Whole-house surge suppressors can save appliances, electronics

Q: I have had a couple of electronic items burn out from lightning during thunderstorms. Other items don't seem to last as long as they should. Will a whole-house surge suppressor protect them?

A: The highest-voltage electrical surge your house wiring will ever experience is from a direct lightning strike, but that is a rare event. Actually, there are other smaller surges that cause most of the damage to electrical devices as compared to instantaneous damage from a lightning strike.

People often think of computers, televisions, media equipment, etc., as most susceptible to damage from a voltage surge, but many more items in a typical house are also at risk. Almost every modern electric appliance (clothes washer, dishwasher, range, etc.) is full of electronics that high-voltage electric surges may damage. Even my electric blanket is full of electronic temperature controls.

A whole-house surge suppressor can protect your electronic items from most surges, but don't expect it to protect everything against a direct lightning strike. The amount of energy in just one lightning bolt is tremendous and can easily reach 100 million volts. Some surge suppressors include a $10,000 to $250,000 warranty to cover any electronic equipment damaged by a surge that gets through.

The majority of the voltage surges in your house wiring are much smaller ones that often are created when an electric motor switches off. These inductive-induced surges may come from a commercial business nearby or even from your own refrigerator or vacuum cleaner motor switching off. They slowly degrade the wire insulation or electronics components until they fail.

There are many types of whole-house surge suppressors available for use with residential wiring that can absorb the surge and leak it off to ground. They are wired directly into the electrical system and automatically detect and dissipate a surge before it reaches a high enough level for damage. The best ones react to a voltage surge in less than one nanosecond.

One very effective type of surge suppressor mounts under the electric meter. This type has to be installed professionally and is often sold or leased by the utility company because the electric meter is removed during installation. This design can handle a large surge.

Another type, which I use in my house, mounts under the circuit breaker box. This is connected to the house wiring by just a couple of wires and will protect one entire circuit.

A whole-house surge suppressor built into a circuit breaker that fits in a standard breaker panel is also available for simpler installation. Still, have it professionally installed.

Various surge suppressors provide different levels of surge protection. Most use the same technology of MOVs (metal oxide varistors) to absorb a voltage surge and rapidly dissipate it. A physically larger MOV can handle a larger surge without burning out. If the MOV gets fried, it just becomes ineffective and will not affect your electric power. It must be replaced to provide protection.

A key performance specification to consider when selecting a whole-house surge suppressor is the maximum surge current energy dissipation in joules. A joules rating above 1,000 should be adequate and provide a long life for a residence. A surge above this will burn out the MOV. Some larger ones can handle several thousand joules without damage.

Clamping or let-through voltage is the voltage level where the surge suppressor begins to block and dissipate the surge. The UL rating levels range from 330 volts to 600 volts. A lower clamping voltage should provide better surge protection.

There often is an LED indicator to indicate if a surge has burned out the MOV and some also include an audible alarm. Even though the unit looks the same and the electricity still flows, there is no surge protection after the MOV is damaged.

The most important tip for protecting your electrical equipment is to unplug everything possible during a thunderstorm. A strong voltage surge can jump across an open switch so don't just switch things off. For sensitive or expensive electronic equipment, use a separate point-of-use surge suppressors for each one. Although a UPS (uninterruptible power supply) backup unit provides some level of surge protection, just that alone is not enough.

The following companies offer efficient surge suppressors: Asco Power, (800) 288-6169, www.ascopower.com; Belkin, (800) 223-5546, www.belkin.com; Eaton, (800) 386-1911, www.eaton.com; Intermatic, (800) 391-4555, www.intermatic.com; and Meter-Treater, (800) 638-3788, www.metertreater.com.

Q: I plan to use my fireplace often this winter, but it doesn't always draw well and the room gets smoky. I have heard that nailing a 5-inch board across the top of the opening will help it draw.

A: The relationship of the opening width and height dimensions are important for a fireplace to draw well. Many fireplaces are designed with a tall opening more for aesthetics than function and they backdraft like yours.

Reducing the height by 5 inches often helps. DO NOT use a wood board. Use a steel or aluminum angle. A wood board would be a fire hazard, and your entire house may become one big fireplace.

• Write to James Dulley at 6906 Royalgreen Drive, Cincinnati, OH 45244 or visit dulley.com.