| [Tech Ops] Grounding question for the experienced members Hi guys, one thing I'm really nervous about being so new to the WISP game is lightning. I'm in NE Oklahoma, and spring storms are always very active.
I've read so much about grounding here - it seems as though everyone can tell me a different opinion.
I know it's unrealistic to think that I can safeguard against lightning 100% of the time, but what can I do specifically to reduce the odds of frying gear?
What is the best way to ground the following setup?
Roof top non-penetrating mount made up of an aluminum tripod, mast is aluminum sections, sitting on a homebuilt wooden base.
The antenna is a 24 dbi grid, the board is an rb411 with an XR2 radio. I believe the radio card has it's own ground line. The rb and radio will be in this weatherproof enclosure: »www.wlanparts.com/product/ODE-MT···MTK.html
Possibly a very short run (1 meter or less) of LMR400 between the enclosure and grid.
Sorry for the excruciating detail, wanted to give you guys as much to work with as possible.
Thanks in advance for the benefit of your experience. |
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1 edit | Copper-clad steel grounding rod that extends several feet above the antenna bolted with U-bolts to the aluminum mast, and #10 gauge wire clamped with copper nut down to the electrical utility ground.
Edited to mention..Use stainless steel washers between the copper rod and aluminum mast
Or #10 copper wire bolted to the aluminum mast with stainless steel bolts, nuts, and washers. Don't let the copper come in contact with the aluminum directly. Use some anti-oxidant past on everything. Tape and seal with mastic. |
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1 edit | said by nevtxjustin:Copper-clad steel grounding rod that extends several feet above the antenna bolted with U-bolts to the aluminum mast, and #10 gauge wire clamped with copper nut down to the electrical utility ground. Or #10 copper wire bolted to the aluminum mast with stainless steel bolts, nuts, and washers. Don't let the copper come in contact with the aluminum directly. Use some anti-oxidant past on everything. Tape and seal with mastic. Should I be tying in the ground line from the XR2 radio card to this line as well?
Edited for manners: Thanks for your reply! |
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 John GaltForward, MarchPremium
join:2004-09-30
Happy Camp
kudos:3 | reply to jim_p_price7
»www.polyphaser.com/technical_notes.htm
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Remember, Tuesday is Soylent Green Day.
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| Thanks for the link! |
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John GaltForward, MarchPremium
join:2004-09-30
Happy Camp
kudos:3 | Sure!
It is better to know -why- you are doing something rather than simply -how-.
To that end, here are a few more:
»www.solacity.com/Lightning.htm
»ebiznet.sbc.com/sbcnebs/Document···6403.pdf
»www.harger.com/harger.html
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Remember, Tuesday is Soylent Green Day.
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| Awesome! I appreciate you sharing some resources. |
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| reply to jim_p_price7
or leave it floating like I have done for two years with that identical setup and have never had problems.
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| said by thewisperer:or leave it floating like I have done for two years with that identical setup and have never had problems. Floating? As in, not grounded? |
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| I have had sites in the past that were completely ungrounded and sites that were well grounded. Sites with proper grounding lost far more equipment than sites that were not. |
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Diddy1
join:2003-07-19
Sidney, NE
2 edits | said by battleop: Sites with proper grounding lost far more equipment than sites that were not. This is curious. No sarcasm intended. Were all the "proper grounded" sites bonded back to , or grounded to main building ground? And were there no tight bends in the ground wire? I ask only for educational reasons like the OP. Also IMHO, grounding is not only, or guaranteed, to save equipment. But, to prevent damage or potentially dangerous conditions to the building or occupants as well. A direct strike to a device itself will not survive under any type og grounding setup in my experience.
