A GUIDE TO UL LISTINGS
Underwriters Laboratory (UL) is a third-party safety consulting and certification company that sets standards for an array of commercial, industrial, and consumer products. UL evaluates more than 70 different wire and cable product categories for safety, performance, quality, environmental impact, and regulatory compliance.
Wire and cable products with a UL listing have been tested and approved by UL and meet the requirements of the National Electrical Code (NEC). A different file number is assigned for each approved construction and includes product specifications such as insulation material and voltage rating.
UL 1277: POWER AND CONTROL TRAY CABLE
UL 1277, the standard for electrical power and control tray cable, was recently updated, allowing manufacturers with UL approved tray cable to market their product as 600V/1kV rated. To be dual rated, products must use a recognized 1kV rated conductor and pass a higher voltage AC Hipot test on the completed cable. This test requires each insulated conductor in finished cable to withstand a specified voltage range for one minute without breakdown. If a product passes the AC Hipot test, it is suitable for 1kV use.
BENEFITS OF DUAL RATED TRAY CABLE
Dual rated tray cable is a more robust product. It is a cost-effective alternative for applications that require a lower voltage cable but are at risk for potential voltage spikes. For example, 1kV rated tray cable can withstand greater electrical adversity; the impact of a disruptive event on the cable is smaller, and the recovery time is faster than in a less resilient system.
UL dual rated tray cable also offers flexibility in newer constructions. With new 575V and 690V motors appearing, standard XHHW-2 tray cable can now be used because of its increased 1kV rating.
Additionally, dual rated tray cable has a smaller outside diameter than traditional 1kV tray cables, making it preferable in space-constrained installations.