grounding rooftop discone

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With all these comments, I wonder how many looking for something solid to do about lightning are left dazzled ?


As PRC has pointed out, (and I agree)- if you are going to take this subject seriously, then there is a protocol to follow. If you don't, then there will be consequences. I guess that is what separates the Amateur from he professional. Even those of us in a position (and with a budget) to take this subject to perfection have to know we will not achieve 100% -
The gods love the hubristic- the narcissistic- and delight in unduing them accordingly.
Oedipus , anyone ?

I will go back to my original suggestion to COM19; As a radio guy with a modest little discone antenna, the probablity of any direct lightning strike is very! small. But don't hold me to that. So is the chance of being hit by a piece of Blue Ice falling from some airliner's leaking toilet tank- but that doesn't stop me from walking outside.

Major strike--> unlikely
Secondary spike that comes in over some 'line'---> what to fear


Read all you can about lightning- follow the experts advice as closely as your purse can allow- then get on with life. Keep in mind that lightning comes in all forms- from the tiny, little sparks that can be generate as "static electricity" - and will Zap! a solid state memory-- to the miles long streaks that will blast to smithereens a church's bell tower--
And extends to this, my favorite:

Ball Lightning

I wrote about this awhile back here in RR- but can't find that posting now. Oh well, down the memory hole-

I didn't see it personally, but I did see its effects afterwards.
It occurred at an ionospheric 'heating' transmitter site high in the Arctic.

Scene- its a dark, windless, moonless winter night; the Milky Way aflame with stars-- and- in the words of Robert Service- "the Northern Lights were running wild ....." Aurora Borealis supreme. :)

My friend and colleague had gone outside the living quarter's (a cosy ? Quonset hut) to check on one of the generators- leaving the rest of us ("its your turn to check on the monsters, Barb") with sitting around a glowing barrel stove, drinking a bottle of Jack Daniels.
She was hardly gone but a few minutes when she burst back in-

"Viens vite dehors! Ange Feu! " (Come outside quickly, its Angel Fire!")

"Angel Fire? what ?....No more for you Barbi"
"Cut her off !"

"No, really !- There is this white ball of.... what do you call it?.. Ball Lightning!.... its dancing on the -the (antenna) array!"

But by the time we were able to mobilize (not an easy thing to do on a night of minus 30F; going from sitting around a warm stove, and fortifed with adult beverage) -- by that time it was gone

"It was right up there, in the wires!- about a foot in diameter. It was a glowing white ball !... it floated about slowly, and landed at the base of that pole" (a tall telephone pole supporting a part of the huge curtain array.)

.............Okay, Barb.......... nothing to see here Guys

The next day I walked out to the base of that pole, and there, melted thru the snow and ice, ~3 feet down to bedrock- was a perfect one foot diameter hole.


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A conclusion?... you can draw your own- but lightning comes in all forms....the gods love to toy with us.

Lauri :sneaky:
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AK_SAR

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With all these comments, I wonder how many looking for something solid to do about lightning are left dazzled ?
Not to mention shocked and electrified? :)
Keep in mind that lightning comes in all forms- from the tiny, little sparks that can be generate as "static electricity" - and will Zap! a solid state memory-- to the miles long streaks that will blast to smithereens a church's bell tower--
Don't forget "Thundersnow".
A conclusion?... you can draw your own- but lightning comes in all forms....the gods love to toy with us.
Sometimes the god give us a little warning, just to see how we react.

One last (non-radio related) lightning anecdote. Back in the day, when I was younger and more agile, I used to do a bit of technical climbing. One time we were doing a climb on Mt. Washington in the Oregon Cascades (only about a 5.7, easy by today's standards but horribly loose). As we were doing the last pitch near the summit, we saw a thunderhead developing to the SW. Keep in mind, this is western Oregon, where thunderstorms are only an occasional occurrence (unlike Colorado where you can about set your watch by the afternoon thunderstorm). As we coiled the rope and scrambled the last few feet to the peak the storm was still some miles away. Suddenly our hair started standing on end, and I had the weirdest tingling sensation on my skin! We made the fastest descent on record , a bit of third class and a short rappel down the easy side, and ran, no flew, down the scree!

I've always though that Thor was laughing, just watching how fast he could make us move!
 
