A surge protector works by channeling the extra voltage into the outlet's grounding wire, preventing it from flowing through the electronic devices while at the same time allowing the normal voltage to continue along its path. Electrical surges can damage computer equipment by burning its wires or gradually over time wearing down the device’s internal components and even wipe out any saved data. Surge protectors can also protect telephone and cable lines as these also carry electric current.

It is a common misunderstanding that surge protectors will protect systems from lightning, the most familiar source of power surges. Even the most effective surge protectors can not protect equipment from the sudden increase in electrical pressure of millions of volts that lightning can supply. The best way to prevent damage during from lightning storm is to unplug devices that could be irreparably damaged. Surge protectors more commonly protect equipment from lower-voltage surges that occur frequently in modern electrical wiring. For example, devices such as refrigerators and air conditioners require large amounts of energy to switch motors and compressors on and off, creating surges in power that disrupt the steady flow of voltage. Faulty wiring, downed power lines and faulty equipment at the power source (utility company) can all cause power surges as well.

Surge protectors are also commonly called power strips, surge suppressors and transient suppressors.

Comparison of power protection methods
Compares the level of protection offered by different types of devices, such as UPS's, line conditioners, and surge suppressors. This page is from "The PC Guide".

External power problems
Describes common electrical problems, such as line noise, surges, and brownouts. This page is part of "The PC Guide".

Protection against power problems
Describes devices, such as surge suppressors and line conditioners, that can help with electrical problems. This page is part of "The PC Guide".