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Author Topic: Give your lightening strike story and what was your grounding like.  (Read 459 times)

W9IQ

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Re: Give your lightening strike story and what was your grounding like.
« Reply #15 on: April 17, 2021, 12:43:13 PM »

Now here is a thread worthy of locking.

- Glenn W9IQ

Only worthy cause of people like yourself needlessly.

That’s what happens when you think your IQ is higher, but only shows it’s not.


Very enlightening!

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

W6QW

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Re: Give your lightening strike story and what was your grounding like.
« Reply #16 on: April 17, 2021, 12:46:52 PM »

I once had stacked HF yagi's for 10M-20M at 90ft at a previous QTH in the SF bay area - a lot of metal in the air.  As California seldom gets lightning, I simply put two 6 ft ground rods at the tower base.  Well, there was one of those rare lightning events forecasted so I lowered the tower - the top antenna was still at 40 ft - well above surrounding structures.  I disconnected all the coax cables at the tower base and watched, in fascination, as the event unfolded.  To make a long story short, there was a lightning strike about 100 yards away.  Sure enough, I lost a clock radio - nothing else, but the local utility (the infamous PG&E) had to replace one of their pole-peg XFMR's at the point of the strike.  My guess is that the line surge was an induced voltage or I would have lost more electrical equipment.  I would have bet that the yagi's would have been the path of least resistance, as they say, but the lightning strike chose a different nearby path instead.

So, my tertiary contribution to your question is to also ensure that you AC mains are also protected as induced AC surges are more likely that direct tower or direct power line hits.

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N2RRA

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Re: Give your lightening strike story and what was your grounding like.
« Reply #17 on: April 17, 2021, 12:48:44 PM »

Here's a real story. My station in Las Vegas was hit twice by passive strikes of lightning. Took out the finals on my FT1000MP. Poor grounding at that QTH. Moved to Colorado where I have installed an excellent ground including lightning arrestors. Lots of lightning here and after 13 years here, no issues. Now, how can that be helpful to you?
Regards, Gary W0CKI, since 1954

It’s not a real story cause it doesn’t follow the criteria’s asked.

Only shows your story is full of cynicism, sarcasm and arrogance.

I could do this all day with a bunch of grumpy old men who have nothing to contribute whatsoever, but to antagonize and stir up trouble which is what you guys are doing right now. I’m not going to apologize for defending myself in an attempt to be verbally beaten up a bunch of old keyboard cowboy warriors. I’m also certainly not going to back down.

I don’t know how old you guys are, but other than acting like a bunch of high school childish low IQ imbeciles if you’re older than me I wish you were just 40 years younger. This is what hiding behind a radio and keyboard looks like all your lives, or for too long with out consequence.

I guess this is the future we gotta deal with. A bunch of geriatric operators that are trying to rekindle their 20 year old bad ass lives, or going through some middle age crisis. Maybe taking testosterone boosters or something? 🤦🏼‍♂️
« Last Edit: April 17, 2021, 12:59:43 PM by N2RRA »
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ND3C

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Re: Give your lightening strike story and what was your grounding like.
« Reply #18 on: April 17, 2021, 12:50:17 PM »

I've had two strikes. 

The first was to a tree which supported the apex of my inverted V. The hit did not appear to be to the antenna per se, but to the tree itself.  The coaxial feed to the antenna ran down the trunk of the tree where at the base of the tree, three 8' copper clad grounding rods, bonded together were connected to an Alpha-Delta gas discharge lightning arrestor, the feed line was trenched in a conduit to the foundation of the house where it was connected to a second Alpha-Delta arrestor connected to another cluster of grounding rods (about 5 or 6 as I recall) bonded to a ring of 000 gauge copper wire that encircled the house and was used to bond the cold water, landline, cable TV, power safety grounds, etc.  Several other ground rods from various utility entry points were bonded to this ring of ground conductor at the foundation of the house. 

I had a second strike at a different home a number of years later, same basic grounding configuration with a ring of grounding line encircling the house and multiple 8' ground rods.  In the second case, the strike was to a tall tree about 30' from the house, about 15-20' from an OCF 160 M dipole suspended from other trees on the lot.  The tree literally exploded from the strike with splintered wood blown out over at least a 50' radius surrounding the tree. This antenna, still in use, is fed with ladder line through a 4:1 balun at the entry point to the house at a 3rd floor window.  At the entry point, an Alpha-Delta arrestor is in in the coaxial line entering the house, grounded through 000 gauge copper cable to a similar ring of 000 copper encircling the house and bonding all other grounds.  In the case of the second strike, no direct damage was apparent to the antenna of feed.

When not in use, the incoming feed is grounded at an Alpha-Delta antenna switch, of note, also has a gas discharge tube as part of its design.

