a big part of lightning protection is also CHARGE DISSIPATION. That is the ONLY advantage of the #12 wire i mentioned. (when compared to other possibilities)
resistance, (.00187ohm/ft)
ohms per foot of wire is almost neglegable when we're looking at lightning. Sure, the DC resistance ADDS to the inductance of other wire, but you really can't compare just the DC resistance.
the DC resistance of 50' of #12 wire probably isn't all that different from 50' of 3" wide flat copper strap, but guess what? the copper strap is the BETTER (not best, mind you - the best would be unattainable by even some of the richest people we can all think of, given the price of metals nowadays!) as lightning protection for a near or direct strike because it has lower INDUCTANCE per foot, which even more greatly reduces it's "ac resistance" (reactance or IMPEDANCE).
also consider that my little #12 wire runs directly to ground. The coax runs into the house, to the radio, down the 3rd wire, to the AC service panel, THEN to the ground system, which may be all the way across the house. If done PROPERLY, the direct-to-ground wire should be SHORTER, and even neglecting complex impedance, should have less DC resistance to ground.
There are also huge problems caused by just grounding the antenna and not properly bonding the entire building to the same ground.
agreed...never said otherwise, i don't think.
I'm just pointing out some often overlooked problems and how complicated the subject is to give absolute answers on a scanner forum.
correct, this could be an entirely dedicated forum for that subject, and it STILL woudl never be completely covered. it's a big topic, and there are TOO MANY MISNOMERS out there - my biggest pet peeve are the poeple who drive a second ground rod for their station, and never bond it to the building ground.
Is there anyone here that is trained in designing lightning protection that will assume all liability in the event someone’s equipment or house is destroyed from bad design or advise? If not, the best advise is to get proper advise from an expert.
I think the biggest problem many people have is where they can find an expert. Any forum has the "This has always worked for me" guy who has installed something so unsafe, his insurance company cringes everytime a drop of rain hits the ground near his place.
I work in a facility that has been designed to survive direct lightning hits to protect the hundred and something million dollars of equipment inside and I see what is required to get there. I also have mountain top repeater sites that were designed from the ground up for lightning and have taken direct hits over the years (as evidenced by exploded and burnt fiberglass antennas on the ground) and no damage has ever occurred to the equipment inside.
I'm an EMI engineer who works quite closely with projects trying to design their equipment to handle the effects of indirect effects (see DO-160's requirements - some lightning transients are on the order of several kV and several thousand amps!) - I may not be an expert, but i don't want to see someone put something in (such as a ground rod separate from the buildign ground) that may create more problems than they're worth.
(Like i said, i'm interested in discussing - I like a little debate on occasion!)