Lightning Protection for the Amateur Radio Operator’s

Lightning Protection for the Amateur Radio Operator’s Home

Lightning protection is a safe investment for any station.

Jennifer Morgan and Michael Chusid

It is every radio operator’s worst nightmare. Millions of volts suddenly leap out of the sky, striking your home, antenna, or other conductive surfaces. Billions of watts race down transmission lines or through the building’s structure, destroying your transmitter, amplifier, receiver, or other elements of your radio apparatus. Your prized station is now just trash. And if you happen to be online when the “signal” comes in, you could be toast, too!

Congratulations — you have just become a victim of one of the approximately 25 million lightning strikes that occur in the United States each year. You have learned the hard way that in the contest between lightning and your equipment, lightning usually wins.

An excellent, three-part article on “Lightning Protection for the Amateur Radio Station,” by Ron Block, KB2UYT (now NR2B), was published in the June, July, and August 2002 issues of QST and provides sound guidelines for protecting your station.1 But as stated in Part 1 of the series, the goal is “to establish a ‘zone of protection’ within the radio room, as opposed to the whole house or building.” The particulars of protecting the unique electronics in a radio setup are beyond the scope of this article, and a specialist may need to be consulted. This article recommends that the protection of your equipment begins with protecting a seemingly minor accessory to your station — your home.

Lightning Protection for the Amateur Radio Operator's Home

 

Special Risks for the Amateur

Lightning strikes pose special risks for the Amateur Radio operator. To increase signal coverage, operators often place their antennas as high as possible — for example, on towers or rooftops — increasing the risk of being at the receiving end of a strike.

When an enthusiastic amateur upgrades their station, he or she inadvertently becomes more vulnerable. That’s because, as radio equipment improves, electronic circuits become miniaturized and, thereby, more susceptible to damage from energy surges.

Amateur Radio operators take pride in being of service during emergencies. Unfortunately, lightning strikes occur during hurricanes, tornados, forest fires, floods, blizzards, and other extreme weather events. Emergencies are the exact time that Amateur Radio operators are needed the most, and the worst time to discover latent damage or degradation.

Unfortunately, several myths about lightning protection come into play.

Myth 1:1 don’t need a lightning protection system (LPS) because lightning strikes are rare.

According to the Insurance Information Institute, claims for lightning losses cost nearly a billion dollars in 2015. From 2010 to 2015, the average cost per claim rose 64%. These figures understate losses because much damage is not reported (or is not included because of deductibles), or is attributed to equipment malfunction instead of lightning. In addition, the frequency of lightning strikes appears to be increasing.

Keep in mind that low risk is not the same as no risk. Tennessee generally has a lower number of lightning strikes than Florida, but still had $24 million in homeowner lightning damage claims in 2015. Even in low-risk southern California, lightning storms caused deaths and injuries, set fire to homes, and knocked out power to Los Angeles International Airport — even at the height of last year’s drought.

Myth 2: I don’t need an LPS because my antenna is not the tallest structure around.

Lightning is going to go wherever it wants to. Lightning protection standards treat lightning as if it were a 300-foot-diameter sphere rolled across the surface of a building (see Figure 1). Any place the sphere contacts the building is a location where lightning can attach. The point of contact might be your antenna, but could just as readily be another point on the house. Moreover, lightning need not directly strike a structure to cause damage. The energy of a lightning strike can “side flash” from one object to another. Also, lightning can travel to your structure through metal objects (such as wire fences, plumbing, and cables) and even through the ground.

Myth 3: I don’t need an LPS because I connected my antenna to a metal ground rod.

An LPS is more than just a wire to a ground rod (see Figure 2). The Insurance Information Institute cautions:

Keep in mind lightning protection system design and installation is complex and not a do-it-yourself project. Installation is not typically within the scope of expertise held by general contractors, roofers, or even electricians, which is why the work is typically subcontracted out to specialists.2

Lightning Protection Fundamentals

Lightning typically begins within a cloud, where ice particles collide and generate static electricity. When the charge within the cloud grows sufficiently, the electrical insulating properties of air fail, and an ionized conductive channel to the opposite charge is established. The rapid discharge of electricity along this channel is lightning, both cloud-to-cloud and cloud-to-ground.

The power of a lightning strike is daunting. In 0.2 seconds, the air around the conductive channel can heat up to 50,000°F. An object in the path of a lightning strike may be subjected to as much as 3 million volts.

Lightning seeks the path of least resistance to ground. If the path is through your home, it could cause fire or structural damage. If it is through you, it could cause serious injury or death. And if it is through your equipment, you’re likely to lose that equipment (see Figure 4).

Lightning protection systems work by creating an adequately sized, low-resistance path for lightning to flow around a structure into the Earth. An LPS should be designed and installed in compliance with the following standards (see Figure 3), based on technologies and principles that have been proven over the past 200 years:

view the full-text document Reprinted with permission from June 2017 QST

Lightning Protection for the Amateur Radio Operator’s Home

 

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