Power-Limited Tray Cable Vs Instrumentation Tray Cable (PLTC Vs ITC)

A Comprehensive Technical Guide to Power-Limited Tray Cable and Instrumentation Tray Cable.

1. Introduction

In North American industrial, commercial, and building automation systems, PLTC (Power-Limited Tray Cable) and ITC (Instrumentation Tray Cable) are two of the most commonly specified control and signal cable types.

Because both cable types:

Are approved for cable tray installation

Are widely used for control, signal, and instrumentation circuits

Share similar physical constructions (multi-conductor, twisted pairs, shielding)

they are frequently confused or incorrectly interchanged.

However, from a code compliance, electrical classification, and application standpoint, PLTC and ITC are fundamentally different cable types. This article provides a detailed, engineering-level explanation of their definitions, standards, certifications, applications, similarities, and differences.

2. What Is PLTC (Power-Limited Tray Cable)?

2.1 Definition

PLTC stands for Power-Limited Tray Cable.

PLTC is a cable type specifically designed for power-limited circuits, primarily Class 2 and Class 3 circuits, and approved for installation in cable trays.

The defining characteristic of PLTC is power limitation, not simply tray suitability.

2.2 Governing Standards and Codes

PLTC cables are recognized by UL specifically for power-limited control and signal circuits, where available fault energy is restricted by design.

2.3 Typical Construction

PLTC cables commonly feature:

Conductors

Bare copper or tinned copper

Common sizes: 18–24 AWG

Insulation

PVC, XLPE, or polyethylene

Configuration

Multi-conductor

Twisted pairs or triads

Shielding (optional)

Aluminum/Mylar foil

Copper braid

Drain wire

Outer Jacket

Flame-retardant PVC

Tray-rated flame performance

2.4 Certifications and Marking

PLTC cable jackets typically include:

"PLTC" or "PLTC-ER"

UL Listing mark

UL file number

Voltage and temperature ratings

Manufacturer identification

2.5 Typical Applications of PLTC

PLTC is widely used in low-power control and signal systems, such as:

PLC I/O signal wiring

Building automation systems (BAS)

Fire alarm control circuits (where permitted)

Security and access control systems

Low-power industrial control circuits

Sensors and actuators operating under Class 2 or Class 3 limitations

Key takeaway:
PLTC is intended for power-limited systems, not for higher-energy industrial instrumentation or power distribution.

3. What Is ITC (Instrumentation Tray Cable)?

3.1 Definition

ITC stands for Instrumentation Tray Cable.

ITC is designed for industrial instrumentation and process control circuits, and is approved for installation in cable trays, but is not power-limited.

3.2 Governing Standards and Codes

Unlike PLTC, ITC cables may carry higher energy levels, as long as they remain within instrumentation and control limits defined by NEC.

3.3 Typical Construction

ITC cables are generally engineered for industrial environments:

Conductors

Bare or tinned copper

Common sizes: 18–22 AWG

Insulation

XLPE or polyethylene (chemical and thermal resistance)

Pairing

Twisted pairs or triads (instrumentation standard)

Shielding

Individual pair shielding

Overall foil or braid shielding

Outer Jacket

Industrial-grade PVC, CPE, or equivalent

3.4 Certifications and Marking

Typical ITC cable jacket markings include:

"ITC" or "ITC-ER"

UL Listing mark

Voltage and temperature ratings

Manufacturer identification

3.5 Typical Applications of ITC

ITC is commonly used in industrial and process control environments, including:

Distributed Control Systems (DCS)

Process instrumentation (temperature, pressure, flow)

4–20 mA analog loops

Digital and analog control signals

Power plants, refineries, chemical and manufacturing facilities

Key takeaway:
ITC is an industrial instrumentation cable, not restricted to power-limited circuits.

4. Key Differences Between PLTC and ITC

4.1 Core Technical Differences

4.2 Compliance Logic (Critical in Engineering)

PLTC compliance logic:

"This is a power-limited circuit; therefore, PLTC is required."

ITC compliance logic:

"This is an instrumentation circuit; ITC is permitted."

⚠ Important:

ITC does not automatically substitute for PLTC.

PLTC does not automatically substitute for ITC.

Substitution is only acceptable if explicitly approved by the project specification or the AHJ (Authority Having Jurisdiction).

5. Similarities Between PLTC and ITC

Despite their differences, PLTC and ITC share many characteristics:

Approved for cable tray installation

UL Listed

Designed for control and signal transmission

Available with shielding and drain wires

Similar physical appearance

Available in ER (Exposed Run) versions

6. PLTC-ER vs. ITC-ER (Exposed Run)

The ER (Exposed Run) designation means:

The cable may be installed outside the cable tray

No metallic conduit is required for short exposed runs

Typically limited to equipment connection distances

Important note:
ER classification affects installation method only and does not change:

Power limitation

Circuit classification

NEC article applicability

7. Practical Selection Guidelines

Choose PLTC when:

The circuit is Class 2 or Class 3

The system is power-limited by design

The application involves building automation or low-power control

Choose ITC when:

The system is an industrial instrumentation circuit

Higher energy control loops are involved

Process control reliability and EMI resistance are critical

Avoid substitution when:

Specifications explicitly call for PLTC or ITC

The project is subject to strict inspection

Industrial or hazardous locations are involved

8. Summary

PLTC and ITC cables may look similar, but they serve different regulatory and functional purposes.

PLTC is a power-limited control cable.
ITC is an industrial instrumentation cable.
Similar construction does not imply interchangeable use.

Correct cable selection ensures code compliance, system safety, and long-term reliability.