Surges are very high voltage peaks that can cause significant damage to electrical and electronic equipment and can also degrade conductors and render an installation unusable. There are two types of overvoltages, permanent and transient. Permanent overvoltages are caused by a possible decompensation of the supply phases due to a possible break in the neutral. Transient overvoltages can be caused by a lightning strike on the power supply line or on a telecommunications installation.