NEC Rules for Supporting Coaxial Cable (CATV) in Installations

Image ALT Text: A properly installed coaxial cable is secured with a coaxial cable support strap to a wooden joist in a new construction environment.

Properly supporting coaxial cable is not just about neatness; it’s a critical safety and performance requirement governed by the National Electrical Code (NEC). For any journeyman electrician or master electrician working with CATV or other low voltage systems, understanding these rules is essential for a compliant and reliable installation. According to NEC Article 820, coaxial cable installations must be performed in a professional and skillful manner, ensuring the cable is protected from physical damage and does not create a hazard. Key principles involve using independent supports, maintaining separation from power conductors, and respecting the cable’s minimum bend radius. Adhering to the nec code book ensures that the coaxial cable system performs optimally without interference and, most importantly, protects people and property from potential electrical and fire hazards. This involves specific rules for securing cables, grounding, and dealing with legacy wiring.

The Foundation: NEC Article 820 and Workmanlike Installation

The primary reference for CATV and radio distribution systems in the United States is Article 820 of the National Electrical Code. This article provides the comprehensive rules for the safe installation of coaxial cable. However, before diving into the specifics of Article 820, it’s crucial to understand the foundational principle found in NEC 110.12: Mechanical Execution of Work. This section mandates that all electrical equipment, including low-voltage wiring, be installed in a “professional and skillful manner.” While this may seem subjective, it sets the expectation that installations must be orderly, secure, and free from defects that could compromise safety or performance. For both a master electrician overseeing a project and a journeyman electrician performing the hands-on work, a workmanlike installation is the starting point for every job.

Core Principles of Supporting Coaxial Cable

Article 820, in conjunction with other NEC sections it references, establishes clear guidelines for securing and supporting coaxial cable. These rules are designed to protect the cable’s integrity, ensure signal quality, and prevent hazardous interactions with other building systems. For more detail on the full scope of CATV installations, see our lesson on how CATV installations are handled in the 2023 NEC.

Independent Support and Proper Fastening

One of the most violated rules in low-voltage wiring involves how cables are supported. NEC 820.133(B) is clear: coaxial cables cannot be strapped, taped, or attached by any means to the exterior of any conduit or raceway as a means of support. Tying cables to electrical metallic tubing (EMT) or other raceways is a code violation. Instead, coaxial cables require independent support wires or must be attached directly to structural components like framing members or joists. When securing these cables, you must use fittings designed for the purpose, such as dedicated coaxial cable support straps or listed tie wrap cable ties that do not damage the cable. Using staples that are too tight or zip ties that deform the cable’s shape can alter its electrical properties and degrade the signal. For further guidance on this topic, explore our article on how electrical cables should be tied.

Managing Coaxial Cable Bend Radius

NEC 820.24 states that cables shall be installed in a way that does not damage the cable, which includes preventing excessive bending. Bending a coaxial cable too sharply can change its characteristic impedance, leading to signal reflections and poor performance. The NEC does not specify a universal minimum coaxial cable bend radius; instead, it defers to the manufacturer’s instructions, a critical part of any electrician training. As a general industry rule of thumb, the bend radius should be at least 10 times the cable’s outer diameter, though some modern cables may tolerate a tighter radius of 6 times the diameter. When in doubt, always consult the specifications for the specific type of electrical cable you are installing.

Supporting Vertical Cable Runs

When installing cable between floors, supporting vertical cable runs is critical. The cable’s own weight can cause it to stretch over time, leading to conductor damage and signal degradation. In vertical runs, cables must be supported to prevent damage from their own weight; for risers in shafts, NEC 820.53(E) requires support at the top of the run and at intervals not exceeding 30 m (98 ft). This is also where cable ratings become important. A riser-rated coaxial cable (Type CATVR or CMR) is designed with fire-resistant characteristics for use in vertical shafts that pass between floors.

Critical Safety: Separation, Grounding, and Protection

Beyond simple support, the NEC places significant emphasis on protecting coaxial cables from external electrical and physical threats.

Separation from Power Conductors

To prevent induced currents and potential shock hazards, NEC 820.133 dictates the required separation from power conductors. Coaxial cables must be kept at least 2 inches away from conductors of electric light, power, and Class 1 circuits. This rule has exceptions, such as when the power or coax cables are installed in a raceway or when they are permanently separated by a continuous and firmly fixed barrier like a wooden stud. Understanding this electrical code for low-voltage wiring is non-negotiable for safety.

CATV Grounding Requirements

Proper grounding is arguably the most important safety aspect of a CATV installation. NEC 820.93 and 820.100 detail the CATV grounding requirements. The outer conductive shield of the coaxial cable must be grounded as close as practicable to the point of entrance into the building. This is typically done with a listed grounding block bonded to the building’s main grounding electrode system. The bonding conductor should be at least 14 AWG copper, be as short and straight as possible, and not exceed 20 feet in one- and two-family dwellings where practicable. This connection equalizes the potential between the CATV system and the building’s power, preventing dangerous voltages from entering the home during lightning strikes or utility line faults.

