Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
---
title: Public Address and Paging Systems
category: Electrical
toc_depth: 3
description: >
− When to use: centralized amplifier-based or IP-networked audio distribution
− for routine announcements, background music, general intercom, and zone-based
− paging across buildings and campuses (schools, universities, offices,
− industrial facilities, warehouses, healthcare campuses, correctional
− facilities, and transportation terminals). Covers system architecture
− (70-volt constant-voltage analog vs. IP-networked audio), master and remote
− paging stations, amplifiers and digital signal processors, loudspeakers,
− supervision, intelligibility, and the interface to fire alarm voice
− evacuation.
− Not intended for: life-safety voice evacuation and emergency mass
− notification triggered by a fire alarm panel (use
− [[sync/mass-notification-systems]] and [[sync/fire-alarm-systems]] for the
− NFPA 72 Chapter 24 Emergency Communications System); fire alarm initiating
− devices and listed control units ([[sync/fire-alarm-systems]]); backbone
− pathways, conduit fill, and telecom rooms ([[sync/structured-cabling]]);
− cellular and public-safety radio coverage
− ([[sync/distributed-antenna-systems]]); security and access-control
− entrance intercoms; and auditorium sound reinforcement or AV presentation
− systems.
+ When to use: centralized amplifier-based or IP-networked audio distribution for routine announcements, background music, general intercom, and zone-based paging across buildings and campuses (schools, universities, offices, industrial facilities, warehouses, healthcare campuses, correctional facilities, and transportation terminals). Covers system architecture (70-volt constant-voltage analog vs. IP-networked audio), master and remote paging stations, amplifiers and digital signal processors, loudspeakers, supervision, intelligibility, and the interface to fire alarm voice evacuation.
+ Not intended for: life-safety voice evacuation and emergency mass notification triggered by a fire alarm panel (use [[sync/mass-notification-systems]] and [[sync/fire-alarm-systems]] for the NFPA 72 Chapter 24 Emergency Communications System); fire alarm initiating devices and listed control units ([[sync/fire-alarm-systems]]); backbone pathways, conduit fill, and telecom rooms ([[sync/structured-cabling]]); cellular and public-safety radio coverage ([[sync/distributed-antenna-systems]]); security and access-control entrance intercoms; and auditorium sound reinforcement or AV presentation systems.
---
…4 unchanged lines
## It applies to schools, universities, offices, industrial facilities, warehouses, healthcare campuses, correctional facilities, and transportation terminals where clear voice communication must reach occupants across multiple zones. {note}
−## The standard addresses both system families in current use, and the early architecture decision between them governs nearly every downstream selection. {note}
+## The standard addresses three system families in current use — 70-volt constant-voltage analog distributed audio, IP-networked audio, and a hybrid of the two — and the early architecture decision between them governs nearly every downstream selection. {note}
−### The system shall be one of the following architectures: 70-volt constant-voltage analog distributed audio, IP-networked audio (VoIP/AES67/Dante), or a hybrid retaining a constant-voltage speaker backbone with an IP paging overlay.
+## Equipment furnished under this standard includes master and remote paging stations, zone selectors, power amplifiers, pre-amplifiers, digital signal processors, loudspeakers, supervision hardware, rack infrastructure, and standby power. {note}
−### Equipment furnished under this standard includes master and remote paging stations, zone selectors, power amplifiers, pre-amplifiers, digital signal processors, loudspeakers, supervision hardware, rack infrastructure, and standby power.
