Overvoltages due to lightning strikes or electrostatic discharges are potentially damaging to electrical equipment. All kinds of devices within the equipment may be damaged by this means. Overvoltage surge arresters are used to avoid this. They limit hazardous overvoltages in electrical cables and equipment. For effective protection, several types of overvoltage surge arresters must be combined, depending on the situation. A distinction is made between the following variants: Spark gaps, gas discharge tubes, varistors and suppressor diodes.