Check out Erico website... they have an excellent PDF you can download. On Dec 29, 2015 9:28 PM, "Jaime Solorza" <[email protected]> wrote:
> When I wear my SCADA hat grounding takes a front seat. We take great > care to insure we follow sound methodology and take no short cuts. I have > shared many posts on how we do it... basically all of it hinges of Franklin > method. Those who know me, know I don't pull punches...if we were getting > hit allot I would post it. Yes we have had hits and lost equipment but it > is extremely rare. Consider that one SCADA network alone has over 500 > sites with elevated tanks, towers and masts all with yagis, sectored and > omni antennas with heliax cabling. Wisps around here get more hits. I > will share some links you might find useful. > On Dec 29, 2015 8:08 PM, "Faisal Imtiaz" <[email protected]> wrote: > >> I thought about commenting, walked away, but decided to comment at the >> risk of offending someone, but it would be worth it if the point being made >> and the information being shared was understood properly.. >> >> So here goes... Joshaven took the time and provided a farily accurate, >> detailed post on how to do grounding properly, and the potential issues >> when it is not proper. There is a lot of good information in there..... >> >> Glen I don't know if you realize what you did with your replies .... >> while sounding dismissive you actually have described the exact thing that >> Joshaven was trying to point out, as to what happens when grounding is not >> proper ! >> >> 'Grounding' is not just running some copper wires to be visually >> satisfying.... your statement about 'it is grounded pretty well...' >> followed by .. I have lost equipment there is an Oxymoron.... >> >> Grounding when done correctly will protect your equipment from having the >> type of damage you are describing.... and yes there are some ways to >> measure and determine if your grounding is proper ! >> >> >> BTW, Audio affects of a Lightning strike, shaking stuff etc etc is due >> to sound waves generated.. (sort of a mini explosion)... makes for great >> sound effect, but has nothing to do with electrical damage to equipment. >> >> :) >> >> >> >> Faisal Imtiaz >> Snappy Internet & Telecom >> 7266 SW 48 Street >> Miami, FL 33155 >> Tel: 305 663 5518 x 232 >> >> Help-desk: (305)663-5518 Option 2 or Email: [email protected] >> >> ------------------------------ >> >> *From: *"Glen Waldrop" <[email protected]> >> *To: *[email protected] >> *Sent: *Tuesday, December 29, 2015 6:02:24 PM >> *Subject: *Re: [AFMUG] WISP insurance >> >> Forgot to mention, this was one hell of a storm. >> >> Lightning from *several* miles away shook my home enough that the dishes >> rattled, the TV moved, cabinet doors opened and closed, etc, for upwards of >> 45 seconds. >> >> I’m honestly surprised we only lost one tower in that storm. I was >> preparing myself for putting up at least a couple of replacement towers >> over my Christmas break instead of goofing with the wife and kids. We got >> lucky and only lost some electronics. >> >> >> >> *From:* Glen Waldrop <[email protected]> >> *Sent:* Tuesday, December 29, 2015 4:57 PM >> *To:* [email protected] >> *Subject:* Re: [AFMUG] WISP insurance >> >> It is grounded pretty well, couple of ground rods, tower is grounded and >> the copper goes to the top, tallest point for quite a ways out there. The >> strike also blew out the neighboring transformer (didn’t hit my equipment >> directly). >> >> I have not been tying in my electrical ground with my tower ground. I do >> believe I’m about to change that. >> >> I do have a few other towers where the electrical ground is tied into the >> tower ground which is also tied to a copper wire (6 or 8, depending on what >> I had at the time) the entire length of the tower, bolted to the tower at >> the top and bottom. >> >> Those have also been struck. >> >> One of my most recent ones ran up the ethernet cable, fried the equipment >> at the top. POE on the ground survived, UPS survived and the surge >> suppressor (10/100M fusible link essentially) survived. The only radio to >> survive the strike was the only one I had forgotten to install a suppressor >> on. They were all replaced of course. The only equipment I’ve seen survive >> an actual lightning strike without a hiccup is the RB600. Everything else >> seems to die within 6 months. >> >> It appears the surge went through the ground (which we’ve gone over >> several times) into the surge suppressor, into the ethernet and blew out >> the radios. >> >> Any speculation on that would be awesome. The only thing that makes sense >> is that maybe the static was close enough to hit the electrical ground and >> go up the tower, but we’ve checked the ground rods and copper, bolts, etc. >> >> >> >> >> *From:* Joshaven Mailing Lists <[email protected]> >> *Sent:* Tuesday, December 29, 2015 1:18 PM >> *To:* [email protected] >> *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 lightning” >> they have some great write-ups with pictures of the good, bad and ugly. >> >> Sincerely, >> Joshaven Potter >> Google Hangouts: [email protected] >> Cell & SMS: 1-517-607-9370 >> [email protected] >> >> >> On Dec 27, 2015, at 10:31 PM, Craig House <[email protected]> >> wrote: >> >> 2 in a year? We had 7 last night. >> >> Sent from my iPhone >> >> On Dec 27, 2015, at 21:22, Glen Waldrop <[email protected]> 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. >> >> >> >> >> >>