−
## The standard also defines the supervised interface by which a PA system yields priority to a fire alarm Emergency Communications System (ECS), but the ECS itself is specified elsewhere. {note}
…15 unchanged lines
| Standard | Title |
|----------|-------|
−| NFPA 72 (2022) | National Fire Alarm and Signaling Code (Chapter 24 Emergency Communications Systems; intelligibility and supervision) |
−| NFPA 70 (NEC, 2023) | National Electrical Code (Article 640 audio equipment; Article 725 Class 2/3 signaling circuits; Article 800 communications cable) |
−| NFPA 101 (2021) | Life Safety Code (occupancy-specific requirements that may mandate paging capability) |
+| NFPA 72 | National Fire Alarm and Signaling Code (Chapter 24 — Emergency Communications Systems; intelligibility and supervision) |
+| NFPA 70 | National Electrical Code (Article 640 — audio signal processing, amplification, and reproduction equipment; Article 725 — Class 2 and Class 3 circuits; Article 800 — communications circuits) |
+| NFPA 101 | Life Safety Code (occupancy requirements that may mandate paging capability) |
| UL 1480 | Speakers for Fire Alarm, Emergency, and Commercial and Professional Use |
−| UL 2572 | Mass Notification Systems (dual-use paging plus emergency notification) |
−| ANSI/ASA S12.60-2010 (R2020) | Acoustical Performance Criteria, Design Requirements, and Guidelines for Schools |
−| IEC 60849 (1998) | Sound Systems for Emergency Purposes |
+| UL 2572 | Mass Notification Systems |
+| ANSI/ASA S12.60 | Acoustical Performance Criteria, Design Requirements, and Guidelines for Schools |
| IEEE 446 | Recommended Practice for Emergency and Standby Power Systems for Industrial and Commercial Applications |
# System Architecture {toc}
−## The architecture decision is the single most consequential choice in a PA project, and the brief's most common pitfall is specifying a constant-voltage analog system where the program actually needs networked paging across multiple buildings. {note}
+## The architecture decision is the single most consequential choice in a PA project, and the most common design error is specifying a constant-voltage analog system where the program actually needs networked paging across multiple buildings. {note}
−## A 70-volt analog system distributes audio as a constant-voltage signal from centralized rack amplifiers through passive loudspeakers, each fitted with a step-down transformer tapped at a chosen wattage; it is simple, robust, and the default for small-to-medium single-building facilities. {note}
+## A 70-volt analog system distributes audio as a constant-voltage signal from centralized rack amplifiers through passive loudspeakers, each fitted with a step-down transformer tapped at a chosen wattage; it is simple, robust, and well suited to small-to-medium single-building facilities. {note}
## An IP-networked system carries audio as packets over the data network to PoE zone controllers and addressable endpoint speakers, scaling cleanly across a campus and integrating with SIP telephony and unified-communications platforms, at the cost of dependence on the IT network. {note}
## A hybrid system overlays an IP paging console and routing core onto an existing constant-voltage speaker backbone, which is the economical path when reusing legacy distributed-audio wiring while adding networked control. {note}
−### Select the system architecture.
+### The system architecture shall be as indicated in the datasheet.
```datasheet
…4 unchanged lines
- IP-networked audio (PoE zone controllers, addressable endpoints)
- Hybrid (constant-voltage backbone with IP paging overlay)
−default: 70-volt constant-voltage analog (centralized rack amplifiers, passive speakers)
```
−### For IP-networked or hybrid architectures, the audio transport protocol shall be coordinated with the network design so that the required VLAN, multicast, and QoS configuration is provisioned under [[sync/structured-cabling]].
+### The architecture follows from the number of buildings served, the condition of any existing speaker backbone, and whether the owner's IT organization will carry the audio network — none of which the standard can assume — so the field carries no default. {note}
+### The audio transport protocol shall be as indicated in the datasheet.
+
```datasheet
label: IP audio transport protocol
…2 unchanged lines
- AES67
- Dante
− - Proprietary IP (manufacturer-native)
+ - AVB/Milan (IEEE 802.1 AVB)
+ - Proprietary IP transport (vendor-native)
- Not applicable (analog system)
−default: Not applicable (analog system)
```
−## Where an IP system is selected, the audio network and its supervision shall not depend on routing or services that the owner's IT group can change without notice to the PA system owner. {note}
+### For IP-networked or hybrid architectures, the audio transport protocol shall be coordinated with the network design so that the required VLAN, multicast, and QoS configuration is provisioned under [[sync/structured-cabling]].
+### The transport protocol is meaningful only once the architecture is chosen, and the choice then turns on what the owner's head-end platform and network already support, so the field carries no default. {note}
+
+## Where an IP system is selected, the audio network and its supervision shall not depend on routing or services that the owner's IT group can change without notice to the PA system owner.
+
### The PA system shall remain operable for in-zone local paging during a failure of the wide-area network connection between buildings.
