When you take direct hits - there isn't much you can do but hope for the best. Good grounding will only prevent losses due to near hits and static discharges.
JohnnyO----- Original Message ----- From: "Michael Erskine (804) 436-9428" <[EMAIL PROTECTED]>
To: "WISPA General List" <wireless@wispa.org> Sent: Wednesday, May 23, 2007 11:02 AM Subject: Re: [WISPA] FM Radio and Ethernet
Mike Hammett wrote:Then why don't WISPs deploy a proper grounding system?Hmmm, Ok, I should have read the entire thread. Any WISP who does not deploy a proper grounding system is asking for it.We ground to copper "halos" that are attached to three eight foot copper clad rods. There are grounded surge supressors between each antenna and each radio and there are grounded surge supressors on each PoE line between the radio and the switch.The switch is grounded.So I can't say why someone else does not deploy a proper ground but I can say that we have not lost a radio in two years. I hasten to add that is not braggin' and please don't get me God, I didn't mean it to sound like anything but thanks.-m------ Mike Hammett Intelligent Computing Solutions http://www.ics-il.com----- Original Message ----- From: "Michael Erskine (804) 436-9428" <[EMAIL PROTECTED]>To: "WISPA General List" <wireless@wispa.org> Sent: Wednesday, May 23, 2007 10:24 AM Subject: Re: [WISPA] FM Radio and EthernetMike Hammett wrote:Why is it, then, that there aren't more radio\TV station outages due to lightning? They have to have done something to reduce their chances of a direct hit on those 1200' towers.A good grounding system that bypasses the communications systems.----- Mike Hammett Intelligent Computing Solutions http://www.ics-il.com ----- Original Message ----- From: "Scott Reed" <[EMAIL PROTECTED]> To: "WISPA General List" <wireless@wispa.org> Sent: Tuesday, May 22, 2007 8:32 PM Subject: Re: [WISPA] FM Radio and EthernetNothing stops direct hits. A spark that traveled through miles of air isn't really going to care what else is between it and the ground. Good ground is the lifesaver for nearby hits that induce wild voltages.And following the code is always best for the health and safety of the people.Jonathan Schmidt wrote:This has been my experience, Scott.I have seen lightening enter an enclosed device and simply burn a hole rightin the middle of a circuit board with nothing else damaged.On my desktop PC, lightening apparently came in through the cable, through the cable modem (destroyed) and down the Ethernet, through the Linksys (OK)to the PC and the only other damage was the motherboard Ethernet. Ireplaced the modem and bought a PCI Ethernet card and it's fine. What paths lightening took in this incident or the above incident is anyone's guess.There is still controversy over the value of diverting or directinglightening and/or lightening leaders and streamers to protect against adirect hit. It's really fascinating and here's a fun place to start you thinking: http://en.wikipedia.org/wiki/Lightning_rodNevertheless, good enclosures fed with metal conduit that's well groundedappear to do well but the local ordinances need to be heeded. . . . j o n a t h a n -----Original Message-----From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] OnBehalf Of Scott Reed Sent: Tuesday, May 22, 2007 5:35 PM To: [EMAIL PROTECTED]; WISPA General List Subject: Re: [WISPA] FM Radio and EthernetIf properly grounded, the opposite is true. The ground wire should direct the lightning to ground (hence the name) and away from your equipment.Not to mention that in the case of an equipment failure that causes the power supply to put 120VAC on the case, etc., the ground wire directs the current to ground, not you. It is always about safety. I would much rather have dead equipment than dead personnel because an electrical system was not properly grounded.Dennis Burgess wrote:YOU DO NOT WANT TO RUN A GROUND WIRE! The reason for that, is that then it gives lightning etc the ability to go though your equipment vs the towerground! B On 5/22/07, Scott Reed <[EMAIL PROTECTED]> wrote:Again,Check your local code before you copy this. No ground is not allowed here, unless somehow you can prove it is a temporary extension cord.Neither is low voltage in same conduit at 120VAC. That said, small changes to Dennis' configuration will make good installation. Run the cat5 in a separate (metallic) pipe (rigid, EMT, Sealtite,whatever you like). Ground the bottom of the pipe. I would leave thetop ungrounded, but that is: 1) personal preference (eliminates ground loops). 2) determined by which way gives you the best performance, least interference from the FM. You may want to use cat5e or cat6 as the twist is tighter, thus accepting less interference as well.Run a ground wire with the power. Even for the low current required at the top, I would probably run 14AWG or 12AWG. Lowers the inductance, may allow less noise to be induced on the power leads. Besides, 14AWG is the smallest wire you can run with a 15amp breaker. Same thing with ground loops; I would probably use a plastic box and thus isolate thepower ground from the enclosure, tower, etc. One good way to do it is consult a local commercial/industrialelectrician. They will know the code for your area. But they don'talways understand radio and induced voltages. Dennis Burgess wrote:We are located at 400 foot on a FM tower, 100,000 watts at the top of1400 foot.The total length of CAT 5 is 440 foot or so, and plug directly into aRB532 at the top of the tower (power at the top as well) We ran a felexable conduit up the tower, inside, 16awg solidcopper, oneblack, one white, (for the 110), NO GROUND, and also in that same conduit,we ran good outdoor, sheilded CAT5, UV Resistant (even though it isfullyenclosed), and we get a 100meg link without issues for the most part!One thing we did do, is ensure that we were on the other side ofall thetransmission lines running up the tower. DennisOn 5/22/07, Andrew Niemantsverdriet <[EMAIL PROTECTED]> wrote:I am co located on a tower with an FM transmitter. The FM stationrunsat 105Mhz. We were running one AP at 10 half duplex to overcome thehavoc that the FM station created on our ethernet feed. We nowneed torun that link at 100 full duplex to be able to handle the trafficcoming through it. What are some hints tips tricks to make it work.The cable run itself is 150' of shielded CAT5. It works fine at 10H/Dand it works at 100 F/D most of the time but it will occasionally go down and there is some intermittent packet loss on that link. The runitself terminates into a managed switch.If CAT5 won't work, is fiber my next option? How does that work? I assume that I need power up the tower as well? Any tips to make thathappen assuming keeping the existing CAT5 won't work. -- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/-- Scott Reed Owner NewWays Wireless Networking Network Design, Installation and Administration www.nwwnet.net -- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/-- Scott Reed Owner NewWays Wireless Networking Network Design, Installation and Administration www.nwwnet.net -- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/-- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/-- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
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