Overvoltage is a condition in which voltage is higher than the level that the object is rated for. The term overvoltage is most often used to refer to voltage conditions in power lines, indicating conditions when too much voltage is traveling through a power system. It can also apply to electric-powered objects like computers to indicate that the voltage supplied to the object is greater than that for which the object is rated. For an electric company, overvoltage is sometimes used to describe a persistent level of voltage over the range designated for the power line, a problem condition that can affect electronics and energy efficiency in all buildings connected to the malfunctioning power line area.
The most damaging overvoltages are caused by an oversupply in electricity like those experienced when lighting strikes somewhere in a power grid. When overvoltages are caused by lightning strikes, the power can range in the hundreds of kilovolts (kV), high-voltage power levels that can blow fuses and damage more sensitive electrical equipment. These high voltage conditions can take out electrical equipment and cause blackouts in the surrounding areas. Overvoltage due to lightning is one of the most common natural causes of power interruptions. They can also be caused by a sudden drop in power use, like if a large, power-sucking appliance such as a central air conditioning unit is suddenly powered off or if an ear-splitting rock band suddenly shuts off its equipment all at once.
Delicate equipment that can be damaged by high voltage surges usually benefits from protection against power changes. Systems that provide overvoltage protection can also be called voltage optimization systems. The most common type of overvoltage protection is a surge protector, which generally is a strip of outlets that plugs into a wall. The surge protector has circuits that provide protection against overvoltage for the electric objects plugged into the surge protector. Advanced surge protectors condition power for delicate electronic devices, changing it so it provides optimum electric properties.
Some computer experts apply conditions of overvoltage to a computer to cause it to run faster in a process called overclocking. Providing too much voltage to a computer can cause irreparable damage to hardware in the computer if the overclocking is not done correctly and with attention and care. The most common cause of damage to a computer when overclocking is overheating the computer processor. Running a computer faster than recommended produces more heat, so overclockers must often use an advanced cooling system to remove the extra heat produced when a computer user jacks up the voltage.