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Photo by Joshua McHugh

It's a typical weekend evening. Your son is blow-drying his hair before a date and your spouse is making popcorn in the microwave. You decide to check your e-mail, but just as you get online, the monitor flickers, the cursor freezes and your hard drive crashes. You know you're facing a pricey repair, but what you might not realize is that you're the hapless victim of a voltage surge.

Surges are an especially nasty example of the power interference that occurs in homes every day. They can damage or destroy everything from PCs to VCRs, even if you use a fuse-protected multioutlet strip. That's because outlet strips like these-despite what you may have been told-are powerless against voltage surges.

"And without surge protection," warns Jim Korona, principal engineer for power quality at Detroit Edison, "your electronic equipment is toast."


There are three main forms of power interference. A voltage dip happens when motors in high-draw devices such as dishwashers and refrigerators come on and greatly reduce the suck energy available for other devices. Flickering lights are a common sign. Electromagnetic interference is generated by everyday electrical activity. Although it doesn't cause physical damage, it can scramble computer memory and hurt TV and radio reception.

As annoying as these two are, they're much less harmful than a surge, the mother of all power interference. This momentary rise in voltage can start inside or outside a home, and can fry sensitive electronic equipment like computers.

Most surges occur when devices with motors — hair dryers, refrigerators, water pumps — shut off. Suddenly the energy these devices were consuming is diverted elsewhere in the form of excess voltage. Surges also happen when the electric company switches power from one geographic area of the grid to another as supply and demand in the region changes.

The best, least expensive way to deal with most sources of power interference is to plug sensitive, expensive electronic equipment into a surge suppressor. Most suppressors resemble power strips with their outlets set up in a line or in a

2-by-2 or 2-by-3 arrangement; they cost from $20 up to $150. Established manufacturers include Panamax, Tripp Lite, and American Power Conversion.

Suppressors work by absorbing some of the electrical surge and diverting the rest to ground. The top ones use sophisticated components that allow them to react quickly (surges often last just millionths of a second) yet endure high voltages.


The three basic things to look for when choosing a surge suppressor are:

UL 1449 rating. This Underwriters Laboratories rating is the standard for surge suppressors. It ensures the suppressor can reduce a 6,000V surge, for example, to a harmless 330 to 400V one. (Though some makers claim their devices will allow only 100 volts to reach electronic devices, the best recognized rating is 330 volts.)

An internal fuse. When suppressors are overwhelmed by a surge of power that lasts more than the few milliseconds they're designed to handle, an internal fuse breaks the circuit, preventing the surge from reaching connected devices.

A solid warranty. "A warranty can tell you what the manufacturer thinks of the protection its suppressors offer," says Brad Hendricks, product manager for power at Kensington Microware Limited, a San Mateo, California-based manufacturer. Look for a written warranty from an established company that will cover the cost of any damage to the equipment connected to the suppressor. But remember, many manufacturers require you to prove the suppressor was faulty before they pay up.

Depending on what equipment you're protecting, you might want some added bells and whistles:

Fax/modem and coaxial protection. One of the most common ways a power surge enters your home is via a phone line connected to a computer. The coaxial cable on a television set is another common entry point. So if you've got cable or a satellite dish, or if you surf the Net, consider a suppressor with this type of protection.

For a home computer equipped with a modem, use a suppressor with modem and AC protection in one unit. The American Power Conversion SurgeArrest Per7T ($39.95) combines modem and AC protection. A light tells you when the protection is no longer working.

For home-theater equipment, choose a suppressor that protects the coax line for cable TV, rooftop antenna, and downline television sets (like the second set in your bedroom). Since home theaters draw a lot of energy, look for a unit that turns on equipment sequentially to prevent a "thump" in your speakers. Satellite TV, coax, control/data lines, and the downline phone connection for pay-per-view hookup also need protection. The Panamax Max 6 Allpath ($79) can be customized with add-on modules to protect these and nearly every other electrical source. Modules cost $39 to $65 depending on application.

