ME Fire Alarm cheat sheet

Article 725 covers remote-control, signaling, and power-limited circuits: Class 1 (power-limited within limits of 725.41, or non-power-limited), Class 2 (inherently limited or listed supply with low energy), and Class 3 (power-limited supply but higher voltage/energy than Class 2).

Class 2 and Class 3 circuit conductors must be separated from electric light, power, Class 1, and non-power-limited fire alarm conductors by at least 2 in. (50 mm), unless separated by a barrier or one wiring method is metal armor/raceway (725.55).

Article 760 splits fire alarm circuits into NPLFA (non-power-limited fire alarm) and PLFA (power-limited fire alarm); PLFA conductors must be listed as fire alarm cable and marked with the circuit type, NPLFA conductors follow Chapter 3 wiring methods.

PLFA circuits cannot be installed in the same raceway, cable, box, or enclosure with NPLFA, Class 1, or power conductors unless separated by a barrier or the conductors are all associated with the same system and listed for the purpose (760.139/760.154).

Article 800 covers communications circuits (telephone, data, CATV, network); 800.133 requires at least 2 in. (50 mm) separation between communications and power conductors, and communications cables cannot occupy the same raceway as Class 1 or power conductors.

Substitutions: a Class 2 cable may be substituted for a Class 3 cable only if the Class 2 cable is listed for Class 3 use; PLFA cable may be substituted for NPLFA only when the cable's ampacity and insulation rating meet the NPLFA requirements (760.154 exceptions).

Cable marking rules: PLFA cable is marked "PLFA" or "FPLP"; NPLFA cable is marked "NPLFA" or "FPLR"; riser-rated cable (FPLR) may be used in vertical shafts, plenum cable (FPLP) in environmental air spaces.

Article 725 Class 2/3 cables are marked "CL2" or "CL3" with a suffix (P for plenum, R for riser); these markings cannot substitute for FPLP/FPLR fire alarm listings in a fire alarm system.

Pathway classifications: Class A is a signaling line circuit or initiating device circuit with redundant paths so a single open or ground fault does not prevent alarm; Class B has a single path where a single fault causes loss of that portion; Class X requires both redundant paths and isolation of faults.

Class A circuits must be monitored for open and ground faults; Class B circuits must be monitored for open faults and (for initiating device circuits) for short circuits that would prevent alarm.

NFPA 72 requires that a single open, ground, or short fault on a Class B pathway not prevent the indication of alarm at the control unit for the remaining devices; Class A must survive a single fault and still operate all devices.

Signaling line circuit (SLC) loading: addressable devices per loop are limited by the manufacturer's listing and the control unit's power budget; NFPA 72 requires that the circuit be capable of operating all devices plus the required spare capacity.

Alarm signal transmission time: initiating device to notification appliance activation must not exceed 10 seconds for automatic alarm, 60 seconds when the alarm is transmitted to a supervising station, and 90 seconds for a proprietary supervising station.

Annunciation and display: the control unit must indicate alarm, supervisory, and trouble conditions visually and audibly; alarm takes priority over supervisory, and supervisory over trouble.

Circuit voltage drop: notification appliance circuits must be sized so the voltage at the last appliance is at least the appliance's listed minimum operating voltage (typically 85% of nameplate for 24 VDC appliances).

Ground fault detection is required for fire alarm circuits; a single ground fault on a Class A pathway must not prevent alarm operation, and the control unit must annunciate a ground fault trouble.

Smoke detector spacing: 30 ft (9.1 m) maximum spacing on smooth ceilings, with detectors placed within 21 ft (6.4 m) of any wall; spot-type detectors are spaced per the manufacturer's listed spacing, but NFPA 72 limits to 30 ft on smooth ceilings.

Heat detector spacing: 50 ft (15.2 m) maximum for fixed-temperature, 30 ft for rate-of-rise on smooth ceilings; detectors must be within 25 ft (7.6 m) of walls for 50 ft spacing.

Detectors must be at least 3 ft (0.9 m) from air supply diffusers and at least 4 in. (100 mm) from walls; on ceilings with beams deeper than 18 in., each bay is treated as a separate area requiring its own detector.

Duct smoke detectors are required for air handling systems over 2,000 cfm (0.94 m3/s) and must be installed in the return air duct; they are not a substitute for area smoke detection.

