A power surge is a transient voltage spike in a power or data line. The most familiar cause is lightning strikes, but it is actually just one of several common reasons.
More frequent causes include the switching on and off of high-powered machinery such as elevator motors or air conditioners. The resulting changes in magnetic or electrical fields around these high-power lines can lead to voltage transients in surrounding cabling.
Surges can also occur as a result of faulty equipment or downed power lines. In today’s complex power distribution system, this kind of event should be considered inevitable.
Electronic equipment is constantly shrinking in scale, and modern, delicate components are increasingly sensitive to excessive variations in current and voltage. If a sufficiently powerful transient enters the equipment, it may become irrevocably damaged and even catch on fire.