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Oh No !, more lightning stories AK :) - If one one else , I learn something about it from everyone's posts :)

It is such an anecdotal topic and filled with so much information if we take it on what occurred, real time- rather than quoting lofty text book figures and details.... at least for me.

Ah !... that pre-strike tingling !-- Been there-felt that!... from the hair on end to the ringing carabiner's rimmed with St. Elmo's fire !

I have often seen it dancing about on the peak of my Colorado home wood stove's flue. Everything there is "Floating Ground'd".. but when I see that, everything also gets unplug'd f-- everything. :)

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Lauri :sneaky:
 

jim202

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It must be some typos in the text as it makes no sense at all. Dirt isn't a low resistance material. You must have been measuring the resistance between the grounding cable and the mains ground, as you disconnected the wire to the ground rod, and then the placement of new ground rods are irrelevant to the low resistance measurements.

/Ubbe

In order to measure ground resistance, one generally uses a ground resistance test meter. It requires that you connect to the ground rod or ground system while it is disconnected from the utility power system. This is why you shut the power off and remove the ground wire from the ground rod that goes to the utility power system. The meter is a 3 point tester. It requires you to run out wires to two different test rods that are about 2 feet long. You then use the meter kind of like a test bridge that is using the original ground rod and the 2 other test rods that you have spaced out at specific distances. The ground resistance meter then provides you with what your "ground rod" effective earth resistance actually is.

It's not me that is writing the specs on grounding. There have been many years that have gone into how to ground telecommunications facilities. The original work was done by the Bell Labs many years back for their point to point microwave systems that connected the central offices around the country. This work was also picked up by the National Electrical Code (NEC) on just how grounding was to be done both in commercial locations and in residential homes.

It was also Bell labs that stopped using the tower foundation re bar as a UFFER ground to ground their microwave towers. They found out the hard way that the lightning was cracking the cement foundation and causing the towers to fail and hit the ground. So Bell Labs pulled away from using the UFFER type grounding system really fast. This is where the ground ring grounding system came from.

Somewhere along the way, Motorola jumped on the band wagon and developed their own standard. Part of what we know today as the R56 Standard contains a section devoted to tower, shelter, generator and power protection. It uses a single point ground bar system inside the equipment shelters and buildings. All the cable trays, equipment racks and any other metal inside the shelter like the air conditioning vents and metal door frames all get ground back to the master ground bar inside the shelter or building.

I am just pointing out the facts of these different grounding and surge protection methods that have been developed over the years by people much better in the know than any of us on the chat group here. I am also trying to bring out that there are a number of myths that have basically come from what many of us call wife's tales.

People can believe what they want, do what they want, but should be able to have someone point out that you don't have to spend a gold mine to protect your property. Some company specs require their vendors to follow what might just be way over kill.

I too have been on a bunch of mountain tops, but on the east coast. Yes there is a problem trying to obtain a good ground on top of a mountain where all you have is solid granite rock. But there are ways to be able to obtain a usable ground for your telecommunications site that is cost effective. You just have to work harder and spend addition funding to get it to work. Again Bell Labs has developed ways to make mountain tops have effective grounds. But I have never seen any 500 MCM size wire used to get that functional ground system to work. It all boils down to which engineers wrote the grounding specs.
 

samcken

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FWIW: Disclaimer, I have no electrical license and even less experience with moving electrons. So, a memory from decades ago:

My father's next door neighbor was a practicing New York architect and teaching professor at CUNY. I remember a discussion concerning grounding my dad's tv antenna (a device for grabbing tv signals, for you youngsters.) The professor explained that grounding wires would typically vaporize if they were hit by lightning, and that they were not intended to carry a lightning strike. Their purpose was to maintain a neutral zone (drawing the charge as needed from the ground rod) in the air above and around the house. This would make the lightning less likely to discharge in the area. True or false? Beats me, but that's how a tenured professor saw it!
 
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Hey Sam :)

If you were to ask me ? -- He was right.

Unless its a full blown, professional lightning suppression, the best anyone can hope for is exactly that- To bleed off a static charge.
Now that is no slouch of a purpose- the theory goes that if you dissipate the static charge you deflect the strike.
Around my western homes (I have one in Colorado and in New Mexico) we have these things that look like big fuzzy balls- kind'a of cheerleaders huge pom pom of stainless steel, on towers, that are placed about our electric company's transformer farms.

