The grounding bus bars are isolated but I doubt the gear at the top is, the antennas and RRUs are bracketed to the tower…
From: Af <af-boun...@afmug.com<mailto:af-boun...@afmug.com>> on behalf of Paul McCall <pa...@pdmnet.net<mailto:pa...@pdmnet.net>> Reply-To: "af@afmug.com<mailto:af@afmug.com>" <af@afmug.com<mailto:af@afmug.com>> Date: Monday, July 24, 2017 at 2:29 PM To: "af@afmug.com<mailto:af@afmug.com>" <af@afmug.com<mailto:af@afmug.com>> Subject: Re: [AFMUG] Tower Top Grounding discussion Well, somehow this cellular guys survive these direct tower hits. Tower # 1 from the weekend is a 500’ tower that we are at 410 feet on. Two cellular providers right below us and a FM station and Lojack above us, and we were the only ones hit. Cellular guys have isolated ground bars at the top that are connected to the outside shield on their large coax cables, with a “wrap kit”. At the bottom of the tower, they have another isolated ground bar and attached the same kits to get the ground to the ground bar, then have their own grounds. MOST are doing it that way. I will send pictures of 2 different carriers on the same tower doing it differently. Tower #2, is a 130ft water tower with Verizon. They are at the top of the tower, have the same exact type setup. This picture is from a 3rd tower (bottom) that I took pictures … same thing. We do have fiber and 48vdc to the top and 48vd protectors (Polyphaser) at the top at both these towers. Everything blew, including the polyphaser that is grounded to the tower itself (on both towers). Obviously, that isn’t working :) From: Af [mailto:af-boun...@afmug.com] On Behalf Of ch...@wbmfg.com<mailto:ch...@wbmfg.com> Sent: Monday, July 24, 2017 1:42 PM To: af@afmug.com<mailto:af@afmug.com> Subject: Re: [AFMUG] Tower Top Grounding discussion Nothing stops a direct hit. It will blow up everything that gets in its way. You are probably seeing induced surges from nearby strikes. Fiber to the top. Surge suppressors on the DC conductors. Gino A. Villarini President Metro Office Park #18 Suite 304 Guaynabo, Puerto Rico 00968 [cid:aeronet-logo_310cfc3e-6691-4f69-bd49-b37b834b9238.png] From: Paul McCall Sent: Monday, July 24, 2017 11:20 AM To:af@afmug.com<mailto:af@afmug.com> Subject: [AFMUG] Tower Top Grounding discussion We have two 500ft towers that get hit a bunch, and a water tank that gets the same treatment from mother nature. Anybody doing full isolation of all their antennas, equipment etc. at the top of the tower and then running your own ground down the tower? 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 pa...@pdmnet.net<mailto:pa...@pdmnet.net> www.pdmnet.com<http://www.pdmnet.com> www.floridabroadband.com<http://www.floridabroadband.com>