Manual pull stations must be located within 5 ft (1.5 m) of each exit door, mounted 42–48 in. (1.07–1.22 m) above the floor, and unobstructed; at least one per floor and one at each required exit.

Projected beam smoke detectors: spacing 60 ft (18.3 m) maximum, and the beam must be within 3 ft (0.9 m) of the ceiling for smooth ceilings unless listed otherwise.

Detector placement in corridors: smoke detectors spaced per smooth ceiling rules, but the corridor width may limit the effective spacing; detectors are required in corridors serving as part of the means of egress in many occupancies.

Initiating device circuits must be supervised; a single open on a Class B initiating device circuit must be annunciated as a trouble within 200 seconds (typical NFPA 72 requirement for supervised circuits).

Public mode audible alarm: at least 15 dBA above the ambient sound level, measured 5 ft (1.5 m) above the floor, or 5 dBA above ambient when ambient exceeds 105 dBA; minimum 65 dBA in occupied areas.

Private mode (e.g., sleeping rooms, hospital patient rooms) requires 10 dBA above ambient or 75 dBA minimum, whichever is greater, measured at the pillow level in sleeping areas.

Visible notification appliances: public mode requires 0.0375 candela per square foot of room area (0.0375 cd/ft²); private mode requires 0.0375 cd/ft² as well but with a minimum of 75 cd at the appliance.

Candela ratings and coverage: a 75 cd visible appliance covers a 20 ft × 20 ft room in public mode; a 110 cd covers 30 ft × 30 ft; a 177 cd covers 40 ft × 40 ft (per NFPA 72 Table 18.5.4.2.1).

Visible appliances must be mounted 80–96 in. (2.03–2.44 m) above the finished floor; in corridors, spacing is 15 ft (4.6 m) maximum between appliances and within 15 ft of the end of the corridor.

Audible appliances must be synchronized when installed in the same room or adjacent rooms; NFPA 72 requires synchronization of visible appliances and recommends it for audible appliances to avoid confusion.

Notification appliance circuit voltage drop: the last appliance must receive at least its listed minimum voltage; for 24 VDC systems this is typically 85% of rated voltage (e.g., 20.4 VDC for a 24 VDC appliance).

Temporal-3 pattern is the standard audible evacuation signal: 0.5 s on, 0.5 s off, three pulses, then 1.5 s off; it must be distinguishable from other signals.

Annual inspection/testing: all initiating devices, notification appliances, and control equipment must be tested at least annually; smoke detectors may be tested annually per NFPA 72 Table 14.3.1.

Monthly inspection: control unit, batteries, and trouble signals must be inspected monthly; the control unit must be checked for normal operation and any trouble conditions.

Battery testing: sealed lead-acid batteries must be tested annually for capacity; the battery must deliver 70% of its rated capacity after 4 hours (or the calculated load) to pass.

Smoke detector sensitivity testing: detectors must be tested for sensitivity within 1 year of installation and every 2 years thereafter if the manufacturer's listing permits; otherwise annually.

Documentation: NFPA 72 requires a written record of all inspections, tests, and maintenance, including the date, person performing, results, and any deficiencies corrected.

The record of completion (NFPA 72 Figure 7.8.2) must be completed at system acceptance and include the system description, device list, and certification by the installer.

Annual test of notification appliances: all audible and visible appliances must be tested annually for operation, and the sound pressure level must be verified in at least one location per area.

Pre-test notification: the building owner must be notified before testing, and the fire department must be notified if the system is connected to a supervising station, to avoid false alarms.

Protected premises systems include automatic fire alarm, manual fire alarm, and combination systems; they must be supervised and monitored for alarm, supervisory, and trouble conditions.

Supervising station types: central station (listed, with operator on duty), proprietary (owned by the property owner), remote supervising station (listed, off-site), and auxiliary (connects to municipal fire alarm system).

Central station systems must have a minimum of two independent means of communication (e.g., two phone lines, or one phone line plus a radio/cellular path) and must be listed.

Alarm transmission: the supervising station must receive and acknowledge the alarm within 90 seconds for a central station; retransmission to the fire department must occur within 90 seconds of receipt.

Emergency communications systems (ECS) include mass notification systems (MNS) and in-building fire emergency voice alarm communication systems (EVACS); intelligibility is required for voice systems (STI ≥ 0.50 in occupied areas).

