The Guide to Surge Protectors
By: Jonathan Z. Kremer
You're trying to get some sleep. There is a jolting thunderstorm outside. The windows are rattling and there are bright flashes of light coming in from the sky. You finally turn over and go back to sleep. The next morning you get up and notice that the refrigerator is not working, your computer is not booting, and your microwave is dead.
You're sitting home trying to get some last minute work done, when the electricity starts to act up. The lights go dim and then bright. After another minute or two everything goes black. You wait awhile, but then decide to go over to the neighbor to see if they are having similar problems. As you start to leave, the power goes back on. You say "great, back to work." But as you head back to the living room you realize that your stereo isn't working. Then you notice that the computer monitor is flickering and your computer just makes funny noises when you try to put it on.
Both above scenarios are examples of the type of damage electrical surges can cause. A voltage surge is a temporary increase in "normal" electrical line voltage, which is usually not more than 500-600 volts. A surge or spike (same as a surge but for a very short period of time - although it can measure in the thousands of volts) can be caused by downed power lines, a blown transformer, lightning, electric power grid switching, etc. Surges don't only travel through the electrical cables, but through TV antennas, telephone cables, or any other object that acts as a conductor. Appliances and electronics aren't the only thing that surges can destroy. They can ruin electrical outlets, light switches, light bulbs, air conditioner components, garage door openers...and more.
Other types of power interference:
Although surges are probably the most serious form of power interference, they are not the only form.
A Voltage Dip (sag or brownout): A voltage dip happens when high-power electrical devices (such as elevators, air conditioners, dishwashers, and refrigerators) come on, and create sudden, brief demands for power which upsets the steady voltage flow in the electrical system.
Flickering or dimming lights are a common symptoms of a voltage dip.
EMI: There is also electromagnetic interference (EMI). This happens when the electromagnetic field of one device disrupts, impedes or degrades the electromagnetic field of another device by coming into proximity with it. This can scramble computer memory and disturb TV and radio reception. Fortunately, it doesn't cause physical damage to appliances and electronic devices.