Basics of Tray Cable
Tray Cable is designed for installation in cable trays, as specified in the National Electric Code, for industrial control systems, factories, wind turbines, and more. Tray-rated cables came about when failures on power and communications cables were becoming quite common. This occurred mainly when smaller cables were placed under larger cables and the environments were too rugged for some of the cables and didn’t meet testing standards. Tray-rated cable can be used for signal, control, and power. When researching tray cable, there are a few different types to choose from. These types include, Tray Cable (TC), Power Limited Tray Cable (PLTC), Instrumentation Tray Cable (ITC), Exposed Run (ER), and Wind Turbine Tray Cable (WTTC).
TC and PLTC cables are very similar. The main difference between TC and PLTC is that TC is rated at 600V and PLTC is rated at 300V. Similar to PLTC, ITC cables, which can act as an alternative to PLTC, have the same construction and materials as PLTC, thus allowing a lot of PLTC cables to have the ITC designation as well. Although ITC has a 300V rating, it is suggested to use up to 150V with a 5 Amp maximum current. According to NEC Article 727, type ITC cable can only be installed in industrial applications where the conditions of maintenance and supervision ensure that only qualified persons will service the installation. For your information, typical materials used in tray cable are THHN, THWN, XLPO, and EPR as insulation and typical jacket materials include PVC, CPE, CSPE.
An extension to the tray rated cable, is an exposed run (ER) rating which can be adapted for the TC, PLTC, and ITC cables. Exposed run cables need to be rugged enough to use as exposed or open wiring without laying in cable trays. In order to be an exposed run cable, extra crush and impact testing is required as these cables are not going to be fully placed in a cable tray. An advantage of choosing exposed run cable is that it is less expensive than your standard tray cable and the exposed cable can be used up to 50 feet past the cable tray without having additional armor or be held within a tray.
Hopefully these basics of tray cable provide you with the groundwork for understanding when to use tray cables and the importance of the rating.