Resisting the Surge

Power surges caused by lightning can wreak a significant amount of damage to a home’s wiring and electronics if the house is not properly protected. According to the Insurance Information Institute, both the number of homeowner claims for damage due to lightning as well as the average payout have both increased markedly in recent years.

The most essential element in protecting a house from power surges is correct grounding. Electricity in a wire is comparable to water running through a hose. Quick increases in flow or pressure (surges) will cause major damage at the end of the line if there is no where for the water (electricity) to drain. Luckily for us, our clay soils and high water table provide a very large conductive “drain” to dissipate electrical surges. Running a ground wire from a home’s wiring provides an outlet for the larger part of the surge to drain before it reaches then entire electrical system.

Any line carrying an electrical signal, including phone lines and coaxial cables (TV, satellite dish lines, etc.) is a conduit for an electrical surge. It is important that all of the lines into the house (electrical, phone, coaxial cable) be grounded on the same element. Multiple grounding rods (a common installation on older houses) create differences in pressure/current that also cause problems. The present building code requires that all house wiring be grounded on the same rod to address this issue. Be sure to regularly check the ground rod and wiring – during my most recent inspection, I discovered the coaxial ground had been neatly clipped off by my weed eater.

Another important element of protection is a surge suppression system installed in-line with all electrical systems including the circuit panel, phone system and coaxial cable. The circuit breakers in our homes are not designed to handle supply-side surges – they only manage the draw from our indoor appliances. Surge suppression systems installed at the electrical panel are designed to handle any of the excess current that makes it past the ground element.

Even though most of us relay on point-of-use surge suppressors to keep our electronics protected, they are the last (and weakest) line of defense. In reality, there is a wide variety in how much protection they provide and for how long. Cheaper ($5-$10) units are little more than multi-outlet plugs and offer almost no protection. More expensive suppressors afford better security but they too will burn out when exposed to repeated surges and spikes. When relying on a point-of-use surge protector, do your research and be sure that you are getting the amount of security that matches your investment.

A full-house, professionally installed lightning protection system typically costs $1,500. These systems come with a 25-year guarantee and eliminate the need for point-of-use surge protectors.

This blog was written for Paul LaGrange’s BuildWrite website and was originally posted on August 22, 2009.

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