830.90 Primary Electrical Protection
Exception: Primary electrical protection shall not be required on the network-powered broadband communications conductors where electrical protection is provided on the derived circuit(s)(output side of the NIU) in accordance with 830.90(B)(3).
Informational Note No. 1: On network-powered broadband communications conductors not exposed to lightning or accidental contact with power conductors, providing primary electrical protection in accordance with this article helps protect against other hazards, such as ground potential rise caused by power fault currents, and above-normal voltages induced by fault currents on power circuits in proximity to the networkpowered broadband communications conductors.
Informational Note No. 2: Network-powered broadband communications circuits are considered to have a lightning exposure unless one or more of the following conditions exist:
- Circuits in large metropolitan areas where buildings are close together and sufficiently high to intercept lightning.
- Areas having an average of five or fewer thunderstorm days each year and earth resistivity of less than 100 ohmmeters. Such areas are found along the Pacific coast.
Informational Note No. 3: For information on lightning protection systems, see NFPA 780-2017, Standard for the Installation of Lightning Protection Systems.
- A listed primary protector shall be applied on each network-powered broadband communications cable external to and on the network side of the network interface unit.
- The primary protector function shall be an integral part of and contained in the network interface unit. The network interface unit shall be listed as being suitable for application with network-powered broadband communications systems and shall have an external marking indicating that it contains primary electrical protection.
- The primary protector(s) shall be provided on the derived circuit(s) (output side of the NIU), and the combination of the NIU and the protector(s) shall be listed as being suitable for application with networkpowered broadband communications systems.
For purposes of this section, a network interface unit and any externally provided primary protectors located at mobile home service equipment located in sight from and not more than 9.0 m (30 ft) from the exterior wall of the mobile home it serves, or at a mobile home disconnecting means grounded in accordance with 250.32 and located in sight from and not more than 9.0 m (30 ft) from the exterior wall of the mobile home it serves, shall be considered to meet the requirements of this section.
Informational Note: Selecting a network interface unit and primary protector location to achieve the shortest practicable primary protector bonding conductor or grounding electrode conductor helps limit potential differences between communications circuits and other metallic systems.