This standard applies to low voltage gas discharge tube (GDT ) surge-protective components for application on systems with voltages less than or equal to 1000 V rms or 1500 V dc. These protective components are designed to limit voltage surges on balanced or unbalanced communication circuits and on power circuits operating from dc to 420 Hz. This standard contains a series of standard test criteria for determining the electrical characteristics and ratings of gas discharge tube surge-protective components. The tests in this standard are intended as design tests as defined in the IEEE Standards Dictionary Online and provide a means of comparison among various gas discharge tube surge-protective components. Gas discharge tubes are used to provide over-voltage protection in electrical circuits. When the breakdown (sparkover) voltage of the gas discharge tube is exceeded, the normal high-impedance state of the tube changes to a low-impedance state to allow the gas discharge tube to conduct the surge discharge current. After the tube conducts the surge discharge current, it interrupts the flow of power follow current and returns to its high impedance state. This standard's test criteria and definitions provide a common engineering language that is beneficial to the user and manufacturer of gas discharge tube surge-protective components. Due to the voltage and energy levels employed in the majority of tests contained herein, all measurements should be considered hazardous and appropriate caution should be taken in their performance.