It is important to understand the basic aspects of a cable’s construction and performance. Knowing the fundamental characteristics of a cable will help you understand your product options and allow you to make better wire and cable choices. It will also be easier to communicate what you want when placing an order. We’ll show you a six-point method for identifying the most common types of Tray Cables and Power Limited Tray Cables.

Six attributes commonly used to define a cable:

1. Wire Size
2. Conductor
3. Insulation
4. Shield
5. Jacket
6. Voltage Rating

We will use these criteria to describe tray cables and power limited tray cables (PLTC). Step by step, we will identify the parts of the cable as well as the most common options available for each type.

Tray Cables

1. Wire Size– How big is the conductor? This is commonly measured in AWG (American Wire Gauge).
2. Conductor– How many conductors or pairs (sets of 2 conductors twisted together)? What is the color code? Does it have a ground wire?
3. Insulation– Does it use THHN/THWN, XHHW, EPR, or XLPO? If it has THHN/THWN insulation, it is Type VNTC Tray Cable. THHN stands for “thermoplastic high heat-resistant nylon-coated.” In this case, the THHN insulation consists of extruded PVC with a nylon coating. If the cable features XHHW insulation, it is Type XLP Tray Cable. XHHW is short for “XLPE (cross-linked polyethylene) high heat-resistant water-resistant.”
4. Shield– Standard shielding is Aluminum Mylar foil with a drain wire. However, shielding may not be required.
5. Jacket– Is it made with PVC, CPE, or Hypalon*?
6. Voltage Rating– Standard TC cables are 600 volts.

PLTC

1. Wire Size– What is the conductor’s AWG size?
2. Conductor– How many pairs or triads does the cable have? Pairs are two conductors twisted together. Triads are composed of three conductors.
3. Insulation– Does it have PVC or EPR insulation?
4. Shield– Is it built with an overall shield (OAS) and a drain wire? These are OAS cables, but they can be referred to more specifically as POS cables: paired with overall shield, or TOS: triad cables with an overall shield. Or does it have the other popular shielding option of individually shielded pairs/triads with drain wires, along with an overall shield and another drain wire? These are called SPOS: shielded pairs overall shield, or STOS: shielded triads overall shield.
5. Jacket– What material is used? Is it PVC, CPE, or Hypalon*?
6. Voltage Rating – PLTC cables are rated to 300 volts. Instrumentation Tray Cable is rated to 600V.

Now that we’ve used our six-point method to identify the most common types of tray cable and power limited tray cable, you should be more familiar with which characteristics to look for, and which construction options are common for each type. Next time you discuss tray cables and power limited tray cables, you should have all of the basics down!

*Hypalon is a Dupont Trademark, chemical compound CSPE