MT Fire Alarm key terms
MT Fire Alarm · Get comfortable with the vocabulary.
- Initiation Device
- Related: Notification Appliance, Initiating Device Circuit, Alarm Signal
A component such as a smoke detector, heat detector, manual pull station, or waterflow switch that starts a signal in the fire alarm system when it senses fire, smoke, or human action.
- Notification Appliance
- Related: Notification Appliance Circuit, Alarm Signal, Audible/Visible Appliance
An audible or visible device such as a horn, speaker, or strobe that alerts occupants when the system is in alarm. These devices are wired on notification appliance circuits and must meet audibility and visibility requirements.
- Initiating Device Circuit (IDC)
- Related: Initiation Device, Class A Circuit, Class B Circuit
The wiring path connecting initiation devices to the control panel. It carries the signal that tells the panel a device has operated, and its style determines how it responds to a single fault such as an open or short.
- Notification Appliance Circuit (NAC)
- Related: Notification Appliance, Supervision, Voltage Drop
The circuit supplying power to horns, strobes, and speakers. It is designed to deliver the current the appliances need and may be supervised so that a break or short is annunciated at the panel.
- Addressable System
- Related: Conventional System, Address, Zone
A fire alarm arrangement in which each device has a unique address so the panel can identify the exact device that operated. This speeds troubleshooting and lets the panel report a precise location to responders.
- Conventional System
- Related: Addressable System, Zone, Initiating Device Circuit (IDC)
A fire alarm arrangement where devices are grouped on circuits by zone rather than individually identified. The panel reports the zone, not the specific device, so field personnel must search the zone to find the activated unit.
- Zone
- Related: Conventional System, Annunciator, Addressable System
A defined area or group of devices reported together by the fire alarm panel. Zones are used for annunciation, and their size and boundaries affect how quickly responders can locate the source of an alarm.
- Annunciator
- Related: Zone, Control Panel, Trouble Signal
A remote display panel that shows zone or device status, such as alarm, trouble, or supervisory conditions. It is typically placed where staff or responders can see system information away from the main control panel.
- Control Panel
- Related: Annunciator, Trouble Signal, Supervision
The central unit that receives signals from initiation devices, processes them, and operates notification appliances. It also monitors circuit integrity and displays alarm, trouble, and supervisory conditions for the building.
- Supervision
- Related: Trouble Signal, Class B Circuit, Notification Appliance Circuit (NAC)
The continuous monitoring of circuit wiring and system components so that a break, short, or power loss is detected and reported. Supervised circuits help ensure the system will still function when a fire occurs.
- Trouble Signal
- Related: Supervision, Control Panel, Ground Fault
An indication at the control panel that a fault exists, such as an open circuit, ground fault, or loss of primary power. Troubles must be investigated and corrected because the system may not operate properly until resolved.
- Alarm Signal
- Related: Notification Appliance, Initiation Device, Supervisory Signal
The signal produced when a system detects fire or smoke and enters the alarm state. It typically activates notification appliances and is distinguished from trouble and supervisory signals on the panel.
- Supervisory Signal
- Related: Alarm Signal, Trouble Signal, Waterflow Switch
A signal indicating that a system component or condition needs attention, such as a closed valve on a sprinkler system or a low air pressure condition. It is distinct from an alarm or a trouble signal.
- Waterflow Switch
- Related: Supervisory Signal, Initiation Device, Alarm Signal
A device that senses water movement in a sprinkler pipe and sends an alarm signal to the fire alarm panel. It is typically set with a delay so that minor pressure fluctuations do not cause false alarms.
- Smoke Detector
- Related: Initiation Device, Heat Detector, Detector Spacing
A device that senses smoke and initiates an alarm. Common types include ionization and photoelectric, and placement must follow code and manufacturer instructions to avoid nuisance alarms and ensure timely response.
- Heat Detector
- Related: Smoke Detector, Initiation Device, Detector Spacing
A device that responds to a rise in temperature or to a fixed high temperature and then initiates an alarm. It is used where smoke detection is unsuitable, such as kitchens or dusty areas.
- Detector Spacing
- Related: Smoke Detector, Heat Detector, Coverage Area
The maximum distance allowed between detectors and from walls, based on the detector listing and code requirements. Correct spacing ensures that a fire is detected before it grows too large.
- Class A Circuit
- Related: Class B Circuit, Initiating Device Circuit (IDC), Supervision
A circuit whose wiring is arranged so that a single open fault does not prevent operation of devices beyond the fault. It provides a redundant path and is often used for critical signaling circuits.
- Class B Circuit
- Related: Class A Circuit, Supervision, Trouble Signal
A circuit that does not continue to operate all devices after a single open fault. A break disables devices beyond the break, and the fault is reported as a trouble condition at the panel.
- Audible/Visible Appliance
- Related: Notification Appliance, Notification Appliance Circuit (NAC), Audibility
A notification device combining a sounder and a strobe in one unit. It must meet code requirements for sound level and flash rate so occupants with hearing or vision limitations can be alerted.
- Audibility
- Related: Audible/Visible Appliance, Notification Appliance, Alarm Signal
The required loudness of alarm signals at various locations in a building, measured in decibels above ambient sound. Codes set minimum levels so alarms can be heard over background noise in occupied spaces.
