Surge Protection for Your Home Wiring System in the San Jose Area
Not long ago, electrical contractor Allen Gallant was about halfway through the job of completely rewiring a 3,200-square-foot house in Acton, Massachusetts, when the owners decided to save some money and not install whole-house protection against power surges. Sure enough, soon after the house was finished, Gallant got a phone call from the distressed owners: Lightning had struck a utility pole near their house, sending a tidal wave of voltage through the wires, past the main breaker panel, and into the house. “It burned out the motherboard in the Sub-Zero refrigerator, fried the temperature controls in the double-wall oven, killed six dimmers, two computers, and every GFCI plug in the house,” Gallant says. “It was an $11,000 loss.”
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 pro-liferated throughout our homes, leaving common appliances as vulnerable as computers to the effects 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.
Far more common, if not as dramatic, are surges caused by downed power lines, sudden changes in electricity use by a nearby factory, or even the cycling on and off of laser printers, electric dryers, air conditioners, refrigerators, and other energy-sucking devices in the home. The damage inflicted by these minor power fluctuations can be instantaneous — but may not show up for some time. “You might not even notice it,” says Andy Ligor, a consultant with A.M.I. Systems Inc., a firm that installs both residential and commercial surge-protection systems. “Then a year or so later your microwave stops working.”
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 guard 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.
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.
Even the best surge suppressor can’t do its job if the house wiring isn’t properly grounded; there has to be a single way for the diverted electricity to go. “Without a good ground, the current may follow another wire and end up inside your modem or fax machine,” says Tom Plesich, director of business development at Innovative Technology, a maker of surge-suppression equipment. Also, avoid plugging surge-sensitive electronic devices into the same power strip with laser printers, air conditioners, or other appliances with large motor loads. These produce their own low-level power surges that will affect all the devices sharing the strip.
Insurance companies don’t typically give discounts for surge-protected homes, but investing in protection may very well pay for itself, and then some. That’s what the owners of the house in Acton discovered — too late. When Allen Gallant returned to the surge-damaged site, he spent an hour and a half installing a whole-house system that included a panel-mounted, whole-house surge suppressor and similar devices for phone and cable lines. The new wall ovens ($3,000) are now safe from surges, as are the repaired Sub-Zero refrigerator ($1,200) and all of the house’s other electronics. Total bill from Gallant: $940.
Article reprint from This Old House magazine.
Call Pacific Coast Electricians, Inc. at 408-212-0230.