The risk of overvoltage surges is increasing as distribution systems and loads become ever more complex. Motors, capacitors and equipment for converting current, such as motor controls with variable speed, can cause electric arcs. Lightning strikes in power lines outdoors can cause extremely dangerous surges with high energy. When you take measurements on electrical systems, these surges constitute an “invisible” and mostly unavoidable risk. They occur regularly in low voltage circuits and can peak at values of thousands of volts. In order to help protect yourself against surges, safety must be built in to the test equipment.