You're right to be concerned. Running non-tray-rated cable in a cable tray is generally a code violation. Here's a breakdown of the issues and why your assessment is likely correct: NEC (National Electrical Code) Requirements



Article 392 of the NEC covers cable trays. It specifically outlines the types of cables that are permitted to be installed in cable trays. NEC 392.3(B) requires cables to be identified for cable tray use. This means they must be marked as either ITC (Instrumentation Tray Cable), PLTC (Power-Limited Tray Cable), TC (Tray Cable), or another appropriate listing for cable tray applications. Without a tray rating, the cable is not designed for the physical and environmental stresses within a cable tray. This includes abrasion, crushing, bending, and potential exposure to chemicals or other substances that could degrade the cable insulation. Why Tray Rating Matters



Mechanical Protection

Cable trays are designed to provide support and routing for cables, but they can also create potential hazards if the cable is not robust enough. The tray rating indicates the cable has been tested and approved to withstand the conditions within the tray.

Fire Resistance

Tray-rated cables often have enhanced fire-resistant properties. In the event of a fire, they are designed to limit the spread of flames along the cable tray.

Code Compliance

As mentioned, using non-tray-rated cable in a cable tray is a violation of the NEC and other electrical codes.

Typical Thermocouple Extension Cable

Standard thermocouple extension cable is often designed for general instrumentation and control applications. It may not be specifically designed or tested to meet the requirements for cable tray use. While it might look similar to tray-rated cable, the insulation materials and construction can be different.

The Inspector's Perspective

Electrical inspectors are responsible for ensuring that electrical installations comply with the NEC and local codes. They will likely reject any installation that uses non-tray-rated cable in a cable tray. They're looking for the proper markings on the cable jacket to confirm it's suitable for the application.

Alternatives


Use Tray-Rated Thermocouple Extension Cable

This is the preferred solution. Look for TC-ER, ITC, or PLTC-rated thermocouple extension cable. These cables are designed for use in cable trays and will meet code requirements. Check the manufacturer's datasheet to confirm it's suitable for the temperature and environmental conditions of your application.2.

Run Conduit for the Entire Run

If tray-rated cable is not readily available or cost-prohibitive, running conduit for the entire 25-foot run is a code-compliant alternative. Ensure the conduit is properly sized and supported. Use appropriate fittings and sealants to protect the wiring.3.

Consider Liquid Tight Flexible Metal Conduit (LFMC) from the Cable Tray to the termination points. This may allow the use of the non tray rated cable from the tray, but only from the tray to the termination point. The conduit would need to be properly secured. Your Recommendation

You are correct in your assessment. I would advise the field to

avoid using the non-tray-rated cable in the cable tray. Tell them to use one of the following: Preferred

Replace the existing cable with TC-ER rated thermocouple extension cable.

Alternate

Install conduit (or liquid tight flexible metal conduit to their termination points) for the entire run.

Important Considerations



Refer to the Cable Manufacturer's Data Sheet

Always consult the cable manufacturer's data sheet for specific information about the cable's ratings and approved applications.

Local Codes

Check with the local electrical authority (AHJ) for any specific requirements or interpretations of the NEC that may apply in your area.*

Environmental Conditions: Ensure that the cable (regardless of whether it's tray-rated or in conduit) is suitable for the temperature, moisture, chemical exposure, and other environmental conditions of the installation.By following these guidelines, you can ensure a safe, code-compliant, and reliable thermocouple wiring installation. Flag for review