What causes power surges

Most people worry about a power surge being caused by something outside of the house, like a lightning strike or a downed power line. While lightning is the most dangerous cause of surges, it’s far from the most common. According to the NEMA Surge Protection Institute, 60% to 80% of power surges start inside the home, typically from major appliances and systems that cycle on and off, such as air conditioners, refrigerators, and clothes dryers. “It can happen all day long,” says Jessaca Townsend, residential product manager for Advanced Protective Technologies, a Tampa, Fla.-based manufacturer of surge protectors.

Over time, those fluctuations take a cumulative toll on sensitive electronics, such as plasma TVs, computer equipment, microwaves, and smart appliances, causing delicate circuits to malfunction or burn out prematurely.

Whole-house surge protection

Since power surges don’t present a fire hazard, protective devices aren’t required by building codes or homeowner’s insurance carriers. But everyone from the National Fire Protection Association to the Institute for Business and Home Safety recommends them.

The good news is that protection is readily available, and even the top-of-the-line solutions are affordable. The gold standard is a two-tiered system: a whole-house surge protective device, or SPD, installed at the circuit breaker box, and plug-in SPDs on individual outlets.

The circuit-breaker unit runs in the $200 to $300 range and is a simple matter for an electrician to install. Wes Carver, president of Wes Carver Electrical Contractors in Lansdale, Pa., charges $295 for a whole-house surge protector, including installation.

A whole-house SPD can protect against up to 40,000 amps of current flowing into your home from the outside; normal household power is 200 to 300 amps. When a sudden surge occurs, such as from a lightning strike or damage to a power line, the device detects the excess current and safely diverts it through the house’s grounding path.

In certain parts of the country, your power company may offer whole-house surge protection at the electrical meter, either for a one-time charge or billed monthly. Florida Power & Light Electrical Services, for example, charges $9.95 a month for meter-based surge protection that covers major appliances and motor-driven items, such as air conditioning systems. “It can withstand up to 57,000 amps of current,” says Joe Nestor, FP&L Electrical Services product manager for power-quality products. The monthly fee includes an insurance policy that covers up to $5,000 per damaged or destroyed item if the device fails.

Plug-in protection

For the most sensitive electronics, such as computers and home entertainment systems, a second layer of protection is recommended in the form of point-of-use SPDs. You can get them from any electronics retailer. A quality point-of-use SPD starts at about $30 and comes with a warranty to replace damaged equipment if the device fails.

Make sure any device you buy meets these criteria:

* Rated by Underwriters Laboratories. The standard category is 1449.

* Has a clamping voltage of 400 volts or less. That’s the amount of surge that will trigger the device to divert power from your equipment to the electrical ground. The lower the number the better, says John Drengenberg, consumer safety director for Underwriters Laboratories, which tests the devices.

* Absorbs 600 joules of energy or more. Unless you’re an engineer, don’t worry about the definition of joules. Just know that 600 is the minimum.

* Protects all incoming lines. Surges can enter the house through cable and phone lines, too, so if you are using electrical equipment that’s also plugged into a cable or phone jack, such as a fax machine or satellite TV box, make sure the SPD has inputs for all three.

* Has an indicator light. That way you can see at a glance if it has stopped functioning.

No surge-protection device is foolproof; if your house takes a direct hit from lightning, only luck and good karma will keep anything plugged into a power source from being obliterated. But weighed against the damage even everyday power fluctuations can cause, whole-house surge protection is an investment well worth the cost.