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.