Two-way emergency communications systems (e.g., area of refuge, elevator lobby) must be supervised and powered by the fire alarm system; the call must be answered within 30 seconds at the supervising station.

Supervisory signals (e.g., valve tamper, low air pressure) must be annunciated within 90 seconds and must not be confused with alarm signals; supervisory signals have lower priority than alarm.

Remote supervising station systems must be connected by a dedicated pathway or a listed communication method; loss of communication must be annunciated as a trouble at the protected premises.

Means of egress components: exit access, exit, and exit discharge; travel distance limits vary by occupancy (e.g., 250 ft for business occupancies in sprinklered buildings, 200 ft unsprinklered).

Occupant load: calculated by dividing floor area by the occupant load factor (e.g., 100 ft²/person for business, 15 ft²/person for assembly unconcentrated, 5 ft²/person for assembly concentrated).

Egress width: 0.2 in. per person for level components, 0.3 in. per person for stairs (or 0.15 in./0.2 in. for sprinklered buildings); minimum clear width is 28 in. for doors and 36 in. for corridors in most occupancies.

Two exits are required when occupant load exceeds 49 in most occupancies, or when travel distance exceeds the single-exit limit; exits must be remote from each other (at least half the diagonal of the room).

Fire alarm requirements: Group A (assembly), Group E (educational), Group I (institutional), Group R (residential with >16 units), and Group B (business) occupancies generally require a fire alarm system when the occupant load or building size exceeds thresholds.

Smoke detection is required in corridors and sleeping areas of Group R and I occupancies; in Group R-2, smoke alarms are required in each sleeping room and outside each sleeping area.

Emergency lighting and exit signs must be provided along the means of egress; exit signs must be illuminated and visible from any point in the corridor.

Group I-2 (hospitals, nursing homes) requires automatic sprinkler protection and smoke detection in corridors; evacuation capability is limited, so defend-in-place strategies apply.

Maine fire alarm work is regulated by the Office of the State Fire Marshal under Title 25 MRSA; alarm system contractors must be licensed by the State Fire Marshal's office.

Maine requires a Fire Alarm Systems Contractor license and individual installer/technician licensing; licensing includes examination and continuing education requirements.

Maine adopts NFPA 72 and NFPA 101 by reference through the Maine Fire Code (26 MRSA Chapter 3 and related rules); local amendments may apply in municipalities with local codes.

Plan review: fire alarm system plans must be submitted to the State Fire Marshal or local authority having jurisdiction (AHJ) for review before installation in most commercial occupancies.

Maine requires that fire alarm systems be installed and maintained by licensed personnel; unlicensed practice is subject to penalties under Title 25.

Maine's rules require notification to the AHJ before testing and after completion; a certificate of completion must be filed with the AHJ.

Maine licensing requires proof of insurance and a surety bond for contractors; individual technicians must work under a licensed contractor.

Continuing education: Maine requires license renewal (typically every 2 years) with documented continuing education hours in fire alarm and life safety topics.

Battery calculation formula: required capacity (Ah) = (standby current × standby hours + alarm current × alarm hours) × 1.25 (derating factor for aging and temperature).

NFPA 72 requires 24 hours of standby power followed by 5 minutes of alarm for commercial systems; for systems with a backup generator, 4 hours of standby may be permitted.

Secondary battery sizing: use the manufacturer's listed charging current and ensure the battery recharge time does not exceed 48 hours (or 24 hours for some systems) per NFPA 72.

Voltage drop calculation: VD = (2 × K × I × L) / CM, where K = 12.9 for copper, I = current in amperes, L = one-way length in feet, CM = circular mils of the conductor.

Notification appliance circuit sizing: total current draw of all appliances on a circuit must not exceed the circuit's rated capacity; each appliance's current draw is added, and voltage drop is calculated to the last device.

Wiring methods: fire alarm cable must be installed in raceway, cable tray, or surface raceway; PLFA cable must be supported every 4.5 ft (1.4 m) and within 12 in. of boxes.

Plan symbols: standard symbols include smoke detector (S), heat detector (H), pull station (P), horn (H), strobe (S), and the control panel; the riser diagram shows circuit routing and device addresses.

Load calculation: sum the standby current of all devices (panel, annunciators, communicators) and the alarm current of all notification appliances; compare to the panel's power supply rating with a 20% safety margin.