Protecting Against Lightning

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Although lightning is not attracted to tall metal objects, such as a wind generator tower, as is commonly thought, it is important to install lightning protection. Grounding rods attached to the tower bleed off the static charge created as air masses move across the Earth’s surface. They’ll reduce the likelihood of a direct strike. Ground rods are eight-foot long copper-coated rods. They are driven into the ground at the base of the wind turbine tower. For details, contact a local installer or your turbine/tower manufacturer. (For more on the subject, see Mick Sagrillo’s article “Residential Wind Turbines and Lightning,” available online at renewwisconsin.org/wind/Toolbox-Fact%20Sheets/Lightning.pdf.)

Grounding a tower minimizes lightning strikes, but does not guarantee that lightning will not strike your tower. Backup is
needed in the form of lightning arrestors. Lightning arrestors “bleed off ” electricity in case of a direct or nearby strike, protecting sensitive equipment. A professional installer will provide recommendations.

Surge arrestors should also be installed on the electrical wire running down the tower and the utility wiring for grid-tied systems. They protect against surges of electricity induced in the wire by lightning strikes. The surge protectors on the utility side of the system protect against lightning strikes in utility lines, which are much more frequent than on properly grounded wind turbine towers.

While protecting against direct lightning strikes is important, nearby strikes pose the gravest danger to a wind system. When lightning strikes the ground near a home, it creates an electrical current in the atmosphere and/or the ground. This current creates a voltage wave that resembles ripples in a quiet pond after a pebble is dropped into it. If one of these waves crosses a conductor like a wind generator tower or buried wires, an electrical current will be created (induced) in the conductor. This current can fry sensitive electronic components of a wind system. Surge protectors in a wind system will help protect against this phenomenon.