A power surge is a significant, temporary increase in voltage that surpasses the designated level of electrical flow in a circuit. These surges can inflict serious damage on electronic devices and appliances, potentially degrading their performance, reducing their lifespan, or outright destroying them. The intensity of power surges can vary, with some being so minor they are almost imperceptible, while others are powerful enough to cause immediate and catastrophic damage.

Power surges can come from a variety of external or internal sources. Externally, lightning strikes are among the most dramatic and powerful causes of surges, capable of sending an overwhelming amount of electrical energy through power lines and into homes. Other external sources include utility grid disruptions, such as outages and grid switching operations, and downed power lines. Internally, power surges often result from the operation of high-powered appliances, such as air conditioning units and refrigerators, which can draw a significant amount of power suddenly, disrupting the steady flow of electricity and generating surges within the home.