# Zone Configuration and Paging {toc}
−## A zone is an independently addressable group of loudspeakers, and the zone map is the contractual definition of which call stations reach which speakers; the brief flags that omitting a zone matrix causes the contractor to default to all-call only and selective paging never works. {note}
+## A zone is an independently addressable group of loudspeakers, and the zone map is the contractual definition of which call stations reach which speakers. Where no zone matrix is issued, the contractor builds an all-call-only system and selective paging never works. {note}
−### The system shall provide the number of independently switchable speaker zones scheduled for the project.
+### The system shall provide the number of independently switchable speaker zones indicated in the datasheet.
```datasheet
label: Number of independent speaker zones
type: range
−min: 1
−max: 64
−step: 1
unit: zones
−default: 8
+drawing_ref: "zone matrix and speaker-zone plan"
+options:
+ min: 1
+ max: 256
+ step: 1
+default: deferred
```
…2 unchanged lines
### The system shall support selective paging to any single zone and to engineer-defined zone groups.
−### A zone matrix identifying every call station, the zones it may address, and each zone's grouping shall be furnished, and zone-to-speaker assignment shall follow that matrix. [[drawing: zone matrix and speaker-zone plan]]
+### A zone matrix identifying every call station, the zones it may address, and each zone's grouping shall be furnished [[drawing: as indicated on the zone matrix and speaker-zone plan]].
+### Zone-to-speaker assignment shall follow the zone matrix.
+
## Priority among audio sources determines which announcement is heard when two sources contend, and a documented priority order prevents a background-music source from masking a live page. {note}
…2 unchanged lines
### A fire alarm Emergency Communications System input, where present, shall override all PA sources, as required by the Fire Alarm Interface section.
−### The default source priority, highest to lowest, shall be as configured below.
+### The source priority order, highest to lowest, shall be fire alarm ECS override, live all-call page, live zone page, scheduled announcement, and background music; where no ECS interface is furnished, the same order applies with the ECS level omitted.
−```datasheet
−label: Source priority order (highest first)
−type: select
−options:
− - ECS override / live all-call page / live zone page / scheduled announcement / background music
− - Live all-call page / live zone page / scheduled announcement / background music (no ECS)
−default: ECS override / live all-call page / live zone page / scheduled announcement / background music
−```
−
# Paging Stations and Consoles {toc}
## Master call stations, zone selectors, and remote microphones are the operator interface, and their type is selected to match the staff that will use them; a touchscreen IP console suits a campus dispatch desk, while a simple keypad microphone suits a single front office. {note}
−### A primary paging station with microphone, zone selection, and all-call capability shall be furnished at the location scheduled. [[drawing: primary paging station location]]
+### A primary paging station with microphone, zone selection, and all-call capability shall be furnished [[drawing: at the location indicated on the contract documents]].
### Each paging station shall provide a press-to-talk control and a visual ready/busy indication so the operator knows when the channel is live.
−### Select the primary paging station type.
+### The primary paging station type shall be as indicated in the datasheet.
```datasheet
…5 unchanged lines
- Touchscreen IP paging console
- Telephone-access paging interface (dial-in from any extension)
−default: Desktop keypad paging microphone (analog)
```
−### Specify the quantity of remote paging stations.
+### The station type is constrained by the architecture and by who will operate the system — a school front office, a campus dispatch desk, and a warehouse shift office give three different answers — so the field carries no default. {note}
+### The quantity of remote paging stations shall be as indicated in the datasheet.
+
```datasheet
label: Remote paging stations (quantity)
type: range
−min: 0
−max: 32
−step: 1
unit: stations
−default: 2
+drawing_ref: "zone matrix and speaker-zone plan"
+options:
+ min: 0
+ max: 64
+ step: 1
+default: deferred
```
−## A telephone-access paging interface lets staff page by dialing an extension, but the brief warns that analog dial-access interfaces may not work across SIP trunks without an analog terminal adapter; PBX compatibility must be confirmed before selection. {note}
+## A telephone-access paging interface lets staff page by dialing an extension, but analog dial-access interfaces may not work across SIP trunks without an analog terminal adapter, so PBX compatibility must be confirmed before selection. {note}
### Where a telephone-access paging interface is furnished, its compatibility with the facility telephone system, including any SIP-to-analog adaptation required, shall be confirmed in writing before rough-in.
