Protect Your Home From Lightning and Power Surge

Dollar figures for lightning and surge losses vary widely, but the best figures available estimate at least $2 billion in electrical and electronic equipment damage yearly — making lightning and surge a leading cause of electrical equipment failure.  Surge damage occurs when the normal electrical circuit is suddenly exposed to a large dose of energy. Lightning is the most obvious surge source, but normal utility switching operations or downed power lines
can generate surge too. Inside a building, surge may come from fax machines, copiers, air conditioners, elevators, or motor pumps.  Inside or outside, only lightning strikes within one mile of a structure are likely to damage electronic or electrical equipment. A surge protection device (SPD) is the best way to prevent or reduce damage caused from electrical surges and should be installed strategically outside and throughout the home. SPD’s are designed to redirect high-current surges to the ground and bypass equipment to limit the voltage that is impressed. Two different zones of defense should be used to provide maximum protection:
The first zone is the electric meter, where the utility power comes into the home. A “whole house SPD” can be installed directly into the meter box to reduce externally generated surges, including indirect lightning strikes on the line. Installing a whole house SPD requires the service of a professional electrician, and many local utility departments will install and/or lease units monthly. A whole house SPD rating should be between 20,000 and 40,000 amps. It should use fire proof and explosion proof polycarbonate glass-fiber reinforced enclosure with a matching mounting

The second zone of defense is inside the home because a SPD installed at the meter will not protect against internally generated surges. Appliances, such as microwaves, refrigerators, and garage door openers that have a power plug require a surge protection device that plugs into the wall. SPDs for appliances inside the home should not be rated less than 5,000 amps. Further, appliances that use two services, such as a television set with a cable wire and an electrical cord, may require a combination SPD that allows both a cable and a power connection. Computers, answering machines, satellite dish components and VCRs may also require combination protection.  Inside the home, SPD’s should be installed as close to the equipment as possible for maximum protection. Cable lengths should be as short and straight as possible to minimize the resistive path of the circuit to the ground. Also, the surge protectors should be equipped with indicators that show if the circuit is grounded and operating properly.  While nothing can prevent damage from a direct lightning strike, SPD’s can protect your valuable electronics and appliances from the most common source of damage— surge.

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