Whole House Surge Protectors?


Don’t count on power strips to safeguard your home and fragile electronics.

Many homeowners believe that adequate surge protection begins and ends with plugging their computer into a power strip. Unfortunately, that's seldom the case. First of all, not all surge protectors live up to their name; some are little more than glorified extension cords. Second, a surge will follow any wire into a house — phone and cable lines included — and threaten fax and answering machines, televisions, satellite systems, computers, and modems. And third, as the owners in the Acton remodel discovered, delicate electronic circuitry has proliferated throughout our homes, leaving common appliances as vulnerable as computers to the effects of surges.

Two Types of Surges
A power surge may last for only a few millionths of a second, but at its worst, it carries tens of thousands of volts, enough to fry circuit boards, crash hard drives, and ruin DVD and home-entertainment systems. Lightning-induced surges are the most powerful and most feared: A 200,000-amp jolt crashing through a power line will burn standard 20-amp wiring like a light bulb filament. But a lightning strike has to be less than a mile from the house to cause harm, and in fact most surge-related damage is not caused by lightning. 

The Best Defense
Guarding against surges requires a two-pronged approach: a whole-house suppressor to tame the big, dangerous power spikes and an individual circuit (or "plug-in") surge suppressor for vulnerable appliances and electronic devices. Both types essentially act like pressure-relief valves. Normally they just sit there, allowing electric current to flow through them. But with higher-than-normal voltage, the devices instantly divert excess voltage to the ground wire. (The best ones react in less than a nanosecond.) As soon as voltage levels return to normal, the flow of electricity is restored, unless the surge was big enough to melt the fuse built into some units. 


Typically, whole-house suppressors are hard-wired to the service panel, a process that takes a licensed electrician about two hours. Whole-house systems should be rated to stop a 40,000-amp surge, at minimum. Features to look for include thermal fuses, and lights or alarms that indicate when a device has taken a hit. Protection for an average house with 200-amp service will run about $500 — including a couple of hours of an electrician's labor. Separate but smaller whole-house units are recommended for the phone and cable lines. These protect fax and answering machines, televisions, and modems. 
By themselves, whole-house suppressors can't stop surges completely; up to 15 percent of excess voltage may leak by. That's where "plug-in" surge protectors come in. These buffers between individual appliances and wall outlets come in a bewildering array of options and prices. They range from $70 units not much bigger than a computer mouse to $350 units the size of a pizza box that guards all the components in a home theater. But most plug-in models fall into three basic categories: the familiar multi-outlet power strip; the multitasking surge station that can handle phone and cable jacks as well as power cords; and the UPS (uninterruptible power supply), which completely cleanses electric power of random fluctuations and provides a short-term battery backup in case the power dips or goes out entirely. Expect to pay between $20 and $70 for a quality power strip or surge station and from $100 to $250 for a UPS.

Buying Plug-in Protection
Before buying a plug-in unit, check that it does the following: 

•Meets UL Standard 1449 (second edition).
•Has a clamping voltage — the amount that triggers the diversion of electricity to the ground — of 400 volts or less. The lower the number, the better the protection.
•Absorbs at least 600 joules of energy.
•Protects all three incoming lines: hot, neutral, and ground. Look for "L-N, L-G, N-G" (line to neutral, line to ground, neutral to ground) on the product's spec sheet.
•Stops functioning when its circuits are damaged by a surge.

Both whole-house and plug-in types can get zapped without your knowing it; look for indicator lights that signal when a unit no longer works.

Written by Jim Collins, This Old House Magazine



If you have a question, comment, or home tip, send your letter to Home Tips, Christian Building Inspectors, Inc., 3697 Habersham Lane, Duluth, Georgia 30096. You can email your questions to us at rod@cbiga.com. We reserve the right to edit questions for length.

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