DE Fire Alarm key terms

The wiring path connecting automatic detectors and manual pull stations to the fire alarm control unit so their alarm, trouble, and supervisory signals reach the panel. It may be conventional or addressable and is supervised against opens, shorts, and grounds.

The circuit supplying power and signals to horns, strobes, speakers, and other warning devices. It must be electrically supervised and designed so a single fault cannot silence all notification in the protected area.

A detector, module, or appliance with its own unique address that the control unit can identify individually, letting the panel report the exact device in alarm or trouble rather than only the circuit.

A fire alarm arrangement where devices connect to circuits grouped into zones, so the panel reports only which zone activated, not the specific device. Troubleshooting requires field-by-field investigation along the circuit.

A defined area of a protected premises, or a group of devices, identified on the control unit so responders can locate the origin of a signal. Zone size for conventional systems is limited by code based on floor area.

A remote display panel that repeats control unit status such as alarms, troubles, and zone or device identification at a location away from the main panel, often near a main entrance for arriving fire crews.

The central component that receives signals from initiating devices, processes them, activates notification appliances, and monitors system integrity. Also called the fire alarm control panel; it provides the interface for operator control and annunciation.

An addressable system where detectors report analog values, such as smoke obscuration levels, to the panel, which applies programmed thresholds or algorithms to decide when to signal an alarm, rather than relying on a detector's own fixed trip point.

A detector whose sensing element responds to conditions at a single location or small area, such as a ceiling-mounted smoke or heat detector, as distinguished from projected-beam or line-type devices covering long distances.

A device that senses products of combustion, such as visible smoke particles or obscuration, and initiates an alarm signal. Common types are ionization, photoelectric, and air-sampling; selection depends on expected fire characteristics.

A device that responds to thermal energy from a fire, typically by fixed temperature, rate-of-rise, or both. It is slower than smoke detection but more tolerant of dust, steam, and fumes that cause false smoke alarms.

A detector that projects a light beam across a protected space to a receiver and signals alarm when smoke obscures the beam. It suits large, high-ceilinged areas where spot detectors at the ceiling would be impractical.

The maximum distance between detectors, and between detectors and walls, permitted by code for a ceiling type and height. Spacing is based on listed coverage area and is reduced or adjusted for high ceilings, beams, and airflow.

A manually operated initiating device, typically at an exit or along a path of egress, that lets a person send an alarm signal by pulling a handle or lever. It must be accessible, unobstructed, and mounted at the required height.

A device on a sprinkler system that detects sustained water flow in a pipe and sends an alarm signal to the fire alarm control unit, distinguishing actual flow from pressure surges by a built-in time delay.

A device that monitors the position of a valve controlling water supply to a sprinkler system and sends a supervisory signal when the valve is moved from its normal open position, alerting staff to impaired protection.

A signal from the fire alarm system indicating a fire or other emergency condition requiring immediate response. It activates notification appliances and is distinct from trouble and supervisory signals.

A signal indicating a condition that could impair the system's ability to protect, such as a closed sprinkler control valve or low water level. Supervisory conditions require prompt attention but are not fire alarms.

A signal indicating a fault in the system itself, such as an open circuit, ground fault, loss of primary power, or battery failure, that could compromise performance. It sounds a distinctive audible and visual indication at the control unit.

The continuous electrical monitoring of circuits and components so that a fault, such as an open, short, or ground, produces a trouble signal rather than leaving the system silently inoperative. Supervision is required for initiating and notification circuits.

An unintentional connection between a circuit conductor and earth or the enclosure, which can prevent proper operation or cause false signals. The control unit must detect and annunciate ground faults as a trouble condition.

A supervised circuit that remains operational despite a single open or ground fault, because the wiring is arranged so the path continues to function. It provides a higher level of reliability than a Class B circuit.

A supervised circuit that will not function beyond a single open fault, since the fault interrupts the path to devices downstream. It signals the fault as a trouble but does not maintain full operation past the break.

The normal source of electrical energy for the fire alarm system, usually a dedicated commercial power branch circuit. It must be connected ahead of other loads and be protected against accidental disconnection.

The backup source, typically sealed lead-acid batteries or an engine-driven generator, that powers the system when primary power fails. It must be sized to carry the system load for a specified duration.

The process of determining required battery capacity by adding standby current over the required standby period to alarm current over the alarm period, then applying a derating factor for aging and temperature.

The period during which the secondary power supply must operate the system with no alarm present, commonly 24 hours, followed by a specified alarm duration such as 5 or 15 minutes depending on system type.

An audible or visible device, such as a horn, speaker, strobe, or chime, that warns occupants of an alarm condition. Appliances are selected and placed to meet required sound levels and visible signal coverage.

The signaling mode in which audible and visible appliances are intended to alert all occupants of a protected area, including those in sleeping areas, rather than only staff or designated responders.

The signaling mode in which notification appliances are intended to alert only those persons directly responsible for taking action, such as staff in an area not meant for general occupant notification.

The required sound pressure level of alarm notification, generally at least 15 dBA above ambient or 5 dBA above a maximum ambient of 105 dBA, measured at a specified distance from the appliance.

A visible notification appliance that emits high-intensity light flashes to alert hearing-impaired occupants and to supplement audible signaling. Flash rate, intensity, and synchronization are regulated by code and listing.

A continuous and unobstructed path of travel from any point in a building to a public way, including exits and exit access. Fire alarm devices and appliances are located with reference to this path.

A visual and physical examination of the fire alarm system to confirm it is installed as designed, undamaged, and unobstructed. Inspection is distinct from testing, which verifies actual function.

The operational check of fire alarm components and circuits, such as activating detectors and confirming signal transmission, to verify that the system performs as intended. Frequencies and methods are set by code.

The work of repairing, cleaning, recalibrating, or replacing fire alarm components so the system continues to function reliably between tests. Deficiencies found during inspection or testing drive maintenance actions.

A document, prepared at installation and updated over the life of the system, that records system design, device locations, and configuration details. It is required for proper inspection, testing, and maintenance.

Plans reflecting the fire alarm system as actually installed, including device locations, circuit routing, and panel configuration. They support future inspection, testing, maintenance, and modifications to the system.