Electrical power is a driving force behind today's economy. As such, electricity is used to power machinery of all types, motors, electronic equipment, computers, appliances, and it provides lights and heat for millions of homes and offices. Unfortunately, electricity is influenced by factors both external and internal that are often beyond our control. These events that have a negative effect on power quality can often damage sensitive electronic circuits and computer equipment. These events can take many different forms but very often present themselves as a transient, spike, voltage surge, voltage sag, brownout, or blackout. It is important to understand that many of these same events that cause power problems also have a negative impact on phone lines, cable TV, and private communications or data lines that also may connect to your computer or electronic equipment.