If lightning strikes an unprotected home, the power surge is likely to be carried throughout the electrical wiring, frying delicate circuits in computers, stereo systems, telephones, and other electronic gear, destroying appliances, and possibly harming anyone who happens to be touching one of these otherwise benign devices. But electrical surges occur more frequently than most homeowners know, and not only as a result of a lightning strike.
Most surges, in fact, are caused by routine electrical switching operations at local utilities or nearby industrial facilities. Most homes typically experience up to 2,000 surges a year - an average of six per day. Unless your home is adequately protected, these spikes can damage sensitive electronic circuits, including those in computers, telephones, televisions and other home-entertainment equipment, and electronic controls.
A surge - or a "transient overvoltage abnormality," as an engineer would describe it - can overwhelm ordinary defenses like fuses or circuit breakers. Every home needs more protection from surges, especially if it's in an area where thunderstorms frequently occur. Fortunately, devices are available to safeguard not only your incoming electrical line, but also other valuable entry points such as telephone lines and television cable or antenna wiring.
A three-tiered strategy is recommended. The first line of defense includes lightning and transient high-voltage spike protection devices, known as "transient voltage surge suppressors (TVSS)." They are commonly used in agricultural, commercial and industrial buildings, and inexpensive versions are available for homes, as well. Installed at the electrical meter or service panel, these devices react automatically to suppress any incoming voltage surge, reducing the power to a lower voltage level by diverting part of it to the ground. They protect the entire electrical system "downstream" of the installation point.
Because very powerful surges, especially lightning, can strike any incoming wiring, experts suggest buying a multiple-connection unit that simultaneously protects telephone, coaxial cable and antenna wiring for televisions, stereos and home computers.
The second level of defense includes point-of-use surge protectors, which include the familiar plug-strips with built-in circuit breakers. Although these devices are not strong enough to resist a mega-voltage spike, they provide some backup protection for any excess power that manages to get past the main surge arrester. Make sure all the surge suppressors in your home are labeled to indicate that they meet Underwriters Laboratories (UL) 1449 standard, Edition 2.
Electricians caution, however, that these devices are of little value if a home's grounding system is not equal to the task. Many homes, both newer and older, are insufficiently grounded.
Because surge protectors use this path to direct excess energy safely away from the home and its occupants, it's important to have a professional check your home's grounding system before installing a surge arrester. If necessary, adding "supplemental grounding electrodes" such as copper rods would be a simple, cost-effective solution.