+---
+title: Mass Notification Systems
+category: Fire Protection
+toc_depth: 3
+description: >
+ When to use: In-building, wide-area, and distributed-recipient emergency communications systems (ECS) — commonly called mass notification systems (MNS) — that warn occupants and the public of fire and non-fire emergencies and instruct them on the appropriate protective action, in accordance with NFPA 72 Chapter 24. Covers the risk-analysis basis of design that establishes the need for and scope of an MNS; the autonomous control unit (ACU) and local operating consoles (LOC); in-building MNS using voice/alarm communications and visible notification and signage; wide-area MNS using high-power speaker arrays for outdoor and campus-scale coverage; distributed-recipient MNS using text, email, telephone, and mobile-app delivery, and interfaces to the public-alerting infrastructure (IPAWS, Wireless Emergency Alerts, and the Emergency Alert System); message prioritization and integration with the fire alarm system; voice intelligibility requirements and acceptance testing using the Speech Transmission Index and the Common Intelligibility Scale; pathway survivability; primary and secondary power; and commissioning and intelligibility testing. Typical applications include higher-education and K-12 campuses, healthcare and hospital campuses, military and federal facilities subject to UFC 4-021-01, high-rise and large assembly occupancies, transportation terminals, and corporate and industrial sites.
+ Not intended for: The fire alarm and signaling function itself — fire detection, the fire alarm control unit, initiating devices, and fire evacuation signaling are covered in [[sync/fire-alarm-systems]]; this standard governs the emergency communications and mass notification function that integrates with and, for emergency messages, takes priority over that fire alarm signaling. Not for standalone area-of-refuge two-way communication systems, elevator emergency phones, or firefighter telephone systems where no mass notification function is provided; not for routine background-music, paging, or commercial public-address systems that carry no emergency communications duty; not for the public safety in-building radio enhancement (DAS/BDA) systems used by responders — those are separate scopes. Wide-area public siren warning operated solely by a civil authority outside the protected premises is outside this scope except where it interfaces to an on-site MNS.
+---
+
+# Scope
+
+This standard covers the design documentation, equipment, installation, integration, testing, and commissioning of an emergency communications system (ECS), commonly referred to as a mass notification system (MNS), provided to warn the occupants of a building, the population of a site or campus, or a defined set of recipients of a fire or non-fire emergency and to instruct them on the protective action to take. The system shall comply with NFPA 72, National Fire Alarm and Signaling Code, Chapter 24 (Emergency Communications Systems), and, where the facility is a Department of Defense facility, with UFC 4-021-01, Design and O&M: Mass Notification Systems.
+
+A mass notification system differs fundamentally from a fire alarm system in purpose. A fire alarm system answers a single question — is there a fire — and produces a single fixed response: evacuate. A mass notification system addresses many hazards (fire, severe weather, hazardous-material release, active threat, infrastructure failure, and others) and conveys an intelligible, hazard-specific instruction that may be to evacuate, to shelter in place, to relocate, or to take some other action. Because the correct protective action for a non-fire emergency is frequently the opposite of fire evacuation — sheltering in place during a tornado or an external chemical release, for example — the emergency message of an MNS shall be able to take priority over the fire alarm evacuation signal. Establishing and managing that priority is one of the central requirements of this standard.
+
+The scope spans three architectures recognized by NFPA 72 Chapter 24, any combination of which may be required on a project: in-building MNS, which notifies the occupants inside a building or buildings; wide-area MNS, which notifies people outdoors and across a site, campus, or installation, typically using high-power speaker arrays; and distributed-recipient MNS (DRMNS), which delivers messages to individual recipients through text message, email, telephone, desktop alert, and mobile application. The scope includes the autonomous control unit (ACU) that originates and prioritizes messages, the local operating consoles (LOC) from which authorized personnel initiate live and pre-recorded messages, the notification appliances and speaker arrays, the visible notification and signage, the interfaces to the fire alarm system and to the public-alerting infrastructure (IPAWS, Wireless Emergency Alerts, and the Emergency Alert System), the pathway survivability provisions, and the primary and secondary power supplies.
+
+This standard is manufacturer-agnostic. Equipment is described by function and by the standard to which it is listed, never by brand name or product line. All work shall comply with the editions of NFPA 72, UFC 4-021-01, and other referenced documents adopted by the Authority Having Jurisdiction (AHJ); where the AHJ has adopted an earlier edition, the Contractor shall confirm the adopted edition in writing before design begins.
+
+# Referenced Standards
+
+Equipment, materials, design, and installation shall comply with the current adopted editions of the following standards and codes. Where requirements conflict, the more stringent shall govern unless the Engineer of Record directs otherwise in writing.
