By Eileen Harvey
Key Takeaways
- Tray cables are multi-conductor cables built for cable trays and raceways, with insulation and jackets that resist mechanical stress, oil, sunlight, moisture and chemicals.
- The main types are TC (general purpose), TC-ER (exposed run), ITC (instrumentation) and PLTC (power-limited), each suited to different circuits and environments.
- In the U.S., tray cables are governed by NEC Article 336 (TC), Article 727 (ITC) and Article 725 (PLTC), and built to UL 1277; in Canada, CSA C22.2 No. 230 applies.
- Tray cables are used across industrial automation, data centers, commercial buildings, renewable energy, oil and gas, water treatment and marine applications.
- Correct installation, including the right rating, conductor size, support and separation of circuits, is essential for safety and reliability.
When it comes to powering, automating and protecting facilities—from factories and petrochemical plants to data centers and high-rises—the right cable makes all the difference. Among the various cable types, tray cables are a preferred solution for robust, adaptable, code-compliant wiring. Whether you’re an engineer, contractor, facilities manager or simply curious, this ultimate guide provides an in-depth understanding of tray cables, covering their types, standards, applications, installation practices and essential safety and compliance insights.
What Are Tray Cables?
Tray cables (TC) are multi-conductor cables designed and rated for installation in cable trays and raceways or supported by messenger wires. Unlike standard electrical cables, tray cables feature enhanced insulation and jacketing to withstand mechanical stress and exposure to oil, sunlight, moisture and a variety of chemicals. They are manufactured to carry power, control signals or data in commercial, industrial and utility environments. Insulation choice matters too; compare the options in PVC vs. XLPE insulation for tray cables.
Tray cables simplify complex wiring needs by neatly and safely delivering power or signals over long distances, even in harsh or hazardous areas. Their design focuses on flexibility, durability and the ability to meet stringent industry standards for both safety and performance.
Types of Tray Cables
One size does not fit all in modern installations. There are several categories of tray cable, each tailored for specific environments and code requirements.
1. TC – General Purpose Tray Cable
TC (tray cable, per NEC Article 336, UL 1277) is a versatile cable suitable for use in cable trays, raceways and even direct burial (if specifically rated). TC can be used for power, lighting and control circuits in industrial and commercial locations. They’re available in many conductor counts, gauges and insulation compounds.
2. TC-ER – Tray Cable with Exposed Run Rating
TC-ER (tray cable, exposed run) is a step up in construction. It’s designed for use not only in trays but also in exposed runs of up to 6 feet (1.8 meters) between the tray and equipment, replacing the need for conduit in specified circumstances (in industrial establishments where only qualified persons service the installation). This cable includes impact- and crush-resistant jacketing, meeting additional crush and impact standards verified by Underwriters Laboratories (UL). A further variant, TC-ER-JP, is also permitted in some residential applications; learn more in our article on using tray cables in residential wiring.
3. ITC – Instrumentation Tray Cable
ITC (instrumentation tray cable, NEC Article 727) is intended for low energy (not exceeding 150 volts and 5 amps) control, signal and communication circuits. Often used for PLCs, DCS systems, transmitters and other instrumentation, ITC is characterized by smaller conductors and enhanced noise resistance. Some versions (ITC-ER) also permit short exposed runs.
4. PLTC – Power Limited Tray Cable
PLTC (power limited tray cable, NEC Article 725) is used in Class 2 and Class 3 power-limited circuits for alarm systems, intercoms, security and building automation. PLTC offers similar protections as TC but is suitable for jobs with lower voltage and limited power. For more on how voltage ratings differ between types, see what is the maximum voltage rating of tray cables?
5. MC Cable and Others
While metal-clad (MC), armored, and AWM (appliance wiring material) cables are not tray cables per se, they are worth mentioning. Many share similar environments and requirements for mechanical resilience and safe routing in harsh industrial spaces. Whichever type you choose, it must meet the right standards.
Key Standards: NEC, UL, and CSA
Code compliance isn’t just bureaucracy—it’s a matter of life safety and long-term reliability. The world of tray cables is defined by three main standards:
1. NEC (National Electrical Code)
NEC Article 336 sets out the rules for the installation and use of tray cables in the U.S., including permitted locations, physical support, ampacity, exposure and more.
NEC Article 725 covers PLTC, while Article 727 covers ITC, specifying where and how they can be installed, their limitations, and their conditions for exposed runs.
