This standard applies to surge-protective devices (SPDs) intended to be installed on the load side of the service equipment connected to 50 Hz or 60 Hz alternating current (ac) power circuits rated at 1000 V (root mean squared [rms]) or less. Performance characteristics and standard methods for testing and rating are established for these devices, which may be composed of any combination of components. The tests in this standard are aimed at providing comparisons among the variety of surge-protective devices available. The purpose of this standard is to provide users, independent laboratories, and manufacturers with test methods and test specifications applicable to low-voltage surge-protective devices used on the load side of the service equipment, intended for limiting transient overvoltages that can appear on ac power circuits of 1000 V (rms) or less. Revision Standard - Superseded. Surge-protective devices (SPDs) intended to be installed on the load side of the service equipment connected to 50 Hz or 60 Hz AC power circuits rated at 1000 V (root mean squared [rms]) or less are the focus of this standard. Performance characteristics and standard methods for testing and rating are established for these devices, which may be composed of any combination of components. The tests in this standard are aimed at providing comparisons among the variety of SPDs available.