+
+| Standard | Title |
+|----------|-------|
+| NFPA 72 | National Fire Alarm and Signaling Code (Chapter 24 — Emergency Communications Systems) |
+| NFPA 70 | National Electrical Code (Article 760 — Fire Alarm Systems; Article 800 — Communications) |
+| NFPA 101 | Life Safety Code |
+| UFC 4-021-01 | Design and O&M: Mass Notification Systems (DoD facilities) |
+| UFC 4-010-01 | DoD Minimum Antiterrorism Standards for Buildings (establishes the MNS requirement for DoD) |
+| UL 864 | Standard for Control Units and Accessories for Fire Alarm Systems |
+| UL 2572 | Standard for Mass Notification Systems |
+| UL 1971 | Standard for Signaling Devices for the Hearing Impaired (visible notification) |
+| UL 1480 | Standard for Speakers for Fire Alarm, Emergency, and Commercial and Professional Use |
+| IBC Chapter 9 | International Building Code — Fire Protection Systems |
+| IFC Chapter 9 | International Fire Code — Fire Protection Systems (including emergency responder communications) |
+| ICC A117.1 | Accessible and Usable Buildings and Facilities |
+| ADA Standards for Accessible Design | Federal accessibility requirements for notification |
+| IEC 60268-16 | Objective rating of speech intelligibility by the Speech Transmission Index |
+| FEMA IPAWS | Integrated Public Alert and Warning System program requirements (Common Alerting Protocol) |
+| FCC 47 CFR Part 10 | Wireless Emergency Alerts (WEA) |
+
+# Risk Analysis and Basis of Design
+
+## Risk Analysis Required
+
+The basis of design for the mass notification system shall be a documented risk analysis prepared in accordance with NFPA 72 Chapter 24. Unlike a fire alarm system, whose scope is largely prescribed by the building code based on occupancy and area, the scope of a mass notification system is established by the risk analysis. The risk analysis is therefore the controlling design document and shall be completed and accepted by the Owner and the AHJ before the system is designed. No MNS scope, message set, coverage, or survivability requirement in this standard or on the drawings supersedes the conclusions of an accepted risk analysis.
+
+The risk analysis shall address both fire and non-fire emergencies, the nature and likelihood of the hazards to which the facility is exposed, the characteristics of the occupants (number, mobility, familiarity with the facility, and language), and the characteristics of the facility (construction, size, indoor and outdoor areas to be covered, and the time available to notify and move people). The detail and complexity of the risk analysis shall be commensurate with the complexity of the facility, and the analysis shall be based on the maximum occupant load of each occupiable space, area, building, or site to be covered.
+
+## Hazards Addressed
+
+The risk analysis shall identify the specific emergencies the system is required to address. The selected hazards determine the message set, the coverage architecture, and the prioritization logic that the rest of the design implements.
+
+```datasheet
+label: Emergencies Addressed by the MNS
+type: checkbox
+options:
+ - "Fire (integrated with the fire alarm system)"
+ - "Severe weather / tornado / shelter-in-place"
+ - "Hazardous material release (external or internal)"
+ - "Active threat / hostile event / lockdown"
+ - "Infrastructure failure / utility emergency"
+ - "Civil emergency / general all-hazards instruction"
+ - "Drill / test / all-clear messaging"
+default: "Fire (integrated with the fire alarm system)"
+```
+
+## System Architecture Selected
+
+The risk analysis and the areas requiring notification determine which of the three MNS architectures, or which combination, the project requires. A campus, for example, frequently requires all three: an in-building system for occupants of each building, a wide-area system for people outdoors, and a distributed-recipient system to reach individuals who are mobile or off-site.
+
+```datasheet
+label: MNS Architecture
+type: checkbox
+options:
+ - "In-building MNS (voice/alarm communications within buildings)"
+ - "Wide-area MNS (outdoor high-power speaker arrays / giant voice)"
+ - "Distributed-recipient MNS (text, email, phone, app, desktop alert)"
+ - "Interface to public alerting (IPAWS / WEA / EAS)"
+default: "In-building MNS (voice/alarm communications within buildings)"
+```
+
+## Emergency Response Plan
+
+The mass notification system shall implement an emergency response plan prepared by the Owner that defines, for each identified emergency, the message content, the areas or recipients to be notified, the order and priority of messages, the personnel authorized to initiate messages, and the action to be taken at the autonomous control unit versus a local operating console or a wide-area input. The emergency response plan is the source document for the message library and the prioritization matrix. The Contractor shall program the system to match the accepted emergency response plan and shall not invent message content or priority independently.
+
+# Submittals
+
+## Action Submittals
+
+The Contractor shall submit the following for the Engineer of Record's review and the AHJ's approval before procurement and before any installation begins. The mass notification submittal is a complete system-level engineering document; partial or piecemeal submittals shall be returned without review.
