Surviving the Sky’s Worst Day: Lightning Protection for Radio Equipment — Annotated Notes & Key Takeaways

Lightning protection for radio equipment is not a single gadget you buy, plug in, and forget. The material makes that clear from the start. An antenna is often an excellent lightning attractor almost by design, and the equipment attached to it sits at the end of a long conductive path that can carry an enormous amount of energy. The central message is that protecting gear means thinking in systems: where current enters, where it leaves, how grounds are bonded, and what happens when a strike is nearby rather than direct. The most dangerous mistake is not doing nothing. It is doing a few things halfway and creating a setup that invites current to travel through the very equipment you meant to protect.
 

I found the strongest parts of the material were the ones that explained why a seemingly reasonable grounding choice can backfire. The weakest parts were where personal experience or broad claims took over from clear engineering logic. Still, as a set of notes on lightning protection, it offers a useful map of the problem and a few hard rules that keep reappearing.
 

The Three Rules That Keep Coming Back in Lightning Protection

The material boils the problem down to three requirements that must all be satisfied together. First, make good, low-impedance connections to Earth. Second, bond all Earth connections together with a low-impedance path. Third, give protected equipment only a single point of entry. Doing only one or two of these can leave you worse off than before, because lightning current is not polite. It will find the path you accidentally created, even if that path runs through a radio, a computer, or a piece of test gear.
 

Low-impedance connections to Earth

The first rule is the one most people already know, at least in outline. You want long ground rods, at least eight feet, and more than one if possible. The rods should be spaced about as far apart as they are deep. A big direct strike can involve currents well over 100,000 amperes. That is not a typo. At that level, conductors need to be fat enough not to be vaporized. Lightning is also an extremely fast pulse, which means it behaves like high-frequency energy. Because of skin effect, wide strapping is often better than round wire. The path should be as short and straight as possible to keep resistance and inductance low. A coiled or sharply bent ground conductor is not doing you any favors.
 

That part is fairly intuitive. The trouble starts when people treat one ground rod as a complete solution. A single rod may measure acceptably for ordinary electrical safety, but lightning is not an ordinary electrical event. The goal is not just to have “a ground.” The goal is to have a low-impedance path that can carry a massive, fast surge without developing dangerous voltages along the way.
 

Bond all grounds together

The second rule is where the material gets more interesting, and where a lot of amateur installations go wrong. The current from a strike is so large that it does not simply disappear into the nearest grounding rod. Earth itself is not a perfect conductor. Even when lightning hits an empty field, significant voltage gradients can appear some distance away from the strike point. The material gives the example of a tree that was struck, with an arc emerging from the ground about twenty feet away and traveling through a Beverage antenna. That image stuck with me. It shows that “ground” is not a single quiet reference point during a strike. Different parts of the ground can be at very different potentials for a brief, violent moment.
 

If your station has multiple connections to Earth, or even things close to Earth, lightning currents will find a way to those points. They may flow through station equipment. They may arc across water pipes, HVAC ducting, or the wood and concrete of a home, none of which are great insulators under those conditions. Bonding all the grounds together with heavy wire gives the current an intentional place to go. It creates a path that is much more attractive than the random path through your gear.
 

Most building and fire codes require this bonding for exactly this reason. The material treats it as non-negotiable. If you have a tower ground, an electrical service ground, a phone or cable ground, and a separate shack ground, and they are not bonded together with a substantial conductor, you have built a system that can develop large voltage differences during a strike. Those voltage differences will drive current through anything that bridges them. Your radio can easily become that bridge.
 

One entry point only

The third rule is perhaps the most neglected: protected equipment should have only a single point of entry. If there are multiple points of entry, lightning current can enter at one point and exit at another. Between those two points, there will be a voltage gradient. Where there is a voltage gradient, there is current. Where there is current, things break.
 

A common amateur setup has a grounding rod at the mast or tower, another at the point where the feedline enters the shack, and the ordinary electrical service ground somewhere else. The material describes this as a poor grounding system, and it even points to a diagram of the bad configuration. When lightning strikes the power lines, some of the current goes to ground through the additional ground at the tower or shack entrance. On its way there, it may pass through the equipment. When lightning strikes the tower, the same problem happens in reverse. A naïve attempt at protection has made damage more likely, not less. Even a nearby strike might introduce enough voltage between the grounds to cook sensitive equipment.
 

