A few notes on grounding and lightning that are worth peaking at: “Florida 911 Center Upgrades Lightning Protection System for Maximum Safety” http://www.copper.org/applications/electrical/pq/casestudy/florida911.html <http://www.copper.org/applications/electrical/pq/casestudy/florida911.html>
"Proper Copper Grounding Systems Stops Lightning Damage at Nebraska FM Station" http://www.copper.org/applications/electrical/pq/casestudy/nebraska.html <http://www.copper.org/applications/electrical/pq/casestudy/nebraska.html> Sincerely, Joshaven Potter Google Hangouts: j...@g2wireless.co Cell & SMS: 1-517-607-9370 supp...@joshaven.com > On Dec 29, 2015, at 5:34 PM, ch...@wbmfg.com wrote: > > About lightening... there is stuff there but didn’t find the lightening > stuff. > > From: ch...@wbmfg.com <mailto:ch...@wbmfg.com> > Sent: Tuesday, December 29, 2015 3:33 PM > To: af@afmug.com <mailto:af@afmug.com> > Subject: Re: [AFMUG] WISP insurance > > Did not find anything at copper.org > > From: Joshaven Mailing Lists <mailto:lis...@joshaven.com> > Sent: Tuesday, December 29, 2015 12:18 PM > To: af@afmug.com <mailto:af@afmug.com> > Subject: Re: [AFMUG] WISP insurance > > Kinda off topic... Insurance of another type (avoidance) > > I often find locations where the grounds are hooked up to the tower ground > which includes one or more ground rods… but what often goes unrealized is > that the system is also grounded to another system through the utility > company… and the tower and the utility company may not be properly bonded. > So the lightning finds the big tower, and thinking it is a lightning rod… > uses some of the path to ground through rods at the base of the tower but > then also uses the path through the equipment to get to the power utility > ground…. and pop goes the radio and router and such… Just don’t be that guy > that connects the big lightening rod to the utility power ground through your > router... > > Your equipment should be surviving lightning strikes. Large towers can be > struck multiple times per month and equipment can be on them for years > without any damage at all. The fact that you lost equipment says that the > strike was either direct to your equipment or you have a grounding issue that > made your equipment a better path to ground. > > At some sites commercial radio engineers will even bring in a beaded cable > from the tower and spread it across the floor to set all equipment on just to > be sure that the ground panes are entirely bonded. The reason that equipment > blows is that the difference in positive to negative current is out of range. > When you get a lightning strike and things are not well bonded then you can > have variances between grounds in the order of thousands of volts which will > make your equipment pop like a fire cracker… if your ground is at 10,000v > (relative to an average earth voltage) and your equipment is at 10,024v then > the potential between them is 24v. It is like a bird setting on a high > voltage line… somehow they don’t “feel” the high voltage… The trick to > surviving a lightning strike is to bond all grounds well so ground is > constant and then to have your power level referenced from that ground. This > way if the earth ground or the tower ground or anything else has a sudden > change then your equipment changes with it and remains relatively the same. > After bonding your grounds properly so that you don’t end up with thousands > of volts difference between two grounds like your power company ground and > the tower that your equipment is mounted to… then you can install good surge > equipment that will handle current overages in the event that you need it. > > The thing to keep in mind when grounding your equipment is that you don’t > want your equipment to experience a situation like 0v for negative, 24v for > positive and 50,000v for ground. If your equipment ground plane floats with > a strike then it won’t even know that it experienced a surge. Just like a > boat going over shallower and deeper water — who knew unless they had a fish > finder running? > > During a strike, you don’t want a 5,000v on the utility ground while you have > a 25,000v on the tower… If the cable between the two (or patch of earth > between rods) won’t handle the surge or the impedance is too high then your > equipment will possibly have two grounds with two very different power levels > so the power will transfer from your shielded cable through your router > chassis to the utility power until a something pops. The bottom line make > the tower, earth, & utility power all the same and properly ground your > equipment to that and you’ll survive most strikes perfectly fine. > > if you want some good reading google the terms: “copper.org > <http://copper.org/> lightning” they have some great write-ups with pictures > of the good, bad and ugly. > > Sincerely, > Joshaven Potter > Google Hangouts: j...@g2wireless.co <mailto:j...@g2wireless.co> > Cell & SMS: 1-517-607-9370 > supp...@joshaven.com <mailto:supp...@joshaven.com> > > >> On Dec 27, 2015, at 10:31 PM, Craig House <cr...@totalhighspeed.net >> <mailto:cr...@totalhighspeed.net>> wrote: >> >> 2 in a year? We had 7 last night. >> >> Sent from my iPhone >> >> On Dec 27, 2015, at 21:22, Glen Waldrop <gwl...@cngwireless.net >> <mailto:gwl...@cngwireless.net>> wrote: >> >>> We’ve had another lightning strike, at least the second one this year. >>> >>> I’ve got this feeling that our insurance company is probably going to start >>> to get a little difficult in the near future. >>> >>> Who do you guys recommend? >>> >>> I’ve read about a few that cover everything, CPE, tower equipment, towers, >>> labor, etc... I imagine those probably cost roughly what we bring in a >>> year, but... >>> >>> Thanks guys. >>> >>> > >