+
+- The accepted risk analysis and the Owner's emergency response plan, on which the design is based
+- Manufacturer's product data for every component: the autonomous control unit (ACU), all local operating consoles (LOC), amplifiers and power supplies, speakers and high-power speaker arrays, visible notification appliances, signage, the distributed-recipient platform, and all interface modules to the fire alarm system and to public alerting
+- Complete system shop drawings, including a riser diagram showing the ACU, every LOC, every amplifier and power supply, all speaker circuits and wide-area array sites, circuit class designations, and pathway survivability levels; and floor plans and site plans showing the location and coverage of every speaker, array, and visible appliance
+- The message prioritization matrix, in table form, showing every message source (fire alarm, ACU, each LOC, wide-area input, distributed-recipient platform, public-alerting input), every message type, and the resulting priority and arbitration outcome when sources conflict
+- An intelligibility design analysis identifying each acoustically distinguishable space (ADS) within the covered area, the design basis for achieving the required intelligibility in each ADS, and the proposed measurement locations for acceptance testing
+- Speaker layout and amplifier load calculations, and voice/voltage-drop calculations for each speaker circuit, confirming device operating level under worst-case load
+- Secondary-power (battery or other) calculations in accordance with NFPA 72, showing standby and alarm (emergency) load and the required capacity with the code-required margin
+- Listing documentation: UL 2572 for the mass notification system and UL 864 for control equipment used in the fire alarm interface, and listing of speakers, appliances, and power supplies to the applicable standards
+
+```datasheet
+label: Action Submittals Required
+type: checkbox
+options:
+ - "Risk analysis and emergency response plan"
+ - "Product data for all components"
+ - "System shop drawings (riser, floor plans, site plans)"
+ - "Message prioritization matrix"
+ - "Intelligibility design analysis (ADS identification)"
+ - "Speaker layout, amplifier load, and voltage-drop calculations"
+ - "Secondary-power (battery) calculations per NFPA 72"
+ - "Listing documentation (UL 2572, UL 864, UL 1480, UL 1971)"
+default: "Risk analysis and emergency response plan"
+```
+
+## Closeout Submittals
+
+At substantial completion, prior to system acceptance, the Contractor shall submit:
+
+- The signed acceptance test report, including the voice intelligibility test report (STI or CIS measurements per ADS) and the message prioritization verification, witnessed by the AHJ where required
+- As-built system drawings reflecting all changes, including final speaker and array locations, final circuit designations, and final array site GPS coordinates for wide-area systems
+- The complete ACU and LOC programming record, including the message library, the recipient and zone groups, the prioritization configuration, and all user accounts and access levels
+- The recorded emergency message library (audio files and text templates) as installed
+- Operation and maintenance data, including operating procedures for each message type, the procedure to initiate a live message from each LOC, the test and inspection schedule per NFPA 72 Chapter 14, and the procedure to issue and to retract a distributed-recipient or public alert
+- Warranty documentation
+
+```datasheet
+label: Closeout Submittals Required
+type: checkbox
+options:
+ - "Acceptance test report with intelligibility results"
+ - "As-built drawings with array GPS coordinates"
+ - "ACU and LOC programming record"
+ - "Recorded emergency message library (as installed)"
+ - "Operation and maintenance data"
+ - "Warranty documentation"
+default: "Acceptance test report with intelligibility results"
+```
+
+# Quality Assurance
+
+## Contractor and Designer Qualifications
+
+The mass notification system shall be designed by a person qualified in emergency communications system design — a licensed Professional Engineer with demonstrated ECS/MNS experience, or a designer holding NICET certification in Fire Alarm Systems or the equivalent at the level required by the AHJ. The installing contractor shall hold the fire alarm or low-voltage license required by the state or local jurisdiction and shall demonstrate manufacturer-authorized training on the specific ACU and MNS platform installed. For DoD facilities, personnel qualifications shall additionally meet UFC 4-021-01.
+
+```datasheet
+label: Designer Qualification Basis
+type: radio
+options:
+ - "Licensed Professional Engineer (ECS/MNS design) + NICET-certified installer"
+ - "NICET Fire Alarm Systems Level III designer + Level II installer-in-charge"
+ - "As accepted by AHJ — submit documentation for review"
+default: "Licensed Professional Engineer (ECS/MNS design) + NICET-certified installer"
+```
+
+## Listing Requirements
+
+The mass notification system equipment shall be listed to UL 2572, Standard for Mass Notification Systems. Where the MNS shares equipment with, or interfaces to, the fire alarm system, the shared control equipment shall additionally be listed to UL 864 for fire alarm service. Speakers used for emergency voice notification shall be listed to UL 1480, and visible notification appliances shall be listed to UL 1971. All devices shall be listed for use with the ACU platform and shall appear on the manufacturer's compatibility list; unlisted or incompatible devices shall not be installed.
+
+## Coordination
+
+A pre-installation conference shall be held with the MNS Contractor, the fire alarm Contractor, the electrical contractor, the network/IT representative (for distributed-recipient and IP interfaces), the Owner's emergency manager, and the AHJ. The message prioritization matrix and the emergency response plan shall be reviewed and approved at this meeting. Because the MNS message takes priority over fire alarm signaling, the interface between the two systems shall be jointly reviewed by both contractors and accepted by the AHJ before installation.
+
+# System Control Architecture
+
+## Autonomous Control Unit
+
+The mass notification system shall be controlled by an autonomous control unit (ACU) that originates, schedules, prioritizes, and monitors all emergency messages and that supervises the notification network in accordance with NFPA 72 Chapter 24. The ACU is the single authority for the notification appliance network it serves. Unless the emergency response plan directs otherwise, actions taken at the ACU shall take precedence over actions taken at any remote location, including a local operating console or an input from a wide-area MNS. Where more than one ACU can control the same notification network, only one ACU shall be in control at any given time, and the means of transferring control shall be defined and supervised.
+
+```datasheet
+label: ACU Type
+type: radio
+options:
+ - "Combination fire alarm / MNS control unit (UL 864 + UL 2572 listed)"
+ - "Dedicated MNS ACU interfaced to a separate fire alarm control unit"
+ - "Networked ACUs with defined single point of control (campus / multi-building)"
+drawing_ref: true
+default: "Combination fire alarm / MNS control unit (UL 864 + UL 2572 listed)"
+```
+
+The ACU shall be monitored for integrity: loss of primary power, secondary-power fault, loss of communication with any controlled node, and any circuit fault shall generate a trouble signal that is annunciated at the ACU and, where the MNS is integrated with the fire alarm system, transmitted to the supervising station in accordance with [[sync/fire-alarm-systems]].
+
+## Local Operating Console
+
+A local operating console (LOC) is the interface from which authorized personnel select and initiate pre-recorded messages and deliver live voice messages to selected zones or to the entire system. An LOC shall be provided at each location required by the emergency response plan and the AHJ — commonly at a constantly attended location, a security or command center, and the fire command center where one is required. The LOC shall provide a microphone for live voice paging, controls to select message and zone, and a visual indication of system status and of which messages are active.