# Amplifiers and Signal Processing {toc}
−## Amplifier sizing is driven by the summed loudspeaker tap load plus headroom; the brief's pitfall is specifying amplifiers at 100% of the calculated tap load, which leaves no margin for program peaks and shortens amplifier life. {note}
+## Amplifier sizing is driven by the summed loudspeaker tap load plus headroom; specifying amplifiers at 100% of the calculated tap load leaves no margin for program peaks and shortens amplifier life. {note}
### Each amplifier shall be sized so that the connected continuous loudspeaker tap load does not exceed 80% of the amplifier's rated continuous output.
−### Specify the per-zone amplifier continuous output rating.
+### The per-zone amplifier continuous output rating shall be as indicated in the datasheet.
```datasheet
label: Per-zone amplifier continuous output
type: range
−min: 30
−max: 500
−step: 10
unit: W
−default: 120
+options:
+ min: 30
+ max: 1200
+ step: 10
```
−### Total harmonic distortion shall not exceed the specified maximum at rated output.
+### Amplifier output is the summed tap load of the zone plus the 80% headroom allowance, which is a per-project calculation, so the field carries no default. {note}
+### Total harmonic distortion shall not exceed the maximum indicated in the datasheet at rated output.
+
```datasheet
label: Amplifier total harmonic distortion (THD) at rated output, max
type: range
−min: 0.5
−max: 5
−step: 0.5
unit: "%"
+options:
+ min: 0.5
+ max: 5
+ step: 0.5
default: 1
```
−### The amplifier frequency response shall meet the specified passband for the program content the system carries.
+### A 1% THD ceiling at rated output is met by every current commercial paging amplifier and is correct without knowing the project; a tighter limit is specified only where the system also carries program music at high level. {note}
+### The amplifier frequency response shall be as indicated in the datasheet.
+
```datasheet
label: Amplifier frequency response (±3 dB)
…5 unchanged lines
```
+### Voice-grade passband is the default because paging is the primary function and a restricted passband improves intelligibility in reverberant space; the music-capable passband is selected where background music is a real program requirement rather than an incidental feature. {note}
+
## Amplifier redundancy protects against the loss of an entire zone when a single amplifier fails, and N+1 backup with automatic failover is standard practice for systems serving large occupant loads or critical facilities. {note}
−### Select the amplifier redundancy scheme.
+### The amplifier redundancy scheme shall be as indicated in the datasheet.
```datasheet
…6 unchanged lines
```
+### One amplifier per zone is the baseline commercial arrangement and is the datasheet default; N+1 with automatic failover is an added-cost upgrade selected on occupant load and facility criticality. {note}
+
## A digital signal processor conditions the audio for each zone, and built-in equalization, delay, automatic gain control, and feedback suppression are what make a marginal room intelligible rather than merely loud. {note}
### The system shall provide per-zone digital signal processing with at least parametric equalization and level control.
−### Select the additional DSP functions required.
+### The DSP functions furnished shall be as indicated in the datasheet.
```datasheet
…15 unchanged lines
## Loudspeaker type and mounting are selected for the space: recessed ceiling speakers for finished offices and classrooms, pendant speakers for open high-ceiling areas, and horn or compression-driver speakers for warehouses, loading docks, and outdoor areas where ambient noise is high and coverage distances are long. {note}
−### Select the predominant loudspeaker type for the project.
+### The predominant loudspeaker type shall be as indicated in the datasheet.
```datasheet
…6 unchanged lines
- Horn / compression-driver speaker
- Line array (high-ceiling or reverberant spaces)
−default: Recessed ceiling speaker with back can
```
+### This standard covers finished office and classroom space, open warehouse, and outdoor areas in comparable numbers, and each takes a different predominant speaker, so the field carries no default. {note}
+
### Loudspeakers shall be listed to UL 1480 for commercial paging use.
### Loudspeakers installed in air-handling plenums shall be furnished with a listed plenum-rated back enclosure.
−## The constant-voltage distribution level and the per-speaker tap wattage together set how much acoustic power each speaker delivers; 70.7 V distribution with a 1 to 2 W tap is the 80% case for classrooms and offices, while industrial and outdoor speakers are tapped much higher. {note}
+## The constant-voltage distribution level and the per-speaker tap wattage together set how much acoustic power each speaker delivers; classroom and office speakers are commonly tapped at 1 to 2 W, while industrial and outdoor speakers are tapped much higher. {note}
−### Select the constant-voltage distribution level.