Noise filters. Suppressors from Panamax, Tripp Lite, and others have noise-reduction circuitry to eliminate electromagnetic interference. The Tripp Lite Isobar 6 ($99.95) offers AC protection and three levels of noise protection, with increased noise filtering for computers.


You don't have to hook up every item with a plug to a surge suppressor. While many toaster ovens, blenders, and coffee makers have computer chips that can be harmed by a power surge, most of these appliances are relatively inexpensive to replace. "If your microwave costs $100 to replace, buying a surge suppressor that costs $30 or $40 to protect it is excessive," says Kensington's Hendricks.

Also remember that dishwashers, refrigerators, air conditioners, and other equipment with large motors generally don't need surge protection. But check your homeowner's insurance policy to be sure these devices are covered for lightning damage. Some other items to check before using any surge suppressor include:

Verifying that the three-hole wall socket it plugs into is grounded so the suppressor can dump excess voltage to ground. If you aren't sure, use an electrical tester to run a check. The Accu-Test II ($115) from Ecos Electronics gets the nod from electricians. It's a comprehensive tester that can check for 125 different combinations of AC wiring errors from outlets in the home.

Checking the circuits in your house — if they have not already marked on the service panel (usually in the basement, garage or a closet) — to see which circuits carry appliances that draw high current. You can perform a check by throwing circuit breakers selectively to isolate each circuit and the outlets and devices connected to it. Avoid plugging sensitive equipment like computers into circuits that carry heavy-draw/heavy interference appliances such as refrigerators and microwave ovens.

And again, use common sense. Protect your big investments, but don't pay extra to protect inexpensive ones. Except for the teenager who has a hot date planned, few folks would consider a fried blow-dryer a cataclysmic loss.

<p>The Square D QO2175SB surge arrestor plugs directly into the breaker panel to reduce higher-level surges than surge suppressors can handle.</p>

The Square D QO2175SB surge arrestor plugs directly into the breaker panel to reduce higher-level surges than surge suppressors can handle.

Photo by Joshua McHugh

Big-Spike Protection

Surge suppressors are made to protect equipment that's particularly sensitive to moderate surges. But there are systems that will protect your other devices from bigger jolts.

System Protection. If you live in an area that experiences frequent surges, consider a surge arrestor. Installed at the service panel, an

arrestor uses the same technology as a suppressor does, but it's designed to handle higher loads and prevent damage in a broader way.

"Arrestors are designed to protect light switches, appliance motors, the circuit breaker box, and all the wiring in a home," says Gary Shireman, section leader for application engineering support at the Lexington, Kentucky-based Square D Company. "These devices can generally withstand higher voltage spikes." That's why surge arrestors take up where surge suppressors leave off. Good suppressors can cut down surges to 330V; most arrestors don't reduce surges much below 600V.

"An arrestor is important because it can reduce a much higher-level surge than most suppressors can handle," says Shireman. "But it's doesn't replace a surge suppressor-they work hand in hand."

Arrestors should conform to the ANSI/IEEE C62.11 or C62.1 standard. (Obtain a list of Underwriters Laboratories-listed arrestors from UL Data Service) Expect to spend $50 to $250. Unless you have advanced electrical skills, figure on hiring a licensed electrician for the installation — about another $100.

Thunderbolt Insurance. There's an even higher level of protection if you live in a lightning-prone area: lightning protection. These systems work with a surge arrestor and surge suppressors, and consist of lightning rods placed at intervals around your home. The rods are connected by cables that allow the current to travel to ground. "Prices vary according the size of the home, but a $1,000-to-$2,000 system is adequate for most," says Norm Violette, an electrical engineer at the Fall Church, Virginia-based Violette Engineering Corp.

Lightning protection is specialized work that involves a lot of roof climbing; most folks turn it over to a pro. However, check with UL before hiring a lightning-protection company. UL keeps a list of installers certified under its Lightning Protection Installation Program. Certified installers are also required to connect a surge arrestor.