+
+```datasheet
+label: Local Operating Consoles Provided
+type: checkbox
+options:
+ - "Fire command center / fire department interface location"
+ - "Constantly attended location (security desk / front desk)"
+ - "Emergency operations / command center"
+ - "Police or campus dispatch"
+ - "Per emergency response plan and AHJ (see drawings)"
+default: "Fire command center / fire department interface location"
+```
+
+The LOC shall be secured against unauthorized use by keyswitch, credential, or passcode as required by the emergency response plan. Live voice from an LOC, when authorized by the prioritization logic, shall override pre-recorded messages so that responders can give real-time instructions.
+
+## Message Prioritization
+
+The system shall arbitrate among competing message sources according to a documented prioritization matrix derived from the emergency response plan, in accordance with NFPA 72 Chapter 24. Because a non-fire emergency may require occupants to remain in place while the fire alarm system is signaling evacuation, an authorized mass notification message shall, when the emergency response plan so provides, take priority over the fire alarm evacuation signal — both live voice and pre-recorded MNS messages typically take priority over fire evacuation signaling. When the MNS takes control of the notification appliances for an emergency message, that condition shall be supervised and annunciated so that responders know the fire signal has been overridden.
+
+```datasheet
+label: Message Priority Order (highest first)
+type: select
+options:
+ - "Live voice (authorized LOC) > pre-recorded MNS emergency > fire alarm evacuation > supervisory/trouble > routine/test"
+ - "Pre-recorded MNS emergency > fire alarm evacuation > live voice > routine (where ERP requires automated priority)"
+ - "Per emergency response plan prioritization matrix on drawings"
+drawing_ref: true
+default: "Live voice (authorized LOC) > pre-recorded MNS emergency > fire alarm evacuation > supervisory/trouble > routine/test"
+```
+
+The prioritization logic shall be deterministic: when two sources contend, the outcome shall be defined and repeatable, and the lower-priority message shall be queued or suppressed, not garbled with the higher-priority message. The prioritization matrix shall be verified during acceptance testing.
+
+## Fire Alarm System Integration
+
+The mass notification system shall integrate with the fire alarm system covered by [[sync/fire-alarm-systems]]. The fire alarm system continues to perform fire detection and to transmit alarm, supervisory, and trouble signals to the supervising station; the mass notification system controls occupant messaging and, for emergency messages, takes priority over the fire alarm evacuation signal as established by the prioritization matrix. The interface shall be supervised so that a fault in the interface generates a trouble signal, and the integration shall be arranged so that a failure of the MNS does not impair the fire alarm system's required detection and signaling functions.
+
+```datasheet
+label: Fire Alarm Integration Method
+type: radio
+options:
+ - "Shared combination control unit (single platform, UL 864 + UL 2572)"
+ - "Supervised hardwired interface between separate FACU and ACU"
+ - "Listed network interface between separate fire alarm and MNS platforms"
+drawing_ref: true
+default: "Shared combination control unit (single platform, UL 864 + UL 2572)"
+```
+
+# In-Building Mass Notification
+
+## Voice Notification
+
+In-building mass notification shall be provided by an emergency voice/alarm communications system delivering intelligible voice messages, supplemented by visible notification, throughout the areas identified by the risk analysis. The voice system shall deliver pre-recorded messages automatically on the appropriate input and shall allow authorized live voice paging from a local operating console. The voice notification shall comply with the audibility requirements of NFPA 72 Chapter 18 and the intelligibility requirements of Chapter 24.
+
+```datasheet
+label: In-Building Voice System Capability
+type: radio
+options:
+ - "Pre-recorded messages + live voice paging from LOC"
+ - "Pre-recorded messages only (no live paging)"
+ - "Live paging only (legacy / limited application)"
+default: "Pre-recorded messages + live voice paging from LOC"
+```
+
+## Speakers
+
+Emergency voice speakers shall be listed to UL 1480 and shall be selected and located to achieve the required sound pressure level and intelligibility in each space. The speaker tap setting (power) shall be selected for the acoustic conditions of the space; high-ceiling, hard-surfaced, and reverberant spaces require careful tap selection and speaker spacing to achieve intelligibility, not merely audibility. Speaker spacing and tap settings shall be shown on the floor plans and supported by the intelligibility design analysis.
+
+```datasheet
+label: Speaker Type
+type: select
+options:
+ - "Ceiling speaker (lay-in or recessed) — typical occupied rooms and corridors"
+ - "Wall speaker — corridors and spaces without accessible ceiling"
+ - "Speaker/strobe combination (voice + visible)"
+ - "Horn-type / projector speaker — high-noise or high-ceiling spaces"
+ - "Pendant speaker — open high-ceiling areas (atria, gymnasia)"
+default: "Ceiling speaker (lay-in or recessed) — typical occupied rooms and corridors"
+```
+
+```datasheet
+label: Speaker Tap Setting
+type: select
+unit: W
+options:
+ - "1/4 W"
+ - "1/2 W"
+ - "1 W"
+ - "2 W"
+ - "Per intelligibility design and ambient survey — see drawings"
+drawing_ref: true
+default: "Per intelligibility design and ambient survey — see drawings"
+```
+
+## Audibility
+
+Emergency voice messages shall be audible above ambient sound: the message shall produce a sound pressure level at least 15 dB above the average ambient sound pressure level or 5 dB above the maximum ambient level, whichever is greater, in accordance with NFPA 72. Audibility is necessary but not sufficient — a message that is loud but unintelligible does not communicate the instruction. The design shall satisfy both audibility and the intelligibility requirements below.
