In the U.S—with the exception of utility, telecommunications and rail industries—all AC power connected surge protective devices (SPDs) must be installed in accordance with National Electrical Code (NEC).
The 2017 revision of the NEC includes three articles that address SPD application and expand its use outside for emergency power systems:
- Article 620.51(E), Surge Protection for Elevators, Dumbwaiters, Escalators, Moving Walks, Platform Lifts and Stairway Chairlifts
- Article 645.18, Surge Protection for Critical Operations Data Systems
- Article 670.6, Surge Protection for Industrial Machinery
The NEC requires that a SPD be “listed” or recognized for such purpose and approved by a Nationally Recognized Testing Laboratory (NRTL). One example of a NRTL listing service is Underwriters Laboratories Inc. (UL).
The broadening application of the NEC furthers the responsibility for NRTLs, like UL, to prioritize safety for facilities, electrical professionals and patrons. Read on to learn about the main UL standard that assesses SPD products for safety and provides basic ratings for determining applications.