|To:||"Tom Rauch" <email@example.com>, <firstname.lastname@example.org>|
|Subject:||Re: [TowerTalk] Ground Radials Insulated or Not|
|From:||Jim Lux <email@example.com>|
|Date:||Mon, 06 Dec 2004 16:23:40 -0800|
At 07:00 PM 12/6/2004 -0500, Tom Rauch wrote:
> But is a good RF radial grounding system really "one of the best lightning > grounds you can get". A raft of small wires might well be a worse > lightning ground than a few nice big wires or rods. The smaller wires may > fuse with the lightning current. Say you get a 20kA strike and you've put > in 60 wires. That's 300+ amps into each wire (if the current divides > equally, which it probably won't). 300 Amps is a ballpark fusing current > for AWG10 wire in air (admittedly, that doesn't take into account the short > duration of the lightning impulse, etc.)
Do you also have a ground rod(s) or Ufer ground at the tower base? Or, are you depending on just the radial field for lightning protection?
I've always considered multiple radials to be a very good ground for lightning, and either that's correct or I've been very lucky for the 35 years I've had towers over 130 ft tall.
Could this be due to the rise in voltage at one end of the shield relative to the other? Was it an overcurrent failure or an overvoltage failure (i.e. melted metal or blasted through insulation?)
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA.
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