Article 840 Premises-Powered Broadband Communications Systems
Informational Note: A typical basic system configuration consists of an optical fiber, twisted pair, or coaxial cable to the premises supplying a broadband signal to a network terminal that converts the broadband signal into component electrical signals, such as traditional telephone, video, high-speed Internet, and interactive services. Powering for the network terminal and network devices is typically accomplished through a premises power supply that might be built into the network terminal or provided as a separate unit. In order to provide communications in the event of a power interruption, a battery backup unit or an uninterruptible power supply (UPS) is typically part of the powering system.
Broadband. Wide bandwidth data transmission that transports multiple signals, protocols, and traffic types over various media types.
Network Terminal. A device that converts network-provided signals (optical, electrical, or wireless) into component signals, including voice, audio, video, data, wireless, optical, and interactive services, and is considered a network device on the premises that is connected to a communications service provider and is powered at the premises.
Premises Communications Circuit. The circuit that extends voice, audio, video, data, interactive services, telegraph (except radio), and outside wiring for fire alarm and burglar alarm from the service provider's network terminal to the customer's communications equipment up to and including terminal equipment, such as a telephone, a fax machine, or an answering machine.
Premises Community Antenna Television (CATV) Circuit. The circuit that extends community antenna television (CATV) systems for audio, video, data, and interactive services from the service provider's network terminal to the appropriate customer equipment.
- Installations of communications circuits — Part IV of Article 805
- Installations of premises (within buildings) community antenna television and radio distribution circuits — Part V of Article 820
- Installations of optical fiber cables — Part V of Article 770
- Installations of Class 2 and Class 3 circuits — Part III of Article 725
- Installations of power-limited fire alarm circuits — Part III of Article 760
Exception No. 2: Separation shall not be required where the electric light or power branch-circuit or feeder conductors, non-power-limited fire alarm circuit conductors, or Class 1 circuit conductors are installed in a raceway or in metal-sheathed, metal-clad, or Type UF or Type USE cables.
Informational Note: See NFPA 780-2017, Standard for the Installation of Lightning Protection Systems, for the theory of the term rolling sphere.
- Any of the methods described in 820.100 or 800.106
- A fixed connection to an equipment grounding conductor as described in 250.118
- Connection to the network terminal grounding terminal provided that the terminal is connected to ground by one of the methods described in 820.100 or 800.106, or to an equipment grounding conductor through a listed grounding device that will retain the ground connection if the network terminal is unplugged
Informational Note: Where required to be grounded, a listed device that extends the equipment grounding conductor from the receptacle to the network terminal equipment grounding terminal is permitted. Sizing of the extended equipment grounding conductor is covered in Table 250.122.
Informational Note: See NFPA 780-2017, Standard for the Installation of Lightning Protection Systems, for the application of the term rolling sphere.
Exception: Installing communications cables in compliance with 725.144 shall not be required for listed 4-pair communications cables where the rated current of the power source does not exceed 0.3 amperes in any conductor 24 AWG or larger.
Informational Note: A typical communications cable for this application is a 4-pair cable sometimes referred to as Category 5e (or higher) LAN cable or balanced twisted pair cable. These types of cables are often used to provide Ethernet- and Power over Ethernet (PoE)-type services. A large number of such powering cables bundled together can cause overheating of the wiring if not controlled as described in Table 725.144.
Informational Note No. 1: One way to determine applicable requirements is to refer to ANSI/UL 60950-1-2014, Standard for Safety of Information Technology Equipment; ANSI/UL 498A-2015, Current Taps and Adapters; ANSI/UL 467-2013, Grounding and Bonding Equipment; or ANSI/UL 62368-1-2014, Audio/Video, Information and Communication Technology Equipment - Part 1: Safety Requirements.
- A power source shall be listed as specified in 725.121(A)(1), (A)(2), (A)(3), or (A)(4). The power sources shall not have the output connections paralleled or otherwise interconnected unless listed for such interconnection.
- A power source shall be listed as communications equipment for limited-power circuits.
Informational Note: One way to determine applicable requirements is to refer to ANSI/UL 60950-1-2014, Standard for Safety of Information Technology Equipment-Safety - Part 1; or ANSI/UL 62368-1-2014, Audio/Video, Information and Communication Technology Equipment - Part 1: Safety Requirements. Typically, such circuits are used to interconnect equipment for the purpose of exchanging information (data).