Station grounding and lightning protection that actually works

Grounding is the part of station building that gets treated as an optional upgrade and is in fact the only part that is a code requirement with a life-safety purpose. The National Electrical Code deals with it in Article 810, which exists because antennas on buildings burned houses down and killed people long before anyone was making DX contacts.

It is worth separating three different things that all get called grounding, because conflating them is how bad installations get built. There is safety grounding, which keeps fault current and lightning energy out of the house. There is RF grounding, which is about counterpoise and common-mode current and is a completely different problem. And there is the mains protective earth, which is the electrician’s domain and which everything else must be bonded to. This page is about the first, and it says where the other two connect.

The honest headline is that no grounding system makes a direct strike survivable for your equipment. What a good system does is keep the energy outside the building envelope, protect the structure and the people in it, and give the surge somewhere to go that is not through your operating position.

The single-point entry panel

Everything in a well-grounded station follows from one decision: every conductor coming from outside enters the building at the same physical place, through the same grounded plate. Coax, rotator cable, control lines and any DC feed from an outdoor supply, all through one panel.

The reason is potential difference. During a nearby strike the ground under your house rises to a large voltage for a few microseconds, and it does not rise uniformly. If your coax is bonded at one corner of the house and your mains earth is at another, the difference between them appears across whatever bridges them, which is your radio. Bring everything to one point and the whole assembly rises together, so there is nothing across the equipment.

What an arrester does and does not do

A coaxial arrester is a gas discharge tube, or on some designs a quarter-wave stub, sitting between centre conductor and shield. Below its firing voltage it is invisible to your signal. Above it, the gas ionises in nanoseconds and shorts the surge to the grounded body of the arrester, which is bolted to your entry panel.

• It protects the building and the people in it. That is its actual job, and it does it well.
• It clamps to a voltage, not to zero. A few hundred volts still get past, which is plenty to destroy a receiver front end. Arresters reduce equipment damage; they do not prevent it.
• It must be grounded to be anything at all. An arrester on a bracket that is not bonded to a real electrode is decoration.
• It is a consumable. Gas tubes degrade after firing. Replace them after a known nearby strike and inspect them every few seasons.
• It does not care which way the surge is travelling. Most damage arrives up the mains supply or across the ground rather than down the coax, which is why the whole-house picture matters more than the antenna one.

Grounding for RF is a different problem

Safety grounding stops fault and surge energy. It does almost nothing for the complaint most operators actually have, which is RF in the shack: a tingling microphone, an unhappy computer, an SWR reading that changes when you touch the case.

That is common-mode current riding on the outside of the coax braid, and the cure is a choke at the feedpoint rather than a longer wire to a rod. Adding ground wire to solve RF in the shack is a classic wasted afternoon, because at HF a ground wire of any practical length is an antenna in its own right. Read common mode current and RF in the shack for the actual fix, and use the balun and choke selection calculator to pick the right core and turn count.

The two systems do meet at the shack bus bar. Bond every chassis to a common bar, bond that bar to the entry panel, and let the choke handle the RF at the antenna where the current is.

What to do when a storm arrives

Every experienced operator with insured equipment does the same unglamorous thing, and it is the only measure that reliably saves radios.

1. Stop operating well before the storm is overhead. Strikes reach several miles ahead of the visible cell.
2. Disconnect every feedline at the shack end and physically move the connectors away from the equipment, ideally into a grounded box or out of the window. A connector lying next to the radio can flash over to it.
3. Unplug the mains supply to the station, and unplug network cables to any connected computer. Mains and Ethernet are the two most common entry routes for damage.
4. Leave the antenna side connected to the entry panel arresters. That path is doing its job.
5. Do not reconnect until the storm has passed the area entirely.

A grounding parts list

This is the complete set for a normal single-antenna house installation. Prices were researched at time of writing.

Everything the entry panel needs

Electrode, bar, bonding strap, arrester and the weatherproofing that keeps water out of the joint.

HEVIDUBANA

8 ft copper-bonded ground rod kit with clamp

A driven copper-bonded rod with a clamp. The electrode at the antenna end of the bonding path.

Check price$54.80

JMDECOUS

Copper grounding bus bar kit, 16 positions

The single point everything lands on. Buying the bar is what makes single-point entry happen rather than remaining an intention.

Check price$21.50

BuyUneed

Tinned copper ground strap braid, 15 ft

Flat braid has far lower inductance than round wire at surge frequencies, which is the whole game for a fast rise-time event.

Check price$22.99

Proxicast

Proxicast ProGrade coaxial lightning arrester, SO-239

A sensible gas discharge arrester for a 100 W HF or VHF feedline. One per coax run.

Check price$19.95

Not on Amazon

PolyPhaser

PolyPhaser IS-50NX coaxial protector

The reference-grade arrester, specified at commercial sites. Worth it when the station behind it is worth four figures.

Find comparable gear

Sold by PolyPhaser, through dealers, not Amazon. The link searches the category.

Maxwel

Self-amalgamating rubber splicing tape

Self-fusing tape for the outdoor connectors. Water in a connector defeats every other part of the system.

Check price$9.99

The full HF base station build prices this whole system as part of the build rather than as an afterthought, which is the right way to think about it: grounding is roughly five percent of a station budget and it protects the other ninety-five.