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In industrial and commercial systems, PLTC— Power-Limited Tray Cable —plays a vital role in low-voltage control and instrumentation applications. Engineered for signal integrity, environmental resistance, and simplified installation, PLTC balances stringent UL and NEC compliance with operational flexibility.
Origins & Applicability
PLTC was developed to meet the demand for reliable, tray-rated cabling in power-limited control systems. Recognized under UL 13, it is rated for 300 volts and permitted for use in Class 2 and Class 3 remote-control and signaling circuits under NEC Article 725. Unlike general-purpose tray cables, PLTC was specifically designed for applications where signal transmission, installation efficiency, and mechanical resilience are all equally important.
Over time, PLTC evolved to include enhanced variants, such as PLTC-ER (Exposed Run), which provide additional mechanical strength for unsupported runs between cable trays and devices. These are permitted under NEC 725.154 when installed per support and protection requirements. PLTC-ER has no formal maximum length limit but must be secured at intervals no greater than 6 feet to comply with NEC guidelines.
Where PLTC Is Used
PLTC cable is relied upon in a wide range of installations requiring consistent, noise-resistant signal transmission and secure routing:
- Instrumentation and control systems
- Alarm, security, and intercom circuits
- Building automation and energy management systems
- PLC wiring in industrial panels
- Mass transit and substation control environments
A major advantage of PLTC is its ability to be installed directly in cable trays without conduit. PLTC-ER extends that flexibility, allowing short, unsupported runs when properly secured. With available ratings for outdoor use, direct burial, and hazardous locations (e.g., Class I/II Div 2), PLTC offers a durable and compliant solution across diverse electrical environments.
Construction & Features
- Conductors: Most PLTC cables use stranded bare copper conductors ranging from 22 AWG to 12 AWG. The stranding enhances flexibility, making it easier to route through trays, control panels, and tight bends without compromising performance.
- Insulation: Conductors are insulated with robust thermoplastic materials such as PVC or EPR, typically rated to 105°C. These materials resist oil, moisture, and chemicals while maintaining reliable dielectric strength under harsh conditions.
- Shielding: Shielded versions may use individual foil shields for pairs or triads, plus an overall foil or foil-braid combination. This layered structure reduces EMI and crosstalk in environments with VFDs, motors, and analog signal lines.
- Jacket: The outer jacket is typically sunlight-resistant PVC that resists oils, water, and abrasions. All PLTC cables must pass the UL 1685 and IEEE 1202 vertical tray flame tests. Many also meet CSA FT4 flame ratings and are approved for direct burial and wet location use.
- Ease of Installation: Many PLTC cables include rip cords beneath the jacket to aid in stripping. Their small diameter and lightweight construction allow easier routing in cable trays and industrial enclosures.
PLTC vs. Other Tray Cables
| Feature | PLTC | TC (Tray Cable) | ITC (Instrumentation Tray Cable) |
|---|---|---|---|
| Voltage Rating | 300 V (Class 2/3) | 600 V | 300 V (instrumentation & signal) |
| Conductor Range | AWG 22–12 stranded copper | Heavier gauge for power | Similar to PLTC, often twisted |
| Shielding | Optional – overall/pair/triad | Often unshielded or limited | Typically shielded for EMI protection |
| Environmental Resistance | Oil/UV/water/flame resistant | Similar; varies by jacket | Comparable; often burial-rated |
| Exposed Run (ER) Capability | PLTC-ER: yes, supported if secured every 6 ft | TC-ER: yes, typically ≤ 6 ft | ITC-ER: yes, max 50 ft drop |
| NEC Article | 725 | 336 | 727 |
| Typical Applications | Low-voltage control, alarms, automation | Power/control circuits, motors | Instrumentation, sensors, DCS wiring |
| Separation Requirement | Must separate from 600 V circuits | Same requirement applies | Must remain isolated |
Why These Differences Matter
PLTC is optimized for low-voltage signal control and excels where compact routing, shielding, and installation flexibility are critical. Compared to TC, which handles up to 600 V and serves power/control systems, PLTC is tailored for Class 2/3 control circuits and excels in environments that demand shielding and reduced cable diameter. ITC cables offer similar voltage ratings and EMI performance, but are typically used in precise instrumentation contexts.
PLTC-ER and ITC-ER are both tested for crush and impact resistance, enabling conduit-free exposed runs between tray and equipment under certain NEC conditions. PLTC-ER must be supported at intervals not exceeding 6 feet, but it does not have the 50-foot length restriction that applies to ITC-ER.
Key Takeaways
PLTC cable is a purpose-built solution for 300-volt power-limited control and instrumentation circuits. It offers a dependable mix of durability, code compliance, shielding options, and installation flexibility. With options for direct burial, exposed-run routing, and rugged construction, it continues to serve as a trusted choice for engineers, contractors, and OEMs across a wide range of industrial environments.
