IL Fire Alarm key terms

The wiring path connecting automatic or manual initiating devices to the fire alarm control unit, monitored so opens, shorts, or grounds are annunciated as trouble conditions rather than silently disabling detection.

The output circuit that powers and controls audible and visible signaling appliances such as horns, strobes, and speakers, sized so voltage at the end of the line stays within appliance listing limits.

A system in which each initiating or signaling device has a unique address, letting the control unit report the specific device in alarm or trouble instead of only the circuit it sits on.

A system organized by circuits or zones rather than individual device addresses, so an alarm identifies the zone of origin while individual device identity is not reported.

A signaling circuit whose wiring leaves the control unit and returns on a separate path, so a single open or ground fault does not prevent operation of devices on the circuit.

A circuit wired out from the control unit and ending at the last device, where a single open fault disables all devices beyond the break and is annunciated as a trouble condition.

A resistor installed at the far end of a supervised Class B circuit that allows the control unit to monitor wiring integrity and detect opens or shorts in the loop.

Continuous electronic monitoring of circuit integrity, power sources, and system components so that failures are annunciated at the control unit as trouble signals before a fire occurs.

A distinct audible and visible indication at the control unit that a fault exists in the system, such as a wiring break, power loss, or device failure requiring attention.

The signal produced by the system when an initiating device operates, causing notification appliances to sound and the control unit to display the alarm condition.

A detector that samples air at a single location to sense smoke, commonly using photoelectric light-scattering or ionization technology, and is listed for specific spacing and mounting conditions.

A smoke detector that responds when smoke particles scatter light inside a sensing chamber, generally more responsive to visible smoke from smoldering fires.

A smoke detector that senses changes in an electric current flowing through ionized air when combustion particles enter the chamber, typically responding faster to flaming fires with small particles.

The maximum listed distance between smoke detectors and from detectors to walls, used with the coverage-area rules to lay out detection so smoke reaches a detector in the required time.

A detector that projects a light beam across a protected space and senses smoke obscuration along the path, used for large open areas such as atriums and warehouses.

A detector installed in an air-handling duct to sense smoke moving through the HVAC system, typically used to initiate fan shutdown or smoke control functions.

A detection system that draws air from a protected area through a network of pipes to a central sensing unit, allowing very early warning in spaces where point detectors are impractical.

A device that responds to fixed temperature, rate of temperature rise, or both, used where smoke detection is unsuitable or where ambient conditions would cause smoke detectors to nuisance alarm.

A manually operated initiating device, mounted at accessible heights along exit paths, that lets a person activate the fire alarm system when fire or smoke is observed.

An audible, visible, or voice device such as a horn, strobe, or speaker that alerts occupants, with visible appliances rated in candela and audible appliances rated in decibels.

A flashing light signal, rated in candela, intended to warn occupants including those with hearing loss, with intensity and flash rate governed by accessibility standards.

A sound signal produced by horns or speakers, measured in decibels and required to exceed ambient noise by a specified margin so occupants throughout the protected area can hear it.

Coordination of flash timing and sound patterns among notification appliances in the same area so that visible signals flash together and do not create an increased seizure risk.

A notification system that delivers prerecorded or live voice messages over speakers, allowing staged evacuation instructions and often required in high-occupancy or high-rise buildings.

The method of computing conductor voltage loss on notification circuits using current, conductor resistance, and length to confirm appliances receive their listed operating voltage.

The main commercial or utility power source serving the fire alarm control unit, which must be dedicated and provide the capacity needed to operate the system under normal conditions.

The backup source, typically rechargeable batteries or an engine-driven generator, that sustains the fire alarm system for a specified duration when primary power fails.

The documented computation of standby and alarm current demands multiplied by required time durations, used to select battery capacity and verify charger sizing.

A defined area or circuit grouping of initiating devices reported together by the control unit, used in conventional systems to identify the general location of an alarm.

The central panel that receives signals from initiating devices, processes them, activates notification appliances, and annunciates alarm, supervisory, and trouble conditions.

A signal indicating a change in the condition of a system component, such as a closed valve or a switch in an off-normal position, that could impair fire protection if uncorrected.

The documented functional test performed after installation to verify that the system and its components operate as designed before the authority having jurisdiction approves the installation.

The recurring program of visual inspection, functional testing, and servicing of fire alarm components at frequencies set by code to keep the system reliable over its service life.

A document prepared at installation that records system features, device counts, and as-built details, used as the baseline for later inspection and testing.

The organization or official responsible for approving equipment, installations, and procedures, and for enforcing the adopted fire code in the local jurisdiction.

The National Fire Alarm and Signaling Code, which sets requirements for the design, installation, testing, and maintenance of fire detection and notification systems.

The National Electrical Code, which governs electrical installation requirements including wiring methods, overcurrent protection, and grounding that apply to fire alarm circuits.

The Life Safety Code, which addresses means of egress, occupancy requirements, and where fire detection and alarm systems must be provided in buildings.

The Fire Code, which consolidates fire prevention and protection requirements, including maintenance of fire alarm systems and references to other codes.

The formal authorization issued by the local authority to perform fire alarm installation or alteration work, typically required before work begins and closed out after inspection.

The credential issued by the state or local authority that authorizes a person or business to engage in fire alarm contracting, installation, or maintenance work within its scope.

The business entity responsible for contracting fire alarm work, holding required state or local credentials and carrying insurance and bonding as required by law.