+
+```datasheet
+label: Audible Sound Pressure Basis
+type: radio
+options:
+ - "15 dB above average ambient (standard occupied spaces)"
+ - "5 dB above maximum ambient (intermittent high-noise spaces)"
+ - "Per ambient sound survey — see drawings"
+drawing_ref: true
+default: "15 dB above average ambient (standard occupied spaces)"
+```
+
+## Visible Notification
+
+Visible notification appliances shall be provided to supplement audible notification for occupants who are deaf or hard of hearing and in spaces where audible notification alone is insufficient, in accordance with NFPA 72 Chapter 18, ICC A117.1, and the ADA Standards. Where a visible appliance is used for both fire and mass notification, the means of distinguishing a mass notification signal from a fire alarm signal shall be defined; NFPA 72 Chapter 24 permits text and graphic displays and supplementary visible signals to convey non-fire messages. Strobes used for fire alarm signaling shall continue to comply with the synchronization requirements of [[sync/fire-alarm-systems]].
+
+```datasheet
+label: Visible Notification for MNS
+type: checkbox
+options:
+ - "Strobes (shared with fire alarm, distinguished by message)"
+ - "Textual signs / message boards (LED or LCD)"
+ - "Graphic / digital signage interface"
+ - "Supplementary colored / amber visible signals for non-fire events"
+default: "Strobes (shared with fire alarm, distinguished by message)"
+```
+
+## Textual and Visible Signage
+
+Where the risk analysis or the emergency response plan calls for visible text, the system shall provide listed textual or graphic message displays in the covered areas. Text signage is especially valuable in high-noise environments and for hearing-impaired occupants, and for conveying detailed instructions that voice alone cannot. Message displays shall present the same instruction as the voice and distributed-recipient messages for the same event so that occupants receive a consistent instruction across all channels.
+
+# Wide-Area Mass Notification
+
+## Application
+
+Where the risk analysis requires notification of people outdoors and across a site, campus, or installation, a wide-area mass notification system shall be provided. Wide-area MNS — sometimes called "giant voice" — uses high-power speaker arrays mounted on poles, towers, or building exteriors to deliver intelligible voice and tone signals across large outdoor areas. For DoD facilities the wide-area MNS shall comply with UFC 4-021-01.
+
+```datasheet
+label: Wide-Area MNS Required
+type: radio
+options:
+ - "No — in-building and/or distributed-recipient only"
+ - "Yes — outdoor high-power speaker arrays (see site plan)"
+drawing_ref: true
+default: "No — in-building and/or distributed-recipient only"
+```
+
+## High-Power Speaker Arrays
+
+Each high-power speaker array (HPSA) site shall provide the coverage and intelligibility required by the design over its assigned area. The array site shall include a local control unit, amplification, a power supply with secondary (battery) power and charger, the communication link to the ACU (wired or supervised radio), the array structure (pole, tower, or building mount), and the loudspeaker assembly. Array locations shall be established by a joint site survey of the installing Contractor and the Owner, recorded with GPS coordinates, and verified before supporting structures are installed.
+
+```datasheet
+label: HPSA Site Communication Link
+type: radio
+options:
+ - "Wired (fiber or copper) supervised link to ACU"
+ - "Supervised radio link to ACU"
+ - "Dual-path (wired primary + radio backup)"
+drawing_ref: true
+default: "Supervised radio link to ACU"
+```
+
+```datasheet
+label: HPSA Array Mounting
+type: select
+options:
+ - "Dedicated pole"
+ - "Existing tower / structure"
+ - "Building rooftop / facade"
+ - "Per site survey and GPS-recorded locations on site plan"
+drawing_ref: true
+default: "Per site survey and GPS-recorded locations on site plan"
+```
+
+## Outdoor Coverage and Intelligibility
+
+The wide-area system shall achieve intelligible voice coverage over the outdoor areas defined by the risk analysis. Outdoor intelligibility is governed by array spacing, height, directivity, terrain, building shadowing, and ambient noise; the design shall account for these and shall avoid the time-delay and echo effects of overlapping coverage from distant arrays, which destroy intelligibility. Tone-only signaling (an alert tone or siren) may be used to gain attention before a voice message but shall not substitute for the intelligible voice instruction where the risk analysis requires voice.
+
+```datasheet
+label: Wide-Area Signal Content
+type: radio
+options:
+ - "Alert tone followed by intelligible voice message"
+ - "Intelligible voice message only"
+ - "Tone / siren only (where risk analysis does not require voice)"
+default: "Alert tone followed by intelligible voice message"
+```
+
+# Distributed-Recipient Mass Notification
+
+## Application
+
+Where the risk analysis requires reaching individuals directly — including occupants who are mobile, off-site, or in areas not covered by in-building or wide-area notification — a distributed-recipient mass notification system (DRMNS) shall be provided. A DRMNS delivers a message to a list of recipients over telecommunications and data networks: text (SMS) message, email, telephone (voice) call, desktop alert, and mobile-application push notification. A DRMNS is a targeted, opt-in or roster-based system distinct from the broadcast public-alerting systems described below.
+
+```datasheet
+label: Distributed-Recipient Delivery Channels
+type: checkbox
+options:
+ - "SMS / text message"
+ - "Email"
+ - "Telephone (automated voice call)"
+ - "Mobile application push notification"
+ - "Desktop / workstation alert"
+ - "Social media / website integration"
+default: "SMS / text message"
+```
+
+## Recipient Management
+
+The distributed-recipient platform shall manage recipient lists, groups, and roles so that a message can be targeted to the appropriate population — an entire organization, a building, a department, or a defined response team. The platform shall support recipient self-registration where the Owner's policy uses opt-in subscription, and roster import where the Owner maintains the recipient list. Delivery shall be confirmed and reported where the channel supports it, so the Owner can determine who was reached.