2. UL (Underwriters Laboratories)
UL 1277 quantifies tray cable construction, testing for insulation thickness, flame resistance, crush resistance and exposure to chemicals and sunlight. Cables should bear markings such as “UL TC-ER” or “UL ITC-ER” for easy compliance checks.
3. CSA (Canadian Standards Association)
Tray cables used in Canada must comply with CSA C22.2 No. 230 and other pertinent standards. Insist on CSA listings or markings for any North American cross-border projects. Compliance ensures not just legality, but uninterrupted insurance coverage, safety for personnel and minimized risk of costly shutdowns or equipment failures. With the standards covered, let’s look at where tray cables are used.
Applications in Industrial and Commercial Settings
Where will you find tray cables hard at work? Virtually everywhere mission-critical power or signals are needed. Common applications include:
Industrial Automation
Tray cables power motors, pumps, relays, PLCs, and sensors along production lines, chemical processes, pulp and paper mills and more. With their resilience against oil, solvents, vibration and abrasion, they’re ideal for harsh plant floor environments. See why they matter for machinery in why tray cables are essential for powering and controlling heavy equipment.
Data Centers and Telecommunications
Used in cable trays above or below “server farms,” tray cables link power distribution units (PDUs), backup generators and environmental controls.
Commercial Buildings
HVAC, lighting control, building automation, access control, fire alarms, intercoms and security cameras all run on reliable tray cables for uninterrupted power and data.
Utilities and Renewable Energy
Tray cable is found in solar farms, wind turbines and utility-scale battery storage—often with sunlight and direct-burial ratings for exterior use.
Oil and Gas, Water Treatment
With specialized chemical and hazardous area ratings, tray cables survive corrosive atmospheres and classified areas in refineries, water plants and outdoor electrical sub-panels.
Marine and Shipbuilding
Tray cables with enhanced moisture and salt resistance power vessels, rigs and maritime facilities. Whatever the application, a reliable installation depends on getting the basics right.
Tray Cable Installation Best Practices
- Match the rating to the location: use TC-ER where cables leave the tray, direct-burial-rated cable underground and sunlight-resistant cable outdoors.
- Size conductors correctly: account for ampacity, voltage drop and derating. Our tray cable size chart is a good starting point.
- Support and secure cables: follow NEC Article 392 for cable tray installation and fill, and respect the manufacturer’s minimum bend radius.
- Separate circuits: keep power, control and instrumentation cables apart as required by code to reduce interference and maintain safety.
- Add protection where needed: use conduit where cables face physical damage or where code requires it. Learn more in do tray cables need to be in conduit?
- Bond and ground metal cable trays in accordance with the NEC.
Still have questions? Here are the ones we hear most often.
FAQs About Tray Cables
What is the difference between TC and TC-ER tray cable?
TC cable is designed to run in cable trays, raceways and other approved supports. TC-ER cable passes additional crush and impact tests, which allows it to leave the tray for exposed runs of up to 6 feet to connected equipment without conduit, under the conditions set by the NEC.
What is the difference between ITC and PLTC?
ITC (instrumentation tray cable) is used for instrumentation and control circuits limited to 150 volts and 5 amps, under NEC Article 727. PLTC (power-limited tray cable) is used for Class 2 and Class 3 power-limited circuits such as alarms and security systems, under NEC Article 725.
Can tray cable be buried directly in the ground?
Only if it is specifically marked for direct burial. Tray cable without a direct-burial rating must be installed in conduit or duct when run underground.
Can tray cable be used in homes?
Only Type TC-ER-JP tray cable is permitted, in one- and two-family dwellings under NEC 336.10(9), and only under specific conditions. Standard TC and TC-ER cables are not permitted for dwelling wiring.
Conclusion
Tray cables are an essential foundation for safe, efficient and scalable electrical and signal transmission in today’s complex world of automation, industrial IoT and smart buildings. Selecting the right cable type, following NEC/UL/CSA standards, and implementing best installation and maintenance practices keeps your facilities—and your people—operational, safe and prepared for whatever the future brings.
When planning your next project or facility upgrade, always consult with a qualified cabling provider or standards expert. You can explore TKD Cables for high-performance, NEC-compliant cable solutions designed for demanding industrial, commercial and utility environments. The investment in correctly specified, compliant tray cable systems pays for itself in reliability, up-time and peace of mind.
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