Most homes and businesses use modern electronic equipment such as computers, entertainment centers, microwaves, and cordless phones. All of these electronics are susceptible to power surges or spikes. This means that in less than a second, the normal 120/240 volts of electricity feeding your electronics could jump up to 400 volts or higher.
These surges can be caused by traffic accidents, broken tree limbs, down power lines, high winds, and many other disturbances. Your own house may cause surges from routine operations such as running a dishwasher or dryer.
Surge protectors are designed to trap the voltage that exceeds the limits. When the spikes occur for a sufficient duration, the trapping device is activated.
Most surge protectors will continue to function as a power strip even though the surge trap mechanism was destroyed by a power surge. This is dangerous because if another surge occurs, the equipment plugged in could be damaged. Also, if sufficient voltage passes through the surge protector due to another power surge, a short may be formed allowing overheating to occur and possibly a fire to ignite.