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NEC Section 800.48, new in the 2023 edition, addresses the installation of unlisted outside plant communications and CATV-type coaxial cables that enter a building. These types of cables are typically not listed for fire resistance or flame propagation characteristics required for cables used within building interiors. As such, their installation is restricted to protect life safety and reduce fire load risk.
Permissible Installation Conditions:
Unlisted outside plant communications cables and unlisted CATV-type coaxial cables may be installed inside a building under the following three strict conditions:
Definition of Point of Entrance:
The “point of entrance” is typically where the cable physically penetrates the external wall, roof, or floor slab. However, NEC 800.48 allows this point to be extended if the entrance cable is continuously enclosed in RMC or IMC from the point of penetration to the point where the cable emerges and is accessible.
This means that the effective “entrance” can be moved deeper into the building provided that the cable is fully protected within metallic raceways (RMC or IMC) until it emerges.
Supporting Informational Notes:
Cables used inside buildings are typically required to be listed for flame spread and smoke production per NEC Chapter 8. Unlisted outside plant cables have not been tested to these standards, making them a potential fire hazard if installed extensively indoors. The 15-meter rule and enclosure requirements provide a controlled way to transition from outside plant infrastructure to code-compliant interior cabling systems without creating unnecessary risk.
This section reinforces the NEC’s broader emphasis on life safety and property protection by limiting the exposure of unlisted cables to indoor environments. Any installation beyond what is described in 800.48 would require listed cabling or complete metal conduit protection.
Permissible Installation Conditions:
Unlisted outside plant communications cables and unlisted CATV-type coaxial cables may be installed inside a building under the following three strict conditions:
- Length Limitation:
The cable may only extend 15 meters (50 feet) inside the building, measured from its point of entrance. - Entry Point Requirement:
The cable must enter the building from the outside, not from another interior location. - Termination Requirement:
- For communications cables, the cable must be terminated in an enclosure or on a listed primary protector.
- For CATV-type coaxial cables, they must be terminated at a grounding block.
Definition of Point of Entrance:
The “point of entrance” is typically where the cable physically penetrates the external wall, roof, or floor slab. However, NEC 800.48 allows this point to be extended if the entrance cable is continuously enclosed in RMC or IMC from the point of penetration to the point where the cable emerges and is accessible.
This means that the effective “entrance” can be moved deeper into the building provided that the cable is fully protected within metallic raceways (RMC or IMC) until it emerges.
Supporting Informational Notes:
- Note 1: Clarifies that both metallic and plastic enclosures, such as splice cases or terminal boxes, are commonly used to terminate or splice communications cables.
- Note 2: Warns that while the rule allows up to 15 meters of cable inside the building, Section 805.90(B) requires primary protectors to be located as close as practicable to the point of entrance. This means in some cases, the 50-foot allowance may be reduced if conditions allow the protector to be located closer.
Cables used inside buildings are typically required to be listed for flame spread and smoke production per NEC Chapter 8. Unlisted outside plant cables have not been tested to these standards, making them a potential fire hazard if installed extensively indoors. The 15-meter rule and enclosure requirements provide a controlled way to transition from outside plant infrastructure to code-compliant interior cabling systems without creating unnecessary risk.
This section reinforces the NEC’s broader emphasis on life safety and property protection by limiting the exposure of unlisted cables to indoor environments. Any installation beyond what is described in 800.48 would require listed cabling or complete metal conduit protection.