There is a popular bit of advice that says you should disconnect the feedline during a storm. The material points out a flaw in that advice. In some setups, disconnecting the feedline leaves an extra ground still connected. That violates the assumption behind the advice. The equipment may still be connected to power and to a separate ground, so the single-point-of-entry principle is still broken. Disconnecting one cable is not a magic shield if the grounding layout is wrong.
 

What a Serious Installation Looks Like

The ideal approach described in the material is ambitious. It starts with the base of the tower or mast. You want a large field of radials and many ground rods, spaced over a wide area and bonded together with wide copper strap. The shields of all coax feedlines are bonded to this ground.

Next, inspect where electrical, CATV, and phone service enter the building. Make sure that ground is in good shape and has sufficiently low impedance. Lightning can strike utility lines too. You want that path to take a good part of the strike current, reducing the load on other parts of the system.
 

Then surround the entire house with wide copper strap, with a hefty ground rod every eight feet or so. The strap puts all the ground rods in parallel and lowers the overall ground impedance. The ring around the house also acts like a two-dimensional Faraday cage. It reduces the electric potential difference between any two points on the ground inside the ring. That is a clever way to think about it. You are not shielding the whole building with metal mesh. You are giving the ground itself a common reference.
 

Bond the tower and house ground systems together with wide copper strap. Any current caused by a voltage between them should favor that strap over your feedlines. Utility grounds should also be part of this system. This is often required by fire codes because it reduces the chance of an electrical arc between ground systems. Such an arc is especially likely if there is a good conductor that goes most of the way but not quite all the way between the grounds. A disconnected feedline is a perfect example.
 

Every cable that enters the shack should pass through a big, fat copper plate. That includes mains wiring, control lines for rotators, ethernet cables, and anything else. The plate is connected with a wide, short, straight connection to the ground running around the house. Each cable goes through protection devices such as gas discharge tubes or MOVs. Conductors that should be grounded, like feedline shields and AC safety ground, are bolted directly to the grounding panel. By making this the single point of entry, all protected equipment stays at the same electric potential.
 

With a setup like that, the material says you can confidently leave feedlines connected in a storm and survive direct strikes to the antennas. The house may even be less likely to be damaged by lightning than ordinary residential construction. A direct strike may damage exterior components, burn insulation, or melt thin-gauge wires. Equipment inside is described as quite safe. That is a strong claim, but it follows from the single-point bonding logic. The system is designed so that there is no convenient path for strike current to travel through the sensitive gear.
 

The Smaller, Smarter Approach

Most people will not install such an extensive protection scheme. The material acknowledges that. If you do not have a tall tower, or you live where lightning is rare, the cost and effort may be hard to justify. In that case, the advice shifts from what you should do to what you should not do.
 

Do not create an extra ground. That is the key warning. If you are not going to build a full single-point bonded system, adding a separate shack ground can make things worse. It can create exactly the voltage difference that drives current through your equipment. Instead, address common-mode currents with baluns and proper antenna design. If you must have a ground, such as a vertical antenna installed at ground level, consider the ground part of the antenna rather than part of the station. Be sure to disconnect it in storm conditions.
 

I found this part practical but also frustrating. It is much easier to say “do not create an extra ground” than to know whether an existing setup already has one. The material does not give a simple checklist for every possible station layout. It gives principles. You have to apply them to your own situation. That is fair, but it leaves room for confusion.
 

Disconnecting, Surge Devices, and the Hard Limits

The material includes a more traditional recommendation: the surest way to protect radio gear is to disconnect it from power, from the antenna, from the computer, and even from ground. That is the belt-and-suspenders approach. It is also a hassle. And even that is not a guarantee. One account describes an enormous bolt of lightning striking a backyard. Three transceivers were involved. One rig was still connected to a computer, and both the computer and rig were smoldering. The other two rigs were fried despite being disconnected from power and antenna. The presumption was that the electromagnetic field from the lightning was powerful enough to destroy components inside the rigs. That is a sobering story. It suggests that if the strike is close enough, no amount of unplugging may save everything.
 

Surge protectors are another recurring theme. Companies make lightning surge protectors that install in the coax line and divert the strike to ground. Polyphaser is mentioned as well respected. MFJ makes lower-cost options. A discharge tube is suggested as a way to protect a rig from a close strike, along with a decent shack ground. But the material is not uniformly enthusiastic about these devices. One view says that simply installing a lightning surge protector in the feedline is likely to do little to nothing. The very loud caveat that disconnecting is the only sure way is also challenged. The counterargument is that commercial broadcast stations do not detach their antennas for every storm. They remain on the air despite being in terrible locations for lightning exposure.
 