Protection from Physical Damage

Where coaxial cables are exposed and subject to physical damage, they must be protected. This requirement, found in NEC 820.24, applies to areas like unfinished basements, garages, or any location where the cable could be hit, crushed, or abraded. Protection can be provided by running the cable inside a raceway, such as EMT or PVC conduit, or by routing it through bored holes in framing members at least 1.25 inches from the nearest edge.

Step-by-Step Guide for a Compliant CATV Installation

1. Plan the Route: Before pulling any cable, map out a path that respects separation from power conductors, avoids sharp bends, and provides adequate access to structural members for support.
2. Select the Right Cable: Choose the correct cable type for the application. Use plenum-rated coaxial cable (Type CATVP or CMP) for spaces used for environmental air (plenums) and riser-rated coaxial cable (Type CATVR or CMR) for vertical runs between floors.
3. Install Support Structures: If not using building framing, install any necessary independent support wires or mounting hardware. Remember, never use other conduits or pipes as a support structure.
4. Pull and Secure the Cable: Pull the cable along the planned route, avoiding excessive tension. Fasten it using listed coaxial cable support straps or other approved fittings, ensuring they are not over-tightened. For a deeper dive into this, see our electrical cable management guide.
5. Ground and Bond the System: At the building’s point of entry, install a grounding block. Connect it to the intersystem bonding termination or the main grounding electrode system using a correctly sized bonding conductor as specified in NEC 820.100.
6. Perform a Final Check: Inspect the entire run to ensure a workmanlike installation. Verify all separation, support, and bend radius requirements are met and that the cable is properly protected from physical damage.

Advanced Topics and Best Practices

A professional installation goes beyond the minimum code requirements. Mastering best practices demonstrates a higher level of expertise and ensures a more robust and future-proof system.

Bundling Coaxial Cables and Cable Management

When bundling coaxial cables, use hook-and-loop (Velcro) straps or loosely applied tie wrap cable ties to avoid deforming the cables. In commercial settings, a cable tray is often the preferred method for supporting large bundles of low-voltage wiring, providing continuous support and easy access for future work.

The Importance of Removing Abandoned Cable

NEC 820.25 mandates that accessible portions of abandoned CATV cables must be removed. An “abandoned” cable is one that is not terminated at equipment and not identified for future use with a tag. This rule was introduced to reduce the fuel load in buildings during a fire and to prevent confusion when troubleshooting or installing new systems. The choice of plenum-rated cable ties can also impact fire safety, a topic covered in our lesson on how NEC rules affect plenum cable tie selection.

Mastering these low-voltage installations requires dedicated knowledge. Expand your skills into low voltage and data cabling. See our specialized courses.

Key Takeaways for Coaxial Cable Support

• Always reference NEC Article 820 from the current nec code book for CATV installations.
• Coaxial cable must be supported independently and never by being attached to raceways or plumbing.
• Maintain a minimum 2-inch separation from power conductors unless a specific code exception is met.
• Fulfilling CATV grounding requirements at the point of entry is a critical life-safety step.
• Always complete the job with a neat and workmanlike installation, ensuring cables are protected and secure.

Primary Sources

• NFPA 70, National Electrical Code (2023 Edition), published by the National Fire Protection Association.

Frequently Asked Questions (FAQ)

What is the proper support spacing for supporting coaxial cable?

While NEC Article 820 does not give a prescriptive spacing interval like it does for other cable types, the rule of a “workmanlike installation” (NEC 110.12) and preventing damage (NEC 820.24) is the guide. Industry best practice, derived from other data cabling standards, is typically to support horizontal runs every 4 to 5 feet.

Can I use regular zip ties for tying cables like coax?

You should only use tie wrap cable ties that are listed and designed for low-voltage data cables. Regular zip ties can be easily over-tightened, compressing the dielectric, changing the cable’s impedance, and harming signal performance. Using specialized coaxial cable support straps or hook-and-loop ties is a safer alternative.

What does the nec code book say about bundling coaxial cables with power cables?

The NEC explicitly prohibits this. According to NEC 820.133, coaxial cables cannot be placed in the same raceway, compartment, or enclosure with electric light and power conductors unless they are separated by a permanent barrier or another exception applies. The standard rule is to maintain at least a 2-inch separation.

Is abandoned cable removal really mandatory for low voltage wiring?

Yes. NEC 820.25 requires that the accessible portions of abandoned CATV cables be removed unless they are clearly tagged for future use. This applies to cables above drop ceilings and in other accessible areas. The primary reasons are to reduce fire load and prevent confusion during maintenance and upgrades.