FWIW, when grounding the metal mast of a boat, three inch wide copper strap is used because it is a better RF conductor. The strap is available in marine supply stores.
You really don't want lightning punching one or more holes in your boat, so whatever hits the mast (usually the full stroke, not a side shoot) gets directed directly to the keel. IIRC, gas discharge tubes take some time to ignite, so something faster is required to take the initial current. Bill Hawkins -----Original Message----- From: time-nuts [mailto:[email protected]] On Behalf Of Dave M Sent: Saturday, October 18, 2014 12:48 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Lightning arrestors for GPSDO antenna Chris Albertson wrote: > On Thu, Oct 16, 2014 at 7:51 PM, Dave M <[email protected]> > wrote: > >> Thanks, Chris. >> I've done a bit or research on the subject, and think I have a >> reasonable grip on the necessary steps. I have an 8' ground rod >> driven into the ground directly under the spot where my antennas >> mount. #6 solid copper from the rod to a heavy aluminum plate, where >> the arrestors will be mounted. A #6 solid copper wire from the plate >> to the antenna mounting structure. > > > About the only thing you left out is the interconnection between this > new ground rod and the existing house ground. > > Sounds like you must live in Florida. The best source of information > is the lightening lab at University of FL. > > I've never read a good research backed paper on plastic v. metal > conduit. I bet it does matter. I use iron pipe outdoors then after it > gets indoors switch to plastic. Practical reasons. The flexible > plastic conduit is just easier to use Actually, I lived in Florida for about 40 years, retiring to north Alabama about 5 years ago. about 6 of those years were spent working at a Motorola 2-way radio shop. So, yes, I'm pretty familiar with the damages that lightning can cause, and some of the precautions that help minimize susceptability and damage. As I posted earlier, I've seen writings promoting metallic and non-metallic conduit for the antenna coax. I can see reasons for placing the coax in metallic conduit. But, one thing that I've read that is consistent, is NOT to run the earth ground wire in metallic conduit. That's to keep the current to ground in a solid, unbroken path, which the fittings used to join conduit can't provide. OK to run it in non-metallic conduit to keep it out of the weather. Since my coax run is only about 20 ft, I'm thinking that I should be OK with the coax in 1/2" galvanized steel conduit. I agree that the metallic conduit should stay outside, and not be connected to the equipment ground inside. I'll run a separate ground wire from the equipment rack to the ground rod outside. Cheers, Dave M _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
