ESD (electrostatic discharge) test meters are used to measure the level of electrostatic discharge on a person, surface, or piece of equipment. This is to prevent damage to other equipment, such as flip-flop integrated circuits or other devices with integrated circuits, that might be caused by sparks from excess ESD. These sparks may also be a fire hazard.
ESD test meters measure electrostatic discharge by monitoring the surface resistance level to determine whether it is within an acceptable range for safety. A light or series of lights is often used to indicate this.
ESD test meters can vary quite widely in their specific function, depending on what they are measuring. They can be battery or mains operated, and may be worn on the wrist or mounted onto a surface. They can therefore be of different sizes and may utilise different equipment to measure the level of electrostatic discharge, such as a foot plate or an outlet analyser.