Grounding and lightning protection is not a simple subject Phil. Here's what I would recommend:
If your home is wired to NEC standards, the neutral [center-tap on the pole pig] will be tied to the safety ground [green wire in your outlets] and earth at the service entrance ... only. This means that the "green wire" in each outlet snakes back to the service entrance before encountering a "real" ground. It thus makes a useless RF ground and lightning is RF [see below]. A. You *must* tie your ground rod back to the ground at the entrance panel. NEC requires it and if it isn't so tied, it can create a real safety hazard if you should encounter a ground fault. Make it as short as possible, buried is best, but if short means run under the house, that's OK. Use #14 copper or larger. B. AC is excluded from the inside of a conductor by the magnetic field it creates, and flows near the surface [skin] effect]. The higher the frequency, the closer to the surface it is. The conductors on one of the original 230 KV lines from Hoover Dam to Los Angeles are hollow for that reason. C. Lightning currents are mainly RF, and flow only on the very surface of the conductor and you want a lot of surface area, volume contributes almost nothing. So, wide copper strap is good. Large gauge stranded copper wire is less effective but better than solid wire. For the fire lookouts on peaks here in the Sierra Nevada, they use 3/8" - 1/2" stranded wire running around the roof, catwalks, and tower legs, bonded to everything including an extensive ground system. D. Surviving a direct hit to your tower or antenna is problematical at best. Even if you disconnect and ground your antenna [and rotator] cables, the induced currents will create high peak potentials to your equipment [and everything else in the house]. You can't stop that from happening, and your radio chassis can momentarily rise to very high potentials.The grounding goal for your equipment is to "keep it all together." The radio chassis can experience a peak pulse, but if everything else also gets that same pulse, the differential potential between them is very low, and little current will flow. The way you do this is to bring your ground strap into the shack, and using the shortest wiring you can, ground *each* piece of equipment *separately* to the same point on the strap. E. A grounded entrance panel for your coax and rotator cables is very good, use Polyphasers or similar to bring the cables through. They won't survive a direct hit, but in that case, that's the least of your worries, your house may be on fire by then. :-( They will clamp off induced pulses however and limit potential excursions on your equipment. F. Unless your home is on stilts over salt water [unlikely in NM :-) ] I'd guess that your ground rod is probably pretty high impedance for any currents generated by lightning. At the TV station I worked at in college [500' tower on a 1,300' ridge], the ground system ran all around the building with a bunch of ground rods, and included things like the tower, the fridge, plumbing, the 3 1/8" hard-line exterior, even the gate on the road, and the steel trench covers inside, They still made a deafening "clang" when we took a nearby strike. Hams do install systems like that around their houses, it's expensive and it's really a trade off with risk. G. If you have an Elecraft rig, you're covered. If you don't, make sure there's a bleed [RF choke or high value resistor] across the antenna connector. Precip static can sound innocuous if annoying, but without the bleed, it can store charge in the input circuit and ultimately cream it. We killed 2 IC-756PRO II's in 2009 from this in a snowstorm during the Cal QSO Party in Alpine County. If you have any specific questions, I'd recommend first contacting Jim, K9YC [who is really near Santa Cruz CA]. He has a wealth of information and tutorials on his web site. The grandson of Art, my Elmer of 57 years ago, W6RMK, now holds his grandad's call and has made his living as a lightning expert. If some question comes up, I'll be glad to take it to him. This pretty much exhausts my knowledge. 73, Fred K6DGW Auburn CA On 3/28/2011 9:35 PM, Phil Townsend wrote: > Lightning question: > > I have driven an 8 foot copper clad rod just out side my operating station. > Its about 6 feet from the rod to my desk. > I have attached a solid copper wire (1/4" thick) to the ground post (with a > ground rod clamp) The wire goes thru the wall and is bonded to a copper pipe > that is 1-1/8" wide that is just under the desk. > > So on to my question: > What is the BEST way to connect my equipment (k3, SB-200 and a remote coax > switch) to the copper pipe? > > Coax braid from RG8 or solid copper wire? and why.... > > > Thank You guys... > > Phil > Santa Fe > > soon to be a xx5SSR... > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > > > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Version: 10.0.1204 / Virus Database: 1498/3535 - Release Date: 03/28/11 > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
