Homes and offices are literally filled with devices that can be damaged in the event of a power surge. Any electrical device that contains a microprocessor is vulnerable to power surges. Some of the most sensitive microprocessors can be damaged with only a fluctuation of around 10 volts. Surge protectors act a buffer when an electrical surge occurs and redirects the voltage so that it can be dissipated without causing damage.
Thousands of home consumer items contain microprocessors including TVs, computers, phones, microwaves, and stereos. Even items that would seemingly operate without the tiny components, such as refrigerators, stoves, dishwashers, and washing machines, contain microprocessors that could be damaged in the event of a power surge. Extreme power surges, like lightening strikes, can cause damage to electrical circuits in appliances throughout the house while lower level surges cause internal circuitry to degrade quicker. Low level surges often occur throughout the day, maybe even 100s of times, and won't leave evidence that is visibly obvious on the outside.
Power surges
When the flow of electricity is stopped or interrupted, then resumed again, a power surge is said to occur. Power surges can also happen when voltage flows back into the electrical system. Surges can be as small as 10 volts, when a blender is turned on, to 1000s volts if a lightening strike occurs.
Power surges that happen internally
Internal power surges, the type that can be protected against with individual surge protectors, are far more common than most people realize. These power surges happen throughout the day when appliances start or stop. When appliances start or stop electricity from other appliances is redirected. Air conditioners, refrigerators, and computers are common appliances that cause this problem and should always be protected with surge protectors. However, smaller appliances like hair dryers, blenders, toasters, and power tools can cause internal power surges and should be protected as well.
Power surges that happen externally
External power surges are often caused by downed trees or limbs touching power lines, lighting strikes, or when a transformer blows at a utility station. Surge protectors that provide protection for the entire house can be used to prevent damage from external power surges. These surge protectors are often installed on the meter or electrical panel and will need to be installed by a licensed electrician. External power surges also occur when power comes back on after it has been off and can enter through cable and telephone lines as well.
More information on surge protectors