Chapter 1: Photoelectric Smoke Detector — Light-Scatter Principle

Cutaway diagram of a photoelectric smoke detector optical chamber showing the LED emitter, angled photodiode receiver, light-scatter path when smoke particles are present, and labyrinth baffle housing

Comparison diagram of ultraviolet, infrared, and multi-spectrum infrared flame detector technologies showing detection principle, response speed, and common false-alarm sources for each

Installation diagram of linear heat detection cable mounted with standoff clips along a cable tray and ceiling run, terminating at an end-of-line device wired back to the fire alarm control panel

Reference table and diagram of NFPA 72 minimum candela requirements for visible notification appliances by room size, corridor width, and ceiling height, including synchronization requirements

Waveform diagram of the standardized Temporal-3 (T3) fire alarm audible notification pattern showing three half-second tone pulses, half-second silences, and a 1.5 second pause repeating continuously

Cross-section of a large open volume space showing a projected beam smoke detector transmitter and receiver mounted on opposite walls with the infrared beam path and maximum spacing dimensions

Healthcare facility floor plan diagram showing smoke compartments separated by smoke barrier doors, corridor smoke detectors, and the defend-in-place horizontal relocation strategy

Side-by-side wiring diagram comparing a Class B one-way circuit terminated with an end-of-line resistor against a Class A two-way redundant loop circuit returning to the fire alarm control panel

Building wiring topology diagram showing the initiating device detection bus and the separate notification appliance bus branching from the fire alarm control panel through risers and floor runs

Addressable signaling line circuit field wiring diagram showing a T-tapped Class A loop with short-circuit isolator modules branching to individually addressed smoke detectors and modules

Block diagram of signal flow through an initiating device circuit, from field device activation through wiring supervision to the fire alarm control panel

Fire alarm control panel front face diagram with labeled LED indicators for alarm, supervisory, trouble, AC power, and system normal conditions using standard red, yellow, and green color convention

Fire alarm control panel elevation drawing showing the cabinet dimensions, lockable door, LCD display, and keypad layout with silence, acknowledge, and reset buttons

Network transmission diagram showing a fire alarm control panel connected through a dual-path IP and cellular communicator to an off-site central monitoring station and the local fire department

Power supply configuration diagram showing primary AC power feeding the fire alarm control panel and battery charger, with secondary battery backup power sized for 24 hour standby plus alarm duration

Worked battery capacity calculation table listing standby and alarm current draw per device, total standby and alarm ampere-hours, safety factor applied, and selected standard battery size

Battery load test setup diagram and voltage discharge plot over time showing a healthy battery holding voltage above the minimum acceptance threshold through the full standby and alarm test duration

Fire alarm control panel display in walk test mode showing test status indicator, running count of devices tested, and address-by-address confirmation list

System diagram connecting a wet-pipe sprinkler system

Reference sheet summarizing NFPA 72 National Fire Alarm and Signaling Code, NFPA 101 Life Safety Code, NFPA 70 National Electrical Code, and additional applicable codes including IBC, IFC, and NFPA 1