+
+```datasheet
+label: Recipient Enrollment Model
+type: radio
+options:
+ - "Opt-in self-registration (subscribers provide contact info)"
+ - "Owner-maintained roster (import from directory / HR system)"
+ - "Hybrid (roster plus opt-in for non-roster recipients)"
+default: "Owner-maintained roster (import from directory / HR system)"
+```
+
+## Public Alerting Interface
+
+Where the emergency response plan requires reaching the general public in and around the facility, the system shall interface to the public-alerting infrastructure. The Integrated Public Alert and Warning System (IPAWS), operated by FEMA, distributes a single authenticated alert across multiple channels using the Common Alerting Protocol, including Wireless Emergency Alerts (WEA) to mobile devices in a geographic area and the Emergency Alert System (EAS) over radio and television. WEA reaches capable mobile devices in the target area without prior subscription, which makes it valuable for reaching visitors and transient populations that an opt-in roster cannot. Initiating IPAWS/WEA/EAS alerts requires that the originating authority be a FEMA-authorized alerting authority; the system shall be configured to send to IPAWS only under the credentials and approval workflow established by the Owner's authorized alerting authority.
+
+```datasheet
+label: Public Alerting Interface
+type: checkbox
+options:
+ - "IPAWS (Common Alerting Protocol gateway)"
+ - "Wireless Emergency Alerts (WEA) via IPAWS"
+ - "Emergency Alert System (EAS) via IPAWS"
+ - "None — internal distributed-recipient notification only"
+default: "None — internal distributed-recipient notification only"
+```
+
+The distributed-recipient and public-alerting channels supplement, and do not replace, the in-building and wide-area notification required to protect occupants who are present in the covered area. A text message is not a substitute for an intelligible voice instruction to occupants who must act immediately.
+
+# Voice Intelligibility
+
+## Intelligibility Requirement
+
+Where the mass notification system conveys voice messages, the voice shall be intelligible — occupants shall be able to understand the words, not merely hear that an announcement is being made. Intelligibility is a pass/fail design and acceptance requirement under NFPA 72 Chapter 24, not merely a design aspiration. If the installed system does not achieve the required intelligibility, additional or relocated speakers, signal processing, or acoustic treatment shall be provided until it does.
+
+## Acoustically Distinguishable Spaces
+
+The covered area shall be divided into acoustically distinguishable spaces (ADS) for the purpose of designing and verifying intelligibility. An ADS is a space that is physically defined, or that differs from adjacent spaces in its acoustic, environmental, or use characteristics — reverberation time, ambient noise, ceiling height, or surface finish. The intelligibility design analysis shall identify each ADS in the covered area and shall designate each ADS as one in which intelligibility is required or one in which intelligibility is not required (for example, a small mechanical closet where occupant instruction is not needed). The basis for any ADS designated as not requiring intelligibility shall be documented and accepted.
+
+```datasheet
+label: Intelligibility Required Throughout
+type: radio
+options:
+ - "Yes — all occupiable ADS require verified intelligibility"
+ - "Selected ADS exempt — exemptions documented and accepted by AHJ"
+drawing_ref: true
+default: "Yes — all occupiable ADS require verified intelligibility"
+```
+
+## Intelligibility Metric and Criteria
+
+Intelligibility shall be quantified using the Speech Transmission Index (STI), per IEC 60268-16, or its representation on the Common Intelligibility Scale (CIS). Where quantitative measurement is performed, the system shall be considered acceptable in an ADS when at least 90 percent of the measurement locations within that ADS achieve an STI of not less than 0.45 (0.65 CIS) and the average of the measurement locations achieves an STI of not less than 0.50 (0.70 CIS), in accordance with NFPA 72 Chapter 24 and its annex guidance. A qualitative listening assessment is permitted by the code in lieu of quantitative measurement; however, quantitative STI/CIS measurement is the preferred and more defensible method and shall be used where the AHJ, the Owner, or the risk analysis requires it.
+
+```datasheet
+label: Intelligibility Verification Method
+type: radio
+options:
+ - "Quantitative STI / CIS measurement (preferred)"
+ - "Qualitative listening assessment (where permitted by AHJ)"
+ - "As required by AHJ"
+default: "Quantitative STI / CIS measurement (preferred)"
+```
+
+```datasheet
+label: Minimum STI per Measurement Location
+type: range
+unit: STI
+options:
+ min: 0.40
+ max: 0.70
+ setpoints: [0.40, 0.45, 0.50, 0.60, 0.70]
+default: 0.45
+```
+
+```datasheet
+label: Minimum Average STI per ADS
+type: range
+unit: STI
+options:
+ min: 0.45
+ max: 0.70
+ setpoints: [0.45, 0.50, 0.60, 0.70]
+default: 0.50
+```
+
+# Circuits, Pathways, and Survivability
+
+## Circuit Classes
+
+Mass notification circuits shall be designed and installed in accordance with the class designations of NFPA 72 Chapter 12. The circuit class determines how the circuit behaves under a wiring fault. The required class is determined by the risk analysis and the notification strategy.