+### The constant-voltage distribution level shall be as indicated in the datasheet.
```datasheet
label: Constant-voltage distribution level
−type: radio
+type: range
+unit: V
options:
− - 70.7 V (standard commercial/institutional)
− - 25 V (small systems)
−default: 70.7 V (standard commercial/institutional)
+ min: 25
+ max: 100
+ setpoints: [25, 70.7, 100]
+default: 70.7
```
−### Specify the nominal per-speaker tap power for the predominant space type.
+### 70.7 V is the North American constant-voltage standard and is correct without knowing the project; 100 V reduces line loss on very long industrial runs, and 25 V is used on small systems where NEC Class 2 limits are easier to hold. {note}
+### The nominal per-speaker tap power for the predominant space type shall be as indicated in the datasheet.
+
```datasheet
label: Per-speaker tap power (predominant space)
−type: select
+type: range
+unit: W
options:
− - 0.25 W (quiet office, background music)
− - 0.5 W
− - 1 W
− - 2 W
− - 4 W
− - 8 W (loud industrial / outdoor)
−default: 1 W
+ min: 0.25
+ max: 30
+ setpoints: [0.25, 0.5, 1, 2, 4, 8, 15, 30]
```
−## Outdoor and wet-location speakers fail early when generic indoor housings are used; the brief calls out that horn speakers on docks, fields, and parking structures need rated enclosures and UV-stable housings. {note}
+### The low end of the tap range, 0.25 W, suits a quiet office carrying background music, while the high end, 30 W, is a high-output horn for an outdoor or industrial space. {note}
−### Loudspeakers installed outdoors or in wet, washdown, or high-humidity locations shall be rated to at least the specified enclosure standard with UV-stable housings.
+### Tap power is an output of the coverage and SPL calculation for the predominant space, and the answer spans two orders of magnitude across the occupancies this standard covers, so the field carries no default. {note}
+## Outdoor and wet-location speakers fail early when generic indoor housings are used; horn speakers on docks, playfields, and parking structures need rated enclosures and UV-stable housings. {note}
+
+### Loudspeakers installed outdoors or in wet, washdown, or high-humidity locations shall be rated to at least the enclosure standard indicated in the datasheet, with UV-stable housings.
+
```datasheet
label: Outdoor/wet-location speaker enclosure rating, minimum
type: radio
options:
- IP55
+ - IP65
- IP66
+ - NEMA 3R
- NEMA 4
- NEMA 4X
- Not applicable (no outdoor/wet locations)
−default: Not applicable (no outdoor/wet locations)
```
−## Loudspeaker placement and spacing set whether coverage is even or patchy; the brief notes that 6 m on-center is the default for ordinary 8 to 10 ft ceilings, and that HVAC diffuser locations must be reconciled with speaker locations to avoid ceiling-conflict RFIs. {note}
+### The rating depends on whether the exposure is rain, washdown, or salt air, and on whether the project has any outdoor speakers at all, so the field carries no default. {note}
−### Specify the nominal ceiling-speaker spacing on center for the predominant ceiling height.
+## Loudspeaker placement and spacing set whether coverage is even or patchy, and speaker locations must be reconciled with HVAC diffuser locations to avoid ceiling-conflict requests for information. {note}
+### The nominal ceiling-speaker spacing on center for the predominant ceiling height shall be as indicated in the datasheet.
+
```datasheet
label: Ceiling-speaker spacing (on center)
type: range
−min: 4
−max: 9
−step: 0.5
−unit: m
−default: 6
+unit: ft
+options:
+ min: 10
+ max: 40
+ step: 1
```
−### Loudspeaker locations shall be coordinated with the reflected ceiling plan and with mechanical diffuser and lighting locations before permit, and conflicts shall be resolved on a coordinated ceiling layout. [[drawing: reflected ceiling plan with speaker locations]]
+### Spacing follows from ceiling height and the loudspeaker's coverage angle — 20 ft on center is a customary starting point for an ordinary 9 to 10 ft ceiling, and open warehouse bays space far wider — so the field carries no default. {note}
+### Loudspeaker locations shall be coordinated with the reflected ceiling plan and with mechanical diffuser and lighting locations before permit [[drawing: as indicated on the coordinated reflected ceiling plan]].
