Switching spark gaps are a voltage-controlled piece of equipment used in the surge protection of electrical devices. They are used to switch circuits where you need the switch to happen fast and at a high energy, but without losing too much of that energy. They break down in the event of a voltage spike, shunting the excess voltage safely to the ground. They can operate at a wide range of temperatures.
Switching spark gaps are often used in heating and gas appliances, both in buildings and in automotive vehicles. They can also be found in high voltage switches, in power plants and electrical substations, and large power transformers.
Switching spark gaps have differing capacities for operation. This means that their voltage tolerance, peak current, maximum switching frequency and breakdown voltage can all vary, sometimes significantly. They can also differ by size, in the length and diameter of their tube.