- Voltage Drop
- Related: Notification Appliance Circuit (NAC), Ohm's Law, Conductor Resistance
The loss of voltage along a circuit caused by resistance in the conductors. On notification circuits, excessive drop can prevent appliances from operating properly, so wire size and load must be calculated.
- Ohm's Law
- Related: Voltage Drop, Power Formula, Conductor Resistance
The relationship stating that voltage equals current multiplied by resistance. Technicians use it to calculate loads, expected current, and voltage drop when designing and troubleshooting fire alarm circuits.
- Power Formula
- Related: Ohm's Law, Battery Calculation, Voltage Drop
The relationship stating that power in watts equals voltage multiplied by current. It is used to determine whether a circuit or battery can supply the energy needed by connected devices.
- Battery Calculation
- Related: Power Formula, Secondary Power Supply, Supervision
The process of sizing standby batteries to supply the system during a power outage for a required time, plus alarm load. It considers current draw, required standby hours, and a safety margin.
- Secondary Power Supply
- Related: Battery Calculation, Trouble Signal, Supervision
The backup source, usually rechargeable batteries, that keeps the fire alarm system operating when normal building power fails. Codes require it to support the system for a specified duration.
- Ground Fault
- Related: Trouble Signal, Supervision, Conductor Resistance
An unintended connection between a conductor and ground that can disrupt circuit operation or create a shock hazard. Fire alarm panels typically supervise for ground faults and report them as a trouble condition.
- Conductor Resistance
- Related: Voltage Drop, Ohm's Law, Ground Fault
The opposition to current flow within a wire, which increases with length and decreases with larger wire size. It causes voltage drop and must be considered when selecting conductors for alarm circuits.
- Overcurrent Protection
- Related: Ground Fault, Conductor Resistance, Power Formula
A device such as a fuse or circuit breaker that interrupts current when it exceeds a safe level. It protects conductors and equipment from damage caused by short circuits or overloads.
- Raceway
- Related: Conductor Resistance, Supervision, Ground Fault
An enclosed channel such as conduit or tubing that holds and protects wiring. Proper raceway selection and installation help prevent physical damage to fire alarm cables and support reliable system operation.
- Fire Alarm Contractor License
- Related: Individual Certification, Scope of Work, AHJ
A Montana credential authorizing a business to install, maintain, or service fire alarm systems. The license is issued under state law and is separate from the individual installer's certification or registration.
- Individual Certification
- Related: Fire Alarm Contractor License, Scope of Work, Continuing Education
A personal credential held by a technician who performs fire alarm work. It demonstrates that the individual has met the training or examination requirements set by the state for that type of work.
- AHJ
- Related: Permit, Plan Review, Inspection
The authority having jurisdiction, meaning the organization or official responsible for approving installations and enforcing the applicable fire and building codes in a given area, such as a local fire marshal or building department.
- Scope of Work
- Related: Fire Alarm Contractor License, Individual Certification, Permit
The specific tasks and system components a licensed contractor is authorized to perform under its license classification. Working outside that scope can violate state licensing law and may void insurance coverage.
- Permit
- Related: AHJ, Plan Review, Inspection
Official approval required before certain fire alarm work begins. It confirms that plans have been reviewed and allows inspections to be scheduled as the installation progresses.
- Plan Review
- Related: Permit, AHJ, Inspection
The process in which an authority examines submitted fire alarm drawings and specifications for code compliance before construction. Approval is typically needed before installation or permit issuance.
- Inspection
- Related: Permit, Plan Review, AHJ
An official examination of installed fire alarm work to verify it matches approved plans and meets code. Passing inspection is usually required before a system is placed into service.
- Continuing Education
- Related: Individual Certification, Fire Alarm Contractor License, Scope of Work
Required ongoing training that licensees complete to renew their credential. It keeps technicians current on code changes, technology, and safety practices throughout their careers.
- Lockout/Tagout
- Related: Personal Protective Equipment, Hazard Assessment, Arc Flash
A safety procedure that isolates energy sources and applies locks and tags before work begins. It prevents accidental energizing or release of stored energy that could injure workers servicing equipment.
- Personal Protective Equipment (PPE)
- Related: Lockout/Tagout, Hazard Assessment, Fall Protection
Safety gear such as gloves, eye protection, hard hats, and hearing protection worn to reduce injury risk. Employers must provide suitable PPE and train workers on its proper use and limitations.
- Hazard Assessment
- Related: Personal Protective Equipment (PPE), Lockout/Tagout, Fall Protection
The process of identifying workplace dangers and deciding how to control them before work starts. It considers tasks, equipment, environment, and worker experience to select appropriate safeguards.
- Fall Protection
- Related: Personal Protective Equipment (PPE), Hazard Assessment, Ladder Safety
Systems and practices that prevent or arrest falls when working at height, such as guardrails, harnesses, and lanyards. Proper training and equipment inspection are required before use.
- Ladder Safety
- Related: Fall Protection, Hazard Assessment, Personal Protective Equipment (PPE)
Practices for setting up, climbing, and working from ladders, including maintaining three points of contact and correct angle. Selecting the right ladder and inspecting it reduce fall and electrical hazards.
- Arc Flash
- Related: Lockout/Tagout, Personal Protective Equipment (PPE), Hazard Assessment
A sudden release of energy caused by an electrical fault that produces intense heat, light, and pressure. Workers should de-energize equipment and use appropriate protective equipment to avoid serious injury.