+
# Cable and Power Distribution Infrastructure {toc}
−## Paging wiring is governed by two different NEC articles that apply in the same installation, and the brief stresses keeping them distinct: Article 640 covers the audio equipment power wiring and grounding, while Article 725 and Article 800 govern the low-voltage signal and communications cable. {note}
+## Paging wiring is governed by two different NEC articles that apply in the same installation, and they must be kept distinct: Article 640 covers the audio equipment power wiring and grounding, while Article 725 and Article 800 govern the low-voltage signal and communications cable. {note}
### Loudspeaker signal circuits shall be installed as NEC Class 2 circuits limited to 100 VA and 30 V where the constant-voltage level and load permit.
…3 unchanged lines
### Speaker-circuit conductors shall be sized so that loop resistance does not exceed the loudspeaker manufacturer's stated limit, typically less than 10% of the total connected load impedance.
−### Select the minimum speaker-circuit conductor size.
+### The minimum speaker-circuit conductor size shall be as indicated in the datasheet.
```datasheet
…4 unchanged lines
- 16 AWG (standard for longer runs)
- 14 AWG (long runs / high tap loads)
+ - 12 AWG (very long runs / high-output horn circuits)
default: 16 AWG (standard for longer runs)
```
+### 16 AWG is the default because it carries the great majority of commercial 70 V circuits within the loop-resistance limit; 18 AWG suits short in-room runs, and the heavier sizes are selected from the loop-resistance calculation on long or heavily tapped circuits. {note}
+
## Hum and noise complaints on constant-voltage systems are almost always a grounding or shield-termination defect rather than an equipment fault, so the rack ground and shield discipline must be specified rather than left to the installer. {note}
…4 unchanged lines
# Standby Power {toc}
−## Standby power keeps paging available through a normal-power outage, and the required backup duration depends entirely on whether the PA system also serves a life-safety function; the brief sets 15 minutes for routine paging but 24 hours where the system serves an NFPA 72 ECS function. {note}
+## Standby power keeps paging available through a normal-power outage, and the required backup duration depends entirely on whether the PA system also serves a life-safety function: 15 minutes is adequate for routine paging, while an NFPA 72 ECS function drives the requirement to 24 hours. {note}
−### The system head end, amplifiers, and call stations shall be supported by standby power for at least the scheduled backup duration.
+### The system head end, amplifiers, and call stations shall be supported by standby power for at least the backup duration indicated in the datasheet.
```datasheet
label: Standby power backup duration, minimum
−type: radio
+type: range
+unit: hours
options:
− - 15 minutes (routine paging)
− - 4 hours
− - 24 hours (PA serves NFPA 72 ECS function)
−default: 4 hours
+ min: 0.25
+ max: 24
+ setpoints: [0.25, 4, 24]
```
−### Select the standby power source.
+### The setpoints are stated in hours: 0.25 hours is the 15-minute duration adequate for routine paging, and 24 hours is the duration required where the PA system serves an NFPA 72 ECS function. {note}
+### The duration turns on whether the system carries a life-safety function, which is a project determination, so the field carries no default. {note}
+
+### The standby power source shall be as indicated in the datasheet.
+
```datasheet
label: Standby power source
…3 unchanged lines
- Shared facility UPS
- Facility standby generator with ride-through UPS
−default: Dedicated PA system UPS
```
−## The UPS supporting the amplifier room shall be sized for worst-case simultaneous all-call output, not merely idle draw, in accordance with IEEE 446.
+### The source depends on what standby infrastructure the facility already has, so the field carries no default. {note}
−## Standby power sizing for the amplifier room follows IEEE 446 guidance; the UPS must support full simultaneous all-call load, not merely idle draw. {note}
+### The UPS supporting the amplifier room shall be sized for worst-case simultaneous all-call output, not merely idle draw, in accordance with IEEE 446.