+
+```datasheet
+label: Speaker / Notification Circuit Class
+type: radio
+options:
+ - "Class A (fault-tolerant loop — single open or ground fault survives)"
+ - "Class B (radial / T-tap — single open disables the downstream segment)"
+ - "Class X (enhanced — survives open and short on a redundant path)"
+drawing_ref: true
+default: "Class A (fault-tolerant loop — single open or ground fault survives)"
+```
+
+```datasheet
+label: Control / Data Network Class
+type: radio
+options:
+ - "Class A or Class X redundant network between ACU, LOC, and nodes"
+ - "Class B network (where accepted by risk analysis and AHJ)"
+drawing_ref: true
+default: "Class A or Class X redundant network between ACU, LOC, and nodes"
+```
+
+## Pathway Survivability
+
+Pathway survivability is the degree to which the MNS circuits maintain functional integrity during a fire or other emergency. The required pathway survivability level shall be determined by the risk analysis in accordance with NFPA 72 Chapter 24 and Section 12.4 — the survivability requirement for a mass notification system is set by the risk analysis, considering both fire and non-fire events, rather than prescribed solely by occupancy. Survivability provisions shall ensure that the system can continue to deliver messages to areas not yet affected by the emergency for the time required by the emergency response plan.
+
+```datasheet
+label: Pathway Survivability Level
+type: select
+options:
+ - "Level 0 — no survivability requirement (risk analysis basis)"
+ - "Level 1 — protected by 2-hour fire-rated assembly or equivalent"
+ - "Level 2 — circuit-integrity (CI) cable or metallic conduit in 2-hour construction"
+ - "Level 3 — listed 2-hour fire-rated cable system"
+ - "Per risk analysis and AHJ (see drawings)"
+drawing_ref: true
+default: "Per risk analysis and AHJ (see drawings)"
+```
+
+# Power Supplies and Secondary Power
+
+## Primary Power
+
+The ACU and each amplifier, power supply, LOC, and wide-area array site shall be supplied from a primary power source in accordance with NFPA 72 and NEC Article 760. In-building MNS control equipment shall be served by a dedicated branch circuit, identified and labeled, coordinated with [[sync/fire-alarm-systems]] where the MNS shares the fire alarm power arrangement. The Contractor shall provide the connected-load calculation to the electrical engineer of record for verification.
+
+```datasheet
+label: Primary Power Supply Voltage
+type: radio
+options:
+ - "120V, single-phase, 60 Hz (standard)"
+ - "208V / 240V, single-phase, 60 Hz (large amplifier banks)"
+ - "Per drawings"
+drawing_ref: true
+default: "120V, single-phase, 60 Hz (standard)"
+```
+
+## Secondary Power
+
+Each component shall be provided with secondary power so that the system continues to operate on loss of primary power, in accordance with NFPA 72. The secondary supply shall support the system in standby for the required standby period and shall then deliver the full emergency (alarm) load for the required emergency-operation period. For voice/emergency communications systems, the secondary supply shall support full emergency operation for 15 minutes following a 24-hour standby period; longer durations apply where the risk analysis, the AHJ, or UFC 4-021-01 requires them. Battery capacity shall be calculated with the margin required by the adopted edition of NFPA 72, and the calculation shall be submitted.
+
+```datasheet
+label: Secondary Power Duration
+type: radio
+options:
+ - "24 hours standby + 15 minutes emergency operation (standard voice/ECS)"
+ - "24 hours standby + 30 minutes emergency operation (enhanced)"
+ - "60 hours standby + 15 minutes emergency operation (essential facility)"
+ - "Per risk analysis / UFC 4-021-01 (see drawings)"
+drawing_ref: true
+default: "24 hours standby + 15 minutes emergency operation (standard voice/ECS)"
+```
+
+```datasheet
+label: Secondary Power Source
+type: radio
+options:
+ - "Sealed VRLA (valve-regulated lead-acid) batteries — standard"
+ - "Batteries supplemented by standby generator (extended duration)"
+ - "Per drawings"
+drawing_ref: true
+default: "Sealed VRLA (valve-regulated lead-acid) batteries — standard"
+```
+
+Each wide-area array site shall have its own secondary power sized for the same standby-plus-emergency duration, because an array site is remote and may lose primary power independently of the central equipment.
+
+# Installation
+
+## General
+
+The Contractor shall install the system in accordance with this standard, the approved shop drawings, NFPA 72, NEC Article 760 and Article 800, UFC 4-021-01 where applicable, and the manufacturer's instructions. Where these conflict, the more stringent governs. The MNS shall be installed so that its required functions, and the required functions of any integrated fire alarm system, are not impaired by the installation of the other.
+
+## Wiring Methods
+
+In-building MNS speaker and control wiring shall use cable types and raceways appropriate to the circuit classification of NEC Article 760 and the pathway survivability level required. Emergency voice circuits shall not share raceway with non-emergency power circuits. Where pathway survivability is required, the wiring method — cable type and raceway — shall be a listed assembly evaluated for the required level, and the Contractor shall confirm compliance before purchasing materials. Conduit and raceway installation shall coordinate with [[sync/raceways-and-conduit]].
+
+```datasheet
+label: Speaker Circuit Wiring Method
+type: select
+options:
+ - "FPL cable in EMT (power-limited, non-plenum)"
+ - "FPLP cable in EMT (power-limited, plenum)"
+ - "FPLR cable in EMT (power-limited, riser)"
+ - "Circuit-integrity (CI) / fire-rated cable (survivability applications)"
+drawing_ref: true
+default: "FPL cable in EMT (power-limited, non-plenum)"
+```
+
+## Wide-Area Array Installation
+
+Wide-area speaker array structures shall be installed at the GPS-verified locations established by the joint site survey, on foundations and supports designed for the wind and ice loads of the site. Array control cabinets shall be weatherproof and listed for the outdoor environment. Radio links, where used, shall be installed and aimed for a reliable supervised path to the ACU, and the link shall be tested for signal margin before acceptance.
