At a minimum, I would isolate your ground bar from the tower and run your own down conductor and then ground all your mounts and equipment to your ground bar. If that doesn't cut it you could try adding isolation between your mounts ant the tower but I doubt that is really needed.
On Tue, Jul 25, 2017 at 1:38 PM, Paul McCall <pa...@pdmnet.net> wrote: > Lewis, > > > > On option 2, if you are just leasing space on a tower such as Crown > Castle, etc., I have doubts that they would allow me to install the 8’ rod > at the top and run the 2/0 down the tower. So, would you, just do a 2/0 > starting at your equipment area, bond to the tower at that height, and go > down from there? > > > > On the “bonding everything together” scenario, if the tower ground is not > as good as the other grounds going down the tower (mine, the cellular > companies, etc.) won’t the differential in impedance cause the lightning to > 1) likely take the lesser impedance path down and/or 2) have the voltage > not rise and fall together and bad things happen from that? > > > > Paul > > *From:* Af [mailto:af-boun...@afmug.com] *On Behalf Of *Lewis Bergman > *Sent:* Monday, July 24, 2017 1:47 PM > *To:* af@afmug.com > *Subject:* Re: [AFMUG] Tower Top Grounding discussion > > > > On 1. it will be really difficult to completely isolate a piece of > equipment unless it is designed to float but good luck. If you are truly > going to isolate everything from ground then you won't need to worry about > #2 as all will float. You should check that the antenna you are using don't > require a ground plane. > > On 2. I Cadweld a 2/0 jacketed to an 8' rod at the top of the tower, not > isolated. I then bond (15 ton Hydraulic Crimp) it to a bus bar 5' below the > top for equipment grounds. Anywhere else there is a cluster of equipment I > also put a bus bar. I then take that 2/0 to the bottom to the last bus bar > and then into the ground ring. > > > > 1. *Wondering what materials people are using to isolate their mounts?* > What is sufficient? Would the rubber from a thick radiator hose be enough > to keep the lightning from coming through? Double thicknesses? > > > > One consultant recommended starboard, but I am not sure how I will craft > that into a work piece that would mold around a tower leg and be able to > grip it. > > > > 1. *What size wire should be going down the tower to bond to my tower > / electrical ground? * > > I am assuming it should be insulated but is normal THHN jacketing enough > to have it truly isolate from something jumping over or does it have be in > conduit. > > > > Paul > > > > Paul McCall, President > > PDMNet, Inc. / Florida Broadband, Inc. > > 658 Old Dixie Highway > > Vero Beach, FL 32962 > > 772-564-6800 <(772)%20564-6800> > > pa...@pdmnet.net > > www.pdmnet.com > > www.floridabroadband.com > > > > > > --