# Intelligibility and Coverage {toc}
−## Intelligibility, not loudness, is the measure of a usable paging system, and the brief insists that specifying an STI-PA target without requiring a post-installation measurement leaves the owner no remedy for a system that is loud but unintelligible. {note}
+## Intelligibility, not loudness, is the measure of a usable paging system, and specifying an STI-PA target without also requiring a post-installation measurement leaves the owner no remedy for a system that is loud but unintelligible. {note}
## Speech Transmission Index (STI-PA) quantifies how much of speech survives the room's noise and reverberation; NFPA 72 requires STI-PA at least 0.45 for an ECS, and 0.50 is a sound target for general paging. {note}
−### The system shall achieve the specified STI-PA value at no less than 90% of designated listening positions in each zone.
+### The system shall achieve the STI-PA value indicated in the datasheet at no less than 90% of designated listening positions in each zone.
```datasheet
label: Intelligibility target (STI-PA), minimum
type: range
−min: 0.40
−max: 0.70
−step: 0.05
unit: STI-PA
+options:
+ min: 0.40
+ max: 0.70
+ step: 0.05
default: 0.50
```
−### Paging audio shall produce a sound pressure level of at least the specified minimum at the listener, measured 1.5 m above finished floor.
+### 0.50 STI-PA is the general-paging target and is correct without knowing the project; it sits above the 0.45 NFPA 72 requires of an emergency communications system, giving margin for the measurement uncertainty of a field sweep. {note}
+### Paging audio shall produce a sound pressure level of at least the minimum indicated in the datasheet at the listener, measured 5 ft above finished floor.
+
```datasheet
label: Minimum SPL at listener
type: range
−min: 65
−max: 85
−step: 1
unit: dB(A)
−default: 70
+options:
+ min: 60
+ max: 95
+ step: 1
```
+### The absolute SPL floor is set from the space's measured ambient, which ranges from a 35 dB(A) classroom to a warehouse in the mid-80s, so the field carries no default. {note}
+
### Paging audio shall be at least 10 dB above the measured ambient noise level in each occupied space, and at least 15 dB above ambient where the system serves an ECS function.
…6 unchanged lines
# Supervision and Fault Monitoring {toc}
−## Supervision is what distinguishes a maintained system from one that quietly fails, and the brief treats line supervision as a core requirement: a cut or shorted speaker line, or a failed amplifier, must annunciate rather than be discovered the next time someone tries to page. {note}
+## Supervision is what distinguishes a maintained system from one that quietly fails: a cut or shorted speaker line, or a failed amplifier, must annunciate rather than be discovered the next time someone tries to page.
### Each loudspeaker circuit shall be supervised for open-circuit and short-circuit faults, and a fault shall be annunciated at the head end.
### Each amplifier shall report a fault condition, including loss of output, to the head-end annunciator.
−### Select the supervision scope.
+### The supervision scope shall be as indicated in the datasheet.
```datasheet
…14 unchanged lines
# Fire Alarm Interface {toc}
−## The interface to the fire alarm system is the most commonly under-specified item in a paging project, and the brief makes clear that most institutional occupancies require the PA system to yield priority to the fire alarm ECS; failing to specify the handshake produces a late, expensive coordination RFI with the fire alarm contractor. {note}
+## The interface to the fire alarm system is the most commonly under-specified item in a paging project. Most institutional occupancies require the PA system to yield priority to the fire alarm ECS, and failing to specify the handshake produces a late, expensive coordination request for information with the fire alarm contractor. {note}
## When the PA system is the listed NFPA 72 Chapter 24 Emergency Communications System rather than merely interfaced to one, it leaves the scope of this standard: it must then be listed to UL 2572 and specified under [[sync/mass-notification-systems]], because a generic paging spec applied to a life-safety system will fail AHJ inspection. {note}
### Where a fire alarm system is present, the PA system shall accept a supervised priority-override signal from the fire alarm control unit and shall mute or release all PA audio while that signal is active.
−### Select the fire alarm interface method.
+### The fire alarm interface method shall be as indicated in the datasheet.