+
+## Identification and Labeling
+
+The ACU, each LOC, each amplifier and power supply, and each array control cabinet shall be permanently labeled identifying its function. Where the MNS shares equipment with the fire alarm system, labeling shall make clear which functions are mass notification and which are fire alarm. Circuit breakers serving MNS equipment shall be identified and labeled against accidental disconnection.
+
+# Testing and Commissioning
+
+## Acceptance Test
+
+The complete system shall be tested and commissioned at acceptance in accordance with NFPA 72 Chapter 14 and Chapter 24, UFC 4-021-01 where applicable, and witnessed by the AHJ where required. The acceptance test shall verify every message source and message, the prioritization matrix, the integration with the fire alarm system, the audibility and intelligibility of voice notification, the visible notification, the distributed-recipient and public-alerting delivery, the supervision and trouble reporting of all circuits and nodes, and the secondary-power operation. Testing shall not be scheduled until the Contractor has completed a full pre-test with its own personnel.
+
+```datasheet
+label: Acceptance Test Scope
+type: checkbox
+options:
+ - "All pre-recorded messages and live voice from each LOC verified"
+ - "Message prioritization matrix verified (including MNS-over-fire priority)"
+ - "Fire alarm integration and supervision verified"
+ - "Audibility (sound pressure) verified per zone"
+ - "Voice intelligibility (STI/CIS) verified per ADS"
+ - "Visible notification and signage verified"
+ - "Distributed-recipient delivery verified (each channel)"
+ - "Public alerting (IPAWS/WEA/EAS) interface verified (test message)"
+ - "Secondary-power operation verified"
+default: "Message prioritization matrix verified (including MNS-over-fire priority)"
+```
+
+## Message Prioritization Test
+
+The prioritization matrix shall be verified by simultaneously presenting contending message sources and confirming that the system resolves the contention deterministically per the accepted matrix. The test shall specifically confirm that an authorized mass notification emergency message takes priority over the fire alarm evacuation signal where the emergency response plan so requires, and that the override is supervised and annunciated.
+
+## Intelligibility Test
+
+Voice intelligibility shall be verified at acceptance for every ADS in which intelligibility is required. Where quantitative verification is used, measurements shall be taken with a calibrated STI/CIS measurement system at representative locations within each ADS, and the results shall meet the per-location and per-ADS criteria stated above. The intelligibility test report shall identify each ADS, the measurement locations, the measured values, and the pass/fail determination, and shall be included in the acceptance test submittal. Where an ADS fails, corrective measures shall be applied and the ADS retested until it passes.
+
+```datasheet
+label: Intelligibility Test Coverage
+type: radio
+options:
+ - "Every ADS requiring intelligibility measured"
+ - "Representative sampling of ADS by type (where accepted by AHJ)"
+ - "Qualitative listening test (where permitted)"
+default: "Every ADS requiring intelligibility measured"
+```
+
+## Distributed-Recipient and Public-Alerting Test
+
+The distributed-recipient platform shall be tested by sending a test message over each configured channel to a test group and confirming delivery and delivery reporting. Where a public-alerting interface is configured, an end-to-end test of the IPAWS/WEA/EAS path shall be coordinated with the Owner's authorized alerting authority and FEMA as required, using the designated test procedure, so that a live public alert is never inadvertently issued during testing.
+
+# Delivery, Storage, and Handling
+
+Equipment shall be delivered in the manufacturer's original packaging, stored in a clean, dry, conditioned space within the manufacturer's environmental limits, and protected from physical damage, moisture, and dust until installed. Wide-area array electronics and outdoor enclosures shall be protected from weather until permanently installed and energized. Batteries shall be stored charged and within their temperature limits and shall be placed in service before their shelf-life charge is depleted.
+
+# Warranty
+
+The Contractor shall warrant the mass notification system installation against defects in materials and workmanship for a period of not less than 12 months from the date of system acceptance, or for the longer period stated in the contract documents. During the warranty period the Contractor shall respond to system troubles within the time stated in the contract and shall correct, at no cost to the Owner, any defect in the control equipment, speakers, arrays, visible appliances, wiring, programming, or interfaces, including any deficiency that causes the system to fail to meet the audibility or intelligibility requirements established at acceptance.
+
+```datasheet
+label: Warranty Period
+type: select
+options:
+ - "1 year from date of system acceptance"
+ - "2 years from date of system acceptance"
+ - "Per manufacturer's warranty document — see closeout submittal"
+default: "1 year from date of system acceptance"
+```
+
+# Inspection, Testing, and Maintenance
+
+After acceptance, the Owner shall maintain the mass notification system in accordance with NFPA 72 Chapter 14 and, for DoD facilities, UFC 4-021-01. The maintenance program shall include periodic inspection of all components, periodic functional testing of message sources, prioritization, and notification, periodic verification of secondary power, periodic confirmation of distributed-recipient and public-alerting connectivity, and battery replacement on the manufacturer's schedule. Intelligibility shall be re-verified after any change to the building acoustics, the speaker layout, or the message content that could affect it.
+
+```datasheet
+label: Inspection and Testing Frequency
+type: radio
+options:
+ - "Per NFPA 72 Chapter 14 minimum (annual functional test)"
+ - "Quarterly functional test (enhanced / high-occupancy)"
+ - "Per UFC 4-021-01 (DoD facilities)"
+ - "Per Owner's maintenance contract with listed contractor"
+default: "Per NFPA 72 Chapter 14 minimum (annual functional test)"
+```