That counterargument is strong in principle, but it is not the whole story. Another part of the material notes that commercial TV and FM stations are indeed disabled by lightning strikes every year, sometimes multiple times a year. One major TV station and two FM stations serving large metropolitan areas went off the air for up to two weeks for antenna and transmitter repairs after strikes. The assumption is that these stations were designed by competent engineers who took all known and reasonable precautions. The conclusion is that it may be virtually impossible to completely protect equipment from a major lightning strike as long as the feedline is connected between the antenna and the equipment, and the equipment is connected to commercial power. The best hope is a proper ground system. Gas discharge tubes, surge protectors, TVSs, and spark gap devices available to the average ham are described as window dressing. They may bleed off static and reduce noise, and they may offer some front-end protection for a receiver, but they are not a guarantee.
 

There is also a discussion of nearby strikes and EMP. One comment notes that if lightning strikes close by, the electromagnetic pulse can still damage sensitive equipment. The suggested steps are to ground the antenna, unplug from power strips, short all input and output ports and plugs, and enclose equipment in a Faraday cage if you become fanatical. The response to that is interesting. Most damage from nearby strikes comes from strong voltage gradients over the ground or between the ground and things near it. Those gradients cause arcing, which effectively grounds things near the ground. You do not need a whole Faraday cage to protect against this. A ring of wide copper strap around a building will do. It forms a sort of two-dimensional Faraday cage. Commercial broadcast stations do exactly this, which is part of why they can stay on the air despite multiple strikes per year and never disconnecting the antennas. That is a useful correction. It moves the conversation away from exotic shielding and back to grounding and bonding.
 

Codes, Insurance, and the Unsettled Parts

The material brings in the National Electrical Code, specifically NEC 810, for installations in the United States. An article by Reeve is cited as covering the requirements well. The warning is blunt: failure to comply with NEC 810 is the number one reason ham radio operators in the US have fire insurance claims denied. It is also why some buy ARRL’s insurance policy. If you follow NEC 810 and get permits for your work, the insurance company is less likely to deny a fire claim. That is not just engineering advice. It is practical household advice.
 

The strongest limitation in the material is the tension between the ideal system and the impossibility of perfect protection. The ideal system, with a ring of copper around the house and a single point of entry, is described as capable of surviving direct strikes. Yet another part says that as long as the feedline and power are connected, complete protection from a major strike is virtually impossible. Those two claims are not necessarily contradictory. The ideal system is expensive, carefully built, and rare. The impossibility claim applies to ordinary installations. But the material does not fully resolve the difference. It leaves the reader to decide how much protection is worth buying.
 

Another unresolved point is the field operation angle. The original setting is amateur radio, and the opening question asks about keeping gear safe in the field. Most of the detailed advice is about home stations, towers, shacks, and house grounds. There is not much specific guidance for temporary field setups beyond not operating in a storm, disconnecting, and avoiding extra grounds. If you are operating from a tent or a park, the single-point-of-entry principle still matters, but the practical implementation is not spelled out. That is a gap.
 

The role of surge protectors also remains contested. One part treats them as nearly useless without a proper single-point system. Another part recommends them as part of a layered approach. The material does not provide test data or a clear decision rule. It gives experience, principles, and references. That is enough to guide a careful reader, but not enough to settle the argument.
 

What I Took Away

The most useful idea in the whole set of notes is that lightning protection is a system property, not a product. You can buy a surge protector, a ground rod, or a discharge tube, but if the grounds are not bonded and the equipment does not have a single point of entry, you may be building a path for current to flow through your gear. The three rules are simple to state and hard to follow: low-impedance earth connections, bonded grounds, and one entry point. If you cannot do all three, the material suggests you are often better off not adding a separate ground at all. Use baluns and antenna design to manage common-mode currents. Disconnect everything you can when a storm approaches. Accept that a close strike may still do damage.
 

For someone who could not read the original, the practical value is not a guarantee of safety. It is a way to ask better questions. Where does current enter my station? Where can it leave? Are my grounds bonded? Do I have more than one entry point? If the answer is yes, the next step is to fix that before buying another protector. Lightning protection is not about being fearless in a storm. It is about removing the accidental paths that turn a nearby strike into a direct hit on your equipment.