Hi Burt and all: Only a reminder: lightning is a pulse, and especially at the ground terminus can have frequency components in excess of tens of MHz. Think in terms of impedance rather than resistance. Many of the "freaky" things lightning pulses do are more clearly seen this way. A sharp bend in a ground lead, changes in wire size, spacing from other conductors, etc. etc. should be considered.
Use of "brush" or radioactive lightning rods, as has been pointed out, is pointless and even dangerous. If you feel you have to experiment with such, at least just use a sort of ball of barbed wire rather than paying someone a small fortune for junk. Any "brush discharge" lightning rod only serves to protect itself, and not even that in the presence of wind. Research points out :-) that rods of 1/2 or 3/4 inch, with hemispherical ends and well grounded with low impedance leads, are the right thing. The single plate ground point is of course correct, as is non-tapped leads from each piece of equipment. Don Latham www.lightningforensics.com Burt I. Weiner > Something I should've mentioned is that the connections are all > essentially in series. For example. If you have a wire going to a > ground rod and you connect several devices to it, they are all > meeting at the top of a "resistor". If a device attaches part way > down a wire or you have a wire running along the back of a bench and > the various pieces of equipment attach somewhere along he main ground > wire, this is like a tapped resistor. Each piece of equipment is > connected a some point along the resistor. > > Ground plates are usually insulated from walls, inside or out because > the wall can become part of the path. Lightning is tricky stuff and > the only rule it follows is that of finding the quickest and most > direct path to ground. However, that doesn't mean that it won't take > many paths. Make it convenient for it to follow the least damaging path. > > Again, > > Burt, K6OQK > > At 12:44 PM 10/4/2009, [email protected] wrote >>One of the ways that I've always explained this is to draw a >>schematic, actually more of a pictorial of the ground system and each >>piece of equipment in the overall system as a block. In place of the >>wires to ground, I draw a resistor symbol, including the ground and >>ground lead itself. In fact, each chassis or cabinet is also one of >>the resistors. By looking at it this way you can see that the ground >>system path is nothing more than a low resistance voltage divider, >>actually a current divider between a strike and the good earth. > > Burt I. Weiner Associates > Broadcast Technical Services > Glendale, California U.S.A. > [email protected] > K6OQK > > > > _______________________________________________ > 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. > -- Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com _______________________________________________ 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.
