A fire alarm system includes a control panel, initiating devices (like smoke and heat detectors), notification devices (such as alarms and strobes), a power supply (main and backup), and wiring.

The control panel receives signals from initiating devices. It processes these signals and decides the response, such as sounding alarms or alerting authorities.

Smoke detectors sense smoke and signal the control panel. The fire alarm system then alerts occupants and may trigger other safety measures.

There are two main types: conventional (zone-based) and addressable (device-specific with location tracking).

Common initiating devices include smoke detectors, heat detectors, manual pull stations, and sometimes gas detectors.

Notification appliances include horns, strobes, speakers, bells, and text displays that provide audible and/or visible alerts.

NFPA 72 is the main standard for fire alarm system design, installation, and maintenance.

Fire alarm systems should be tested at least once a year for code compliance. Regular visual inspections are also recommended.

A fire alarm system test includes checking devices for damage, activating initiating devices, verifying control panel response, confirming notification device function, recording results, and ensuring code compliance.

Backup power keeps systems running during outages, usually from batteries or generators.

Ionization detectors work best for fast-flaming fires, while photoelectric detectors are better for smoldering fires.

Wet pipe systems have water and activate immediately. Dry pipe systems use pressurized air; water flows in when activated, often in freezing areas.

Maintenance tasks include visual inspection, testing for sound and visibility, checking strobe synchronization, and documenting any issues.

When working on fire alarm systems, disable the system, confirm power is off, wear PPE, follow lockout/tagout procedures, and comply with OSHA/NFPA rules.

Fire alarms in hazardous locations need explosion-proof enclosures, intrinsically safe wiring barriers, and regular inspections.

To calculate battery capacity, add the standby current for 24 hours and the alarm current for 5 minutes. Then increase by 20–25% for safety.

Addressability means each device has a unique address, allowing the panel to identify the exact source of activation or trouble.

NFPA 72 compliance ensures the system meets standards, helps with insurance, and supports best safety practices.

Consider building size, layout, fire risk, and legal requirements when choosing a fire alarm.

The minimum sound level for residential fire alarms is usually rated at 85 dBA at a specified distance for code compliance.

The most common causes include faulty wiring, loose connections, power supply interruptions, dead backup batteries, environmental factors (such as dust or steam triggering detectors), malfunctioning smoke or heat detectors, and issues with the control panel. Regular inspection and timely maintenance can help resolve these problems and ensure reliable system operation.