Let's break down whether Garflex (likely meaning Flexible Metallic Conduit - FMC) tubing carrying Ethernet cabling is permitted in a cable tray, and how it relates to NEC 300.8.

Understanding the Components



Garflex (FMC)

Flexible Metal Conduit, often used for short runs and bends where rigid conduit is impractical. It offers mechanical protection but typically isn't watertight unless specifically rated.

Ethernet Cabling

Typically CAT5e, CAT6, CAT6A, etc., used for data communication. These are low-voltage cables.

Cable Tray

A support system for cables, designed to route and manage various types of wiring.

NEC 300.8 (Raceways as Means of Support)

This section of the National Electrical Code (NEC) addresses using raceways as a means of support for other raceways, cables, or equipment. It's primarily concerned with ensuring that raceways and their supports are not overloaded or subjected to forces they weren't designed for.

The Core Question: Is FMC Carrying Ethernet Cables Allowed in Cable Tray?The answer is generally YES, with some crucial caveats related to support, securing, and overall installation practices.

Here's a detailed breakdown:1. Permitted Use of FMC

FMC is permitted to enclose Ethernet cables, based on the listing and intended use of the FMC and the Ethernet cables' insulation rating. Ethernet cables are low voltage and generally do not create heat.2.

Cable Tray as Support

Cable trays are specifically designed to support cables and raceways. Installing the FMC on the cable tray is a common and acceptable practice.3.

NEC 300.8 (Raceways as Means of Support) Considerations



Mechanical Integrity

The key is that the installation must maintain the mechanical integrity of both the FMC and the cable tray. This means: The FMC must be adequately supported and secured to the cable tray. You can't just lay it in there loosely. Typically, appropriate clamps or straps listed for use with FMC and suitable for attachment to the cable tray are required. The weight of the FMC and its contents (the Ethernet cables) must not overload the cable tray's designed capacity. Cable trays have load ratings, and you need to ensure you're within those limits. The installation must not put undue stress on the FMC, its connectors, or the cable tray itself. Avoid sharp bends or unsupported spans that could cause the FMC to sag or break. FMC connectors must be properly tightened and suitable for the application (i.e., listed for use with FMC).4.

Other NEC Considerations



NEC 725 (Class 2 and Class 3 Remote-Control, Signaling, and Power-Limited Circuits)

Ethernet cabling often falls under these classifications. Pay attention to the requirements for separation from power conductors, proper labeling, and other installation rules outlined in Article 725. While separation isn't usually a major concern within a cable tray dedicated to low-voltage cables, it's good practice to keep power and low-voltage cables physically separated where possible.

NEC 800 (Communications Circuits)

This article also applies to communications wiring.

Manufacturer's Instructions

Always follow the manufacturer's instructions for the cable tray, the FMC, and any associated fittings and connectors. This is crucial for ensuring a safe and compliant installation.

Common Problems & Things to Watch Out For



Lack of Proper Support

The most common issue is simply laying the FMC in the cable tray without properly securing it. This can lead to sagging, stress on the connectors, and potential damage to the cabling.

Overloading the Cable Tray

Ensure the cable tray is not overloaded. Consult the manufacturer's specifications for load capacity.

Incompatible Fittings

Using the wrong type of connectors can compromise the mechanical integrity of the installation and create a potential fire hazard.

Sharp Bends in FMC

Avoid exceeding the minimum bending radius for the FMC. Too sharp a bend can damage the conduit and the cables within.

Mixing Power and Data Cables

While not strictly prohibited in all cases for open cable trays, it is best practice to maintain physical separation between power and data cables where practical. Use dividers in the cable tray if necessary.

In Conclusion

Yes, FMC carrying Ethernet cabling can* be installed in a cable tray, but only if done properly. The key is to ensure the installation adheres to NEC 300.8 by providing adequate support, not overloading the cable tray, using appropriate fittings, and following all manufacturer's instructions. Proper securing and support of the FMC to the cable tray is essential.

Recommendation:

Have a qualified electrician or low-voltage installer review the existing installation to ensure it meets all applicable NEC requirements and local codes. They can identify any deficiencies and recommend corrective actions to ensure a safe and compliant installation. This is especially important if the field installation was done without proper planning or knowledge of the NEC. Provide the documentation (load ratings, installation instructions) for the FMC, connectors, and the cable tray to the electrician. Flag for review