A particular thread on one of these lists spoke of ways to disconnect coax, rotator control lines, etc. at or near where they come into the building. One implementation described by some fellow used relays to disconnect things so he could through one switch and instantly isolate his radios from the antennas.

The problem with this is obvious as the gap between the open contacts of a relay are easily breached by the enormous energies associated with lightning events.

The reason why can be understood with the following value of the breakdown potential of a air gap…

Translate this to, say, a 1 mm gap between the open relay contacts results in only 3,000 volts before breakdown begins.

3,000 volts sounds like a lot, but to a lightning surge it really amounts to nothing. Remember lightning travels far more than that small gap to get to ground and won’t have any problem making the final jump.

So, really, the best approach to disconnecting your equipment remains detaching coaxial cables and ensuring they are far away from the connectors.

Of course designing in good lightning protection devices on a good single point ground (SPG) is still urgently suggested.

You spent good money on your Icom, Kenwood, Yaesu, Ten-Tec, Elecraft radio… probably a lot. No ham shack is complete without spending, say, another 10% of the radio cost on lightning protection from PolyPhaser, Alpha, etc.

Consider good lightning protection cheap insurance for your radio investment. Don’t be cheap.

Last night on our Sunday Night Tech Net (Fauquier County, VA Repeater) a fellow named Bob brought up the topic of proper grounding for his upcoming coax fed 40 meter antenna. During the discussion about common ground points and other relating lightning protection possibilities, he recalled a story.

Seems , once upon a time, Bob installed some 120 Vac yard lighting around his property. The lighting worked quite well, but Bob immediately correlated a rise in damage to devices plugged into the ac power in his house with the installation of this yard lighting.

It would seem Bob inadvertently created a large antenna system which more efficiently coupled energy from lightning storms to his house wiring. Bob mentioned devices as simple as hair dryers were made useless by the surge energy.

The solution for Bob was to install good shunt protectors on his electrical distribution panel to quench the over voltage induced by lightning storms on his yard light wiring. Bob used MOV style protection.

The Polyphaser IS-PM240-xx is one option…

For less protection and less money the Polyphaser PSP-240 may help…

Small 240 Mains Surge Protector

This year Virginia has been hit with many thunderstorms so lightning protection is a popular topic for ham radio folks as well as folks who are simply trying to beautify their yard with lighting. If you are considering extending the wiring in your home you are well advised to add protection like Bob did to protect your loved ones from the much larger antenna you have made. You might also consider low voltage lights and/or an isolation transformer between your house and outside lights. There may even be a NEC requirement for this, but I am not sure.

When in doubt, seek out the advice from a competent licensed electrician.

There is also a rumor warranties on big ticket items like washing machines, dryers, heat pumps, etc. do not cover damage caused by surges since you are “expected” to provide this protection for your house. When you look at things this way, the few hundred dollars spent on a good panel mounted surge protector is a real steal.