```datasheet
…8 unchanged lines
```
+### A supervised dry-contact input is the default because it is the interface every listed fire alarm control unit can provide and it does not depend on a shared protocol; serial and IP integration are selected where the two head ends are from compatible platforms and richer status exchange is wanted. {note}
+
### The fire alarm override input shall be supervised so that a fault on the interface wiring is annunciated.
…4 unchanged lines
# Submittals {toc}
−## The Contractor shall submit the following action submittals for review before fabrication or ordering:
+## Action Submittals {toc}
+### The Contractor shall submit the following action submittals for review before fabrication or ordering:
+
- Product data for amplifiers, DSPs, paging stations, loudspeakers, and supervision hardware
- Shop drawings showing the system riser, zone matrix, and speaker-circuit loading calculations
…15 unchanged lines
- Shop drawings (riser, zone matrix, circuit loading)
- Coverage and STI-PA design calculations
+ - Standby power sizing calculations
- UL 1480 / UL 2572 listing documentation
```
−## The Contractor shall submit the following closeout submittals before final acceptance:
+## Closeout Submittals {toc}
+### The Contractor shall submit the following closeout submittals before final acceptance:
+
- As-built riser and zone matrix reflecting installed conditions
- Operation and maintenance manuals
…18 unchanged lines
# Quality Assurance {toc}
−## Quality assurance pins responsibility for a system whose performance is only proven after installation, so the standard requires qualified installers and, for dual-use life-safety systems, a dedicated commissioning agent as the brief warns. {note}
+## Quality assurance pins responsibility for a system whose performance is only proven after installation, so the standard requires qualified installers and, for dual-use life-safety systems, a dedicated commissioning agent. {note}
### The installing contractor shall be trained and authorized by the equipment manufacturer for the furnished system.
…11 unchanged lines
### An all-call and zone-select functional test shall be performed at the factory before shipment.
−### A full field intelligibility sweep shall be performed with an STI-PA meter at each zone, and results shall meet the specified intelligibility target.
+### A full field intelligibility sweep shall be performed with an STI-PA meter at each zone, and results shall meet the intelligibility target indicated in the datasheet.
−### Sound pressure level shall be measured at representative listening positions in each zone and shall meet the specified minimum SPL.
+### Sound pressure level shall be measured at representative listening positions in each zone and shall meet the minimum SPL indicated in the datasheet.
### Open-circuit and short-circuit faults shall be simulated on each speaker zone, and each shall annunciate at the head end.
…7 unchanged lines
### Loudspeakers shall be installed at the coordinated locations and at the spacing required to achieve the specified coverage and intelligibility.
−### All cable run in air-handling spaces shall carry the required plenum rating, and substitutions shall not be installed without engineer approval.
+### Plenum-rated cable substitutions shall not be installed without the Engineer's written approval.
−### Rack equipment shall be installed with the technical grounding and shield-termination scheme specified.
−
### Ground continuity shall be verified before energization.
…4 unchanged lines
## The warranty obligates the manufacturer and installer to stand behind the system through its early service life. {note}
−### The system shall be warranted against defects in materials and workmanship for the specified period from the date of substantial completion.
+### The system shall be warranted against defects in materials and workmanship for the period indicated in the datasheet, measured from the date of substantial completion.
```datasheet
label: Warranty period
−type: radio
+type: range
+unit: years
options:
− - 1 year
− - 2 years
− - 3 years
−default: 2 years
+ min: 1
+ max: 3
+ setpoints: [1, 2, 3]
+default: 2
```
…2 unchanged lines
## Spare parts let the owner restore service without waiting on procurement for the components most likely to fail or be damaged. {note}
−### The Contractor shall furnish the scheduled quantity of spare loudspeakers matching each installed type.
+### The Contractor shall furnish the quantity of spare loudspeakers indicated in the datasheet, matching each installed type.
```datasheet
label: Spare loudspeakers (per installed type)
type: range
−min: 0
−max: 10
−step: 1
unit: ea
+options:
+ min: 0
+ max: 10
+ step: 1
default: 2
```
+### The two-per-type spare allowance is a contractual stocking floor rather than a sized quantity, so the field carries a concrete default. {note}
+
### The Contractor shall furnish at least one spare amplifier module of each installed rating where N+1 redundancy is not provided.