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if you fail to plan, you plan to fail |
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| Yes, these were colo's at Cell sites. The other improperly grounded sties were telephone poles on the edge of a mountain or a HAM Operator's tower. |
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| reply to Diddy1
said by Diddy1:said by battleop: Sites with proper grounding lost far more equipment than sites that were not. This is curious. No sarcasm intended. Were all the "proper grounded" sites bonded back to , or grounded to main building ground? And were there no tight bends in the ground wire? I ask only for educational reasons like the OP. Also IMHO, grounding is not only, or guaranteed, to save equipment. But, to prevent damage or potentially dangerous conditions to the building or occupants as well. A direct strike to a device itself will not survive under any type og grounding setup in my experience. And that's one of my main concerns - as a rooftop leasee I do not want to be the guy that didn't ground his gear. That makes me an easy target for fingerpointing, whether or not my lack of grounding attributed to damage or not. |
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| said by jim_p_price7:And that's one of my main concerns - as a rooftop leasee I do not want to be the guy that didn't ground his gear. That makes me an easy target for fingerpointing, whether or not my lack of grounding attributed to damage or not. Which is a very valid point. If you follow best practices AND adhere to the NEC recommendations (or rules if codified into the local building code), then they can point fingers all they want. |
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| reply to battleop
said by battleop:Yes, these were colo's at Cell sites. The other improperly grounded sties were telephone poles on the edge of a mountain or a HAM Operator's tower. Cellular and public safety sites take direct hits all the time and don't have damage. Something doesn't makes sense, so that means we're not getting the whole picture.
At the colo sites, what was damaged? Amateurishly installed radios?
On the telephone poles, what would "improperly" grounded mean? Did they not have a #10 or #6 copper ground wire attached to a copper plate nailed on the bottom end of the pole in the ground? |
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| At the Colo sites, most often the antenna from a direct strike, which were not the highest thing on the tower.
When I say improperly grounded at the Telephone poles, that's as in no ground what-so-ever.
We didn't lose a lot of gear, maybe 10 things over 5 years across 8 sites. It's was just 9 out of the 10 devices were at cell sites. |
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John GaltForward, MarchPremium
join:2004-09-30
Happy Camp
kudos:3 | reply to jim_p_price7
It is necessary to understand that there is a vast difference between the requirements of the NEC and the "comprehensive and exacting requirements" for an -effective- RF and lightning protection grounding system that limits equipment damage.
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Remember, Tuesday is Soylent Green Day.
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| reply to battleop
said by battleop:I have had sites in the past that were completely ungrounded and sites that were well grounded. Sites with proper grounding lost far more equipment than sites that were not. I hear ya there.
I can pay no attention to grounding and it wont get damaged.
I pay attention to grounding and it blows up.
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OptionsDSL Wireless Internet
»www.optionsdsl.ca |
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| reply to John Galt
said by John Galt:It is necessary to understand that there is a vast difference between the requirements of the NEC and the "comprehensive and exacting requirements" for an -effective- RF and lightning protection grounding system that limits equipment damage. This is the truth!
Those guys saying they are grounding their stuff, are not doing it correctly. You must follow each detail of a comprehensive grounding plan for radio communications sites. There are documents produced by the US Military (MIL-HDBK-419A), documents by Motorola (Motorola R56), documents by the various carriers, etc that all mirror each other in one way or another. Follow these documents and the chances of you loosing equipment go down exponentially, if not completely.
Failure to follow each detail, will result in your experience of "I grounded the hell out of the site, and I STILL lost gear.".
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"No job is so important, and no service is so urgent that we cannot take the time to perform our work safely."
-- AT&T, Your World, Destroyed.
--Safety One Tower Rescue Certified
--LLigetfa:"Wimax is like teenage sex. Everyone talks about doing it." |
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 SplitpairPremium
join:2000-07-29
Cow Towne
kudos:3 | reply to battleop
said by battleop:Sites with proper grounding lost far more equipment than sites that were not. And I am quite willing to bet in reality the grounding at those sites was not so proper.
An installation which has is properly engineered grounding and bonding can withstand even direct hits without the loss of equipment, period end of story.
Wayne
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If you cannot fix it with a buttset and some beanies you're not a technician. |
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