About Grounding

By Danny Horvat, E73M / N4EXA — antenna design engineer and founder of MyAntennas.com.

Grounding causes more confusion — and more wasted effort — than almost any other part of station building, because one word is being asked to do three different jobs. Hams run heavy cable to rods in the backyard believing they’re improving their signal, their safety, and their lightning protection all at once, when in reality they may be accomplishing none of the three. Let’s separate the jobs, because each has a different solution.

The Three Different “Grounds”

1. Electrical safety ground protects you from AC faults in your equipment. This is the job of your home’s electrical system — the third prong on your power cords, bonded to your service panel’s grounding electrode. Your radios get this automatically through their power cords. Nothing about your antenna changes it.

2. Lightning protection ground gives a strike energy a path to earth outside your home, before it reaches your equipment and, more importantly, you. This is what NEC-810 addresses, and it happens at the point your coax enters the building — not in the shack.

3. “RF ground” is the one hams chase hardest and need least. For the antennas we build, there is nothing for a shack ground to do: the EFHW’s return path is handled by the transformer design and the coax shield (see About Counterpoise), and feedline noise is handled by a common mode choke at the cable entrance (see About CMC). If your antenna system is properly built, your shack does not need an “RF ground” at all.

What NEC-810 Actually Requires

The National Electrical Code (Article 810) requires the shield of every coaxial cable to be grounded at the point where it enters your home, and — this is the part people miss — that ground must be bonded to your home’s main electrical grounding system. One unified system, everything at the same potential.

Why bonding matters: the goal is that during a fault or a nearby strike, everything in your house rises and falls in potential together. When everything is at the same potential, there is no voltage difference to drive current through your equipment — or through you. It’s basic Ohm’s law. A separate, unbonded ground rod for the radio system does the opposite: it creates two grounds at different potentials, and during a surge event the difference between them appears across whatever connects them — which is your coax, your radio, and your house wiring. An unbonded “extra” ground rod isn’t extra safety; it’s a hazard the code specifically exists to prevent.

The practical implementation: a grounding block or entry panel where the coax enters the house, with a short, heavy conductor bonded to the electrical service ground. This is also the natural home for lightning arresters — and the correct place for your common mode choke, before the shield contacts the grounding point. [DANNY: if you want, add a photo of your own entry panel here — a real-world example photo would make this page.]

The Long Ground Wire From the Shack: Why It Fails

Now the myth I spend the most time correcting. A second-floor shack, a heavy braid or strap running out the window and down to a ground rod: it looks responsible, and at DC or 60 Hz it is indeed a ground. At HF it is nothing of the sort.

At radio frequencies, a conductor many feet long is not a connection to earth — it is an impedance. Depending on its length relative to the operating wavelength, that wire can present tens or hundreds of ohms, and near a quarter wavelength it can transform the ground rod’s low impedance into a high impedance at the shack end — the exact opposite of what was intended. Worse, a wire carrying RF current radiates: your “ground wire” becomes part of the antenna system, radiating inside and alongside your house.

And if you have installed a common mode choke at the radio, that ground wire quietly defeats it — the noise current the choke was blocking simply flows around it via the chassis and the ground wire. This combination (choke at the radio plus ground wire to a rod) is the most common self-inflicted RFI configuration I see, and the fix is always the same: choke at the cable entrance, shield bonded there per NEC-810, and no long RF “ground” wire from the shack at all.

So What Should You Actually Do?

For a typical HF station running our antennas, the complete grounding picture is short:

At the cable entrance: ground the coax shield where it enters the home, bonded to your electrical service ground. Install your lightning arrestor there, and your CMC there if you need one. This single point does the lightning-protection job and the noise-management job at once.

In the shack: nothing special. Your equipment’s safety grounding comes through its power cords. You do not need a station ground bus tied to an outdoor rod for the antennas we build — and adding one can create the problems described above. (Stations with different antenna types, ladder-line tuners working against ground, or commercial installations have their own requirements — this page addresses typical coax-fed HF stations.)

At the antenna: also nothing. As covered in About Counterpoise, a ground rod at the EFHW transformer neither helps the antenna nor adds safety.

For storms: no arrestor or ground makes equipment strike-proof. The only certain protection is physical disconnection — unscrew the coax outside the house before a storm, and let the antenna take its chances. An arrestor at the properly bonded entry point protects against nearby-strike surges and static buildup, which is its real job.

One diagnostic note from our support experience: lightning arrestors contain gas discharge tubes that degrade or fail after surge events — often invisibly. A suddenly changed SWR after a storm season is far more often a failed arrestor than a damaged antenna or transformer. Bypass the arrestor and re-measure before suspecting anything else.

A Word on Codes and Safety

NEC-810 is a US code; other countries have equivalents (UK and European readers: see the RSGB’s grounding publication linked below). Local amendments vary, and lightning protection involves genuine life-safety and insurance implications — for the bonding work at your service entrance, involve a licensed electrician familiar with your local code. What I can tell you with authority is the RF side: what helps your station, what does nothing, and what makes things worse. The paragraphs above are that.

Frequently Asked Questions

Do I need a ground rod for my EFHW antenna?

No — not at the transformer, and not from the shack. Ground the coax shield where it enters the home per NEC-810, bonded to your electrical service ground. That is the whole requirement.

Is a ground wire from my radio to an outside rod a good idea?

No. At HF a long wire is an impedance, not a ground — it can radiate, it can present high impedance exactly where you wanted low, and it bypasses any choke installed at the radio. Handle grounding at the cable entrance instead.

Will a lightning arrestor protect my radio from a direct strike?

No device will. Arrestors handle induced surges and static; for direct-strike protection, physically disconnect the coax outside the house during storms. And remember arrestors fail silently — a post-storm SWR change is usually the arrestor’s gas discharge tube, not your antenna.

My tuner/manual says “connect to a good RF ground.” Do I need one?

For coax-fed antennas like ours, no — that advice dates from end-fed wires worked directly against ground from the shack. A properly built antenna system (transformer, coax, entrance grounding, choke if needed) leaves the shack with no RF job to do.

Does grounding affect my antenna’s tuning or SWR?

Proper NEC-810 entrance grounding does not change antenna tuning. If connecting or disconnecting a ground wire moves your SWR noticeably, that wire is carrying RF current — which means it’s acting as part of the antenna, and that’s a symptom of the problems described on this page, not a feature.

Watch: Dave Casler’s excellent video on station grounding bellow. For European installations, see the RSGB’s publication “Earthing and the Radio Amateur”.

Further reading: ARRL — Electrical Safety and Grounding · Antenna System Grounding Requirements (NEC 810) · K3LR — Grounding and Bonding for the Ham Station

Related: About Counterpoise · About CMC · All About EFHW Antennas · Shop CMC / RF Isolators

See the following links as well for supplementary info regarding any grounding and code/safety guidelines :