Again, the theory is that with these 'fuzzy balls' its their large surface areas that is going to bleed off a static charge---------------------

Does it work ?

Hmmmm .... I keep meaning to talk to the power company people about this, but in the mean time, I subscribe to their technology.
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At my home in Colorado (+9,000 ft. ) --- I have everything ground'd...
Of course this is all things antenna- but also its everything irrigation pump, mercury vapour lamp, horse stable-- the whatevers.... and most of all -- my woodstove flue.

My later is famous for its St. Elmo's fire--- it is not uncommon, on a really clear, still night- that the Angels will dance on my flue's cap.... Believe me, seeing that (!) will make a believer out of the "fuzzy ball" disapation theory.

That is why, anyone reading my comments should take comfort---- is that a good term?.. in that whatever you do, it is better than doing nothing. That run of #10 aluminum wire off the antenna mast to a puny 4' ground rod just might have bled off the "big one"--

So, let it strike the nearby water tower instead..... Heck, you will *Never Know* if it was worth it - but then again, you can then write some glowing Post about how a single piece of aluminum wire has saved your station year after year.

Yeah ;) !


But we know the truth :) --- It didn't deflect a direct strike-- it dissapated a static charge.


Zesus gave you a wave... but don't get too kocky**-- he hasn't forgotten you !




Lauri :sneaky:

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** the RR spell check'r didn't like this word with a "C"--- bummer
 
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prcguy

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Lightning is viewed as a rolling ball of charged stuff about 75 to 100ft in diameter like a giant beach ball rolling across the land and things that bump its mid section are more likely to generate a strike than something shorter or taller due to the curvature of the ball. There is a "cone of protection" theory based on this where towers around the 50 to 75ft height can protect shorter things around it at some calculated angle downward. It's actually recommended to put lightning protection air terminals or fuzzy ball dissipaters around 75ft elevation of a taller tower to force a strike there instead of at the antennas on top.

The cone of protection theory did not work out for my friend who was struck through a window in his basement. BTW, that was in Green Mountain Falls, CO, so beware L-C!



FWIW: Disclaimer, I have no electrical license and even less experience with moving electrons. So, a memory from decades ago:

My father's next door neighbor was a practicing New York architect and teaching professor at CUNY. I remember a discussion concerning grounding my dad's tv antenna (a device for grabbing tv signals, for you youngsters.) The professor explained that grounding wires would typically vaporize if they were hit by lightning, and that they were not intended to carry a lightning strike. Their purpose was to maintain a neutral zone (drawing the charge as needed from the ground rod) in the air above and around the house. This would make the lightning less likely to discharge in the area. True or false? Beats me, but that's how a tenured professor saw it!
FWIW: Disclaimer, I have no electrical license and even less experience with moving electrons. So, a memory from decades ago:

My father's next door neighbor was a practicing New York architect and teaching professor at CUNY. I remember a discussion concerning grounding my dad's tv antenna (a device for grabbing tv signals, for you youngsters.) The professor explained that grounding wires would typically vaporize if they were hit by lightning, and that they were not intended to carry a lightning strike. Their purpose was to maintain a neutral zone (drawing the charge as needed from the ground rod) in the air above and around the house. This would make the lightning less likely to discharge in the area. True or false? Beats me, but that's how a tenured professor saw it!
 
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Okay Guys, I just (re) watched this presentation by some engineers for IEEE.... what better way to spend time on a short commuter flight, No ?
(the passenger next to me ask'd "are you some sort of scientist ?!" --- like maybe I look like one who should be watching "The View"...?)

This is no lightweight video- but it deals with the Rolling Sphere lightning protection protocol- and other lightning tangentials, -- all in a very watchable, informative style. I saw it initially a few years ago and still recommend it highly today.

What is present'd is for electric substations- but if you can protect one of those, you can protect anything.

Kind'a on another tangent,---- this is the time the Navajo's call Ii’ni’ da’ałhosh - 'the season when Thunder sleeps."
Nice way to look at Lightning, and Winter.

Lauri :sneaky:

(Áłtsé hashké -- Coyote)
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(......Sorry, but you may have to back this up a little, it starts about 3 minutes into the video---)
 
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