What is a power surge? A power surge occurs when the line voltage goes higher than nominal and stays there longer than ten milliseconds. This can damage any of your appliances and all of your electronics. Surges occur when devices with motors such as refrigerators and hair dryers shut off.
Roughly 40% of the problem is generated outside the home or office, but 60% of all electrical surges are generated within the home. Some way surges are caused include: air conditioners, copiers, computers and even lights turning on and off.