ARROW Communications Association

March 30, 2007
Finally, the ice storms etc. seem to be over, but now the thunderstorms are appearing, turning my thoughts to lightning protection.

After reading, and reading, and reading, from everything from the Polyphaser documentation on the web to forum entries about the topic at eHam.net, I felt ready to get this part of the project started. I was also becoming very nervous about the increasing frequency of thunderstorm forecasts, and the fact that a few scattered storms had come near to my station over the past couple of weeks.

I decided I would put my lightning protection system outside the house, just inches from both my station cable entrance and the eight foot ground rod I put down outside the station last Fall. I also decided to go with Polyphasers, as few other brands of lightning arrestor are as prevalent.

After pricing Polyphasers at $81 each (list) and finding a web-seller discounting them to $51 each, I talked to a couple of local hams, one of whom recommended a scrap metal seller in town who would have a metal plate to mount the arrestors on. I thought I would mount the plate on standoffs from the siding of the house and use some scrap wood and left-over shingles to make a little "house" for the assembly which would keep the weather from sitting directly on the hardware. I hoped this would minimize corrosion problems.

Then, at the Maumee swap, I found a seller who had not only Polyphasers for only $25 each, but had a fully-fitted NEMA enclosure with a copper plate on insulating standoffs, pre-drilled for Polyphasers and ready to mount to the side of the house. He sold me a package of 4 Polyphasers and the NEMA box, ready to go, for $120!! What a deal!

So last weekend I mounted the box to the outside of the house with 1" lag screws. Then I noticed that the Polyphasers all had N connectors, but I was able to use N-to-UHF adapters I already had (and order a few more) to hook up my highest antenna first. I made a long jumper to run from the radio, out through the 4" PVC entry conduit, around a soft drink bottle about 15 times, and then into the NEMA box to connect to the arrestor. Note that the soft drink bottle-choke is intended to show the lightning impulse higher impedance leading into the house than the impedance to the ground rod.

I connected the copper plate in the NEMA box to the ground rod with about a foot of #6 copper, and pulled a piece of #6 copper through the basement ceilings, out through a convenient hole in the wall created for a cable TV line, and down the side of the house in a nice smooth (low impedance) curve right into the NEMA box. Then I connected other end of this ground wire to the ground wire going into the breaker panel for the house with two split bolt connections. That way when the lightning surge raises the ground voltage at the station side of the house, the connection the panel will minimize the voltage difference (and current flow) between the two. This is why you always bond all your grounds together - so the potential of the entire house wiring is pretty much equal, minimizing any voltage difference that would cause potentially damaging current flow. This is done at a single point to avoid resonant ground loops that could affect system noise levels, strange RF-in-the-shack phenomena, or even antenna characteristics.

I have another 8' ground rod, which I will undoubtedly add soon to improve the ground system, but at least I feel a good deal safer now, and am no longer worrying about coming home from work to find my $3500 Orion has exploded from a lightning strike, or that the house has burned down.

Of course, if there is a direct hit all bets are off, but in the face of the far-more-typical 100-1000 ampere surge from a nearby lightning strike, the system should shunt it safely to ground with no effect on my station or home appliances.