Article 640 Audio Signal Processing, Amplification, and Reproduction Equipment
Informational Note: Examples of permanently installed distributed audio system locations include, but are not limited to, restaurant, hotel, business office, commercial and retail sales environments, churches, and schools. Both portable and permanently installed equipment locations include, but are not limited to, residences, auditoriums, theaters, stadiums, and movie and television studios. Temporary installations include, but are not limited to, auditoriums, theaters, stadiums (which use both temporary and permanently installed systems), and outdoor events such as fairs, festivals, circuses, public events, and concerts.
Audio Amplifier or Pre-Amplifier. Electronic equipment that increases the current or voltage, or both, of an audio signal intended for use by another piece of audio equipment. Amplifier is the term used within this article to denote an audio amplifier.
Audio Signal Processing Equipment. Electrically operated equipment that produces, processes, or both, electronic signals that, when appropriately amplified and reproduced by a loudspeaker, produce an acoustic signal within the range of normal human hearing (typically 20—20 kHz). Within this article, the terms equipment and audio equipment are assumed to be equivalent to audio signal processing equipment.
Informational Note: This equipment includes, but is not limited to, loudspeakers; headphones; pre-amplifiers; microphones and their power supplies; mixers; MIDI (musical instrument digital interface) equipment or other digital control systems; equalizers, compressors, and other audio signal processing equipment; and audio media recording and playback equipment, including turntables, tape decks and disk players (audio and multimedia), synthesizers, tone generators, and electronic organs. Electronic organs and synthesizers may have integral or separate amplification and loudspeakers. With the exception of amplifier outputs, virtually all such equipment is used to process signals (utilizing analog or digital techniques) that have nonhazardous levels of voltage or current.
Maximum Output Power. The maximum power delivered by an amplifier into its rated load as determined under specified test conditions.
Rated Output Power. The amplifier manufacturer's stated or marked output power capability into its rated load.
Technical Power System. An electrical distribution system where the equipment grounding conductor is isolated from the premises grounded conductor and the premises equipment grounding conductor except at a single grounded termination point within a branch-circuit panelboard, at the originating (main breaker) branch-circuit panelboard, or at the premises grounding electrode.
Informational Note: NFPA 90A-2018, Standard for the Installation of Air-Conditioning and Ventilating Systems, 220.127.116.11.6.5, permits loudspeakers, loudspeaker assemblies, and their accessories listed in accordance with UL 2043-2013, Fire Test for Heat and Visible Smoke Release for Discrete Products and Their Accessories Installed in Air-Handling Spaces, to be installed in other spaces used for environmental air (ceiling cavity plenums).
Informational Note: For installation requirements for such combination systems, refer to NFPA 72-2016, National Fire Alarm and Signaling Code, and NFPA 101-2018, Life Safety Code.
- Date cable was identified for future use
- Date of intended use
- Information related to the intended future use of cable
Informational Note: Refer to NFPA 72-2019, National Fire Alarm and Signaling Code, where equipment is used for a fire alarm system.
Audio amplifier output circuits wired using Class 1 wiring methods shall be considered equivalent to Class 1 circuits and shall be installed in accordance with 725.46, where applicable.
Audio amplifier output circuits wired using Class 2 or Class 3 wiring methods shall be considered equivalent to Class 2 or Class 3 circuits, respectively. They shall use conductors insulated at not less than the requirements of 725.179 and shall be installed in accordance with 725.133 and 725.154.
Informational Note No. 1: ANSI/UL 1711-2016, Amplifiers for Fire Protective Signaling Systems, contains requirements for the listing of amplifiers used for fire alarm systems in compliance with NFPA 72-2019, National Fire Alarm and Signaling Code.
Informational Note No. 2: Examples of requirements for listing amplifiers used in residential, commercial, and professional use are found in ANSI/UL 813-1996, Commercial Audio Equipment, ANSI/UL 1419-2016, Professional Video and Audio Equipment, ANSI/UL 1492-1996 revised 2013, Audio-Video Products and Accessories; ANSI/UL 6500-1999 revised 2013, Audio/Video and Musical Instrument Apparatus for Household, Commercial, and Similar Use, and UL 62368-1-2014, Audio/Video, Information and Communication Technology Equipment — Part 1: Safety Requirements.
Exception: This section does not include audio systems intended for use on boats, yachts, or other forms of land or water transportation used near bodies of water, whether or not supplied by branch-circuit power.