to prevent triggering seizures or disorientation in sensitive individuals.
    • Color Specifications: Per the Americans with Disabilities Act (A D A), fire alarm strobe lights are required to be either clear or white.

  • Audible Notification Devices (4.1.2):

    • Device Types: Common devices include sirens, bells, and horns.
    • Signal Synchronization: If a building contains other sounds or signals, the fire alarm must be synchronized to produce a unique, recognizable sound pattern.
    • Temporal-Three Pattern: Most fire alarm systems are required to utilize a standardized signal pattern known as Temporal-Three.
    • Decibel Limits: In public areas, at the minimum hearing distance, an audible alarm should not exceed a maximum loudness of 110 dBA110\,\text{dBA}.

  • Voice Evacuation Systems (4.1.3):

    • Function: These systems provide specific verbal instructions to occupants during an emergency rather than just a tone.
    • Note on Signaling: The Temporal-Three signaling pattern is NOT utilized with zoned voice evacuation systems.

Signal Considerations and Communication

  • Authorized Signals (4.2.0): Codes authorize specific signal types depending on the application:

    • General signal
    • Attendant signal
    • Pre-signal
    • Positive alarm sequence
    • Voice evacuation

  • Character of Signals:

    • Decibel (dB\text{dB}) Levels: A critical consideration for the effectiveness and safety of audible signals.
    • Coded vs. Non-coded: Signals may be pulsed in a specific code or be continuously energized.

  • Monitoring Options (4.3.0–4.3.1): Systems are monitored by external or internal stations to ensure emergency response:

    • Supervising station
    • Proprietary station
    • Certified supervising station

Communication and Signal Transmission Technology

  • Digital Alarm Communicator Transmitters (D A C T) (4.3.2):

    • Mechanism: A D A C T uses standard public switched telephone network (P S T N) lines to transmit and receive data.
    • Legacy Status: While found in many existing legacy installations, this method is rarely used in new installations today.
    • RJ-31X Device: This specific device is used to connect a D A C T to a standard voice-grade telephone line, ensuring the alarm system can seize the line even if a telephone is in use.

  • Modern Transmission Methods (4.3.3–4.3.4):

    • Primary Technologies: Modern systems primary utilize Cellular technology, Internet Protocol (I P), or Radio for signal transmission.
    • Backup Requirements: Any system that utilizes P O T S (Plain Old Telephone Service) or P S T N (Public Switched Telephone Network) is required to have one of the modern methods (Cellular, I P, or Radio) as a backup.

Trade Terms

  • Americans with Disabilities Act (A D A): An act of Congress intended to ensure civil rights for physically challenged people.
  • Audible Signal: The sound made by one or more audible indicating appliances, such as bells, chimes, horns, or speakers, in response to the operation of an initiating device.
  • Chime: A single-stroke or vibrating audible signal appliance that has a xylophone-type striking bar.
  • Coded Signal: A signal pulsed in a prescribed code for each round of transmission.
  • Digital Alarm Communicator Transmitter (D A C T): A system component at a protected premises to which initiating devices or groups of devices are connected. The D A C T will seize the connected telephone line, dial a preselected number to connect to a digital alarm communicator receiver (D A C R), and transmit signals indicating a status change of the initiating devices.
  • General Alarm: A term usually applied to the simultaneous operation of all audible alarm signals on a system to indicate the need for evacuation of a building.
  • Indicating Device: Also known as a notification appliance or device.
  • Noise: A term used in electronics to cover all types of unwanted electrical signals. Noise originates from sources such as fluorescent lamps, walkie-talkies, amateur and C B radios, machines being switched on and off, and power surges. Equipment quality is often measured by how much noise it can withstand or ignore.
  • Non-coded Signal: A signal from any indicating appliance that is continuously energized.
  • Public Switched Telephone Network (P S T N): An assembly of communications facilities and central office equipment, operated jointly by authorized common carriers, providing the public with communication channels via discrete dialing codes.
  • Remote Supervising Station Fire Alarm System: A system installed in accordance with the applicable code to transmit alarm, supervisory, and trouble signals from one or more protected premises to a remote location where appropriate action is taken.
  • Wide Area Telephone Service (W A T S): Telephone company service providing reduced costs for certain call arrangements.
    • In-W A T S (800-number): Calls can be placed to the called party at no cost to the caller.
    • Out-W A T S: A flat-rate service allowing a subscriber to make unlimited calls within a prescribed area for a flat-rate charge based on duration.

Questions & Discussion

  • Question 1: The A D A specifies that fire alarm strobe lights must be clear or what other color?
    • Answer: b. white
  • Question 2: At minimum hearing distance, a public area audible alarm should be no louder than what level?
    • Answer: c. 110 dBA110\,\text{dBA}
  • Question 3: Digital communicators connect to telephone lines with which specific device?
    • Answer: a. R J-31X