All my gear is connected to the AC line through good quality commercial grade surge protectors.

Long story short, I had only one radio casualty as a result of these two events.  My Flex 1500 was blown, not repairable at the second strike.  My other gear, multiple older tube type and more recent vintage radios including an ICOM 775 were not affected.

In both cases the network routers in my house, a digital TV, cable modem, and a couple desktop computers were destroyed. Several audio op amps were blown in the a stereo FM tuner which was protected with commercial lightning arrestor on the antenna feed, albeit probably not as robust as the heftier Alpha-Delta units on the Ham installation. 

The loss was clearly not the result of any direct strike or power line surge but from EMP effects of the very nearby hit and resulting huge E-field pulse produced by the lightning inducing current in poorly shielded consumer electronics.  I don't know of any way to prevent this short of building a Faraday cage enclosing the home.

The ARRL book on grounding and lightning protection is quite good and I highly recommend it.  Also, I've been very pleased with the Alpha-Delta hardware but I'm sure other good quality units would work similarly.  I just use what I know works.
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K8AC

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Re: Give your lightening strike story and what was your grounding like.
« Reply #19 on: April 17, 2021, 12:54:06 PM »

I have experienced two lightning strikes in my 62 years in amateur radio - both about 15 years ago and just two years apart.  In both cases, an 80 foot pine tree supporting my 160M inverted L, about 100 feet from the house, was hit.  Up until the first strike, I had paid little attention to effective grounding, probably thinking it couldn't happen to me.  After the first strike, I improved the grounding situation and so damages from the second strike were a fraction of that experienced in the first strike.  In both cases, the damage inflicted was due to failure to bond all the equipment cabinets to a common point, and, to adequately protect ALL wires entering the station room. 

In the first strike, most of the cabinets were tied to an aluminum bar mounted on the back of the table.  That bar was grounded via a #6 solid copper wire to a ground rod just outside the window.  It was an 8' copper clad steel rod and the wire was fastened to the rod with a compression clamp sold for the purpose.  This rod was NOT connected to the electrical service ground on the other side of the house.  I don't remember all the details of the damage now, but in general circuits that were connected to another piece of gear were damaged.  For example, the CAT port in the transceiver that was connected to the PC was damaged.  At that time, I didn't have the coax feedlines entering through a common grounded panel and one disconnected coax arced to a nearby PC cabinet - the burn mark was unmistakable.

After that, I installed an entry panel were all the feedlines went through lightning arrestors and that panel ground was connected to the electrical system ground, the tower ground and the ground rod outside the shack window.  Connections to ground rods were via compression clamps. All equipment cabinets were connected to the aluminum ground bus on the back of the table via #14 stranded wire.   A couple of years later, the same tree was hit again and this time the station damage was much less.  This time, the current through the ground from the strike must have induced quite a voltage in the underground telephone line and I had not thought of installing any protective device in the phone line.  In those days, we were using dial-up internet access with the phone line connected to the PC modem card.  The phone wires were blasted off of the phone company box on the outside wall and the PC modem was toast, but there was little other damage. 

I had Polyphaser lightning arrestors on the coax lines, TV coax, rotator lines and other switching relay lines in my outdoor common ground panel.  Those apparently did the job for the second strike.  A Panamax surge protector on the TV and stereo system AC lines was destroyed, but none of the attached devices were damaged.  I think that we spend too much time worrying about how to handle a direct tower strike and too little time on the most likely cause of damage - high voltage differences between equipment chassis and between ground rods.  If you don't tie the ground rod just outside the shack to the electrical panel ground rod, with thousands of amps of strike current flowing through the ground there will be a substantial difference in potential between the ground rods.  Your AC powered equipment will be at the potential of the power system ground in some circuits and the chassis ground connected to the ground rod might be at a potential of thousands of volts higher.  That difference will be resolved when internal arcing destroys circuit boards, etc.   I think it's of utmost importance to tie all the ground rods together AND to make sure all the equipment cabinets are also tied to a common ground bus in the station. 

If you're building a new house, W8JI has a lot of good info on the right way to do lightning protection.  Unfortunately, we usually have to compromise quite a bit when trying to install proper protection in an existing structure.  Here's something else I learned in dealing with the insurance company on my first lightning hit: They were willing to pay me $25 per hour to fix many of the lesser problems myself rather than sending gear off for repair or replacing it with new. 

73, K8AC


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N2RRA

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Re: Give your lightening strike story and what was your grounding like.
« Reply #20 on: April 17, 2021, 01:09:54 PM »

I once had stacked HF yagi's for 10M-20M at 90ft at a previous QTH in the SF bay area - a lot of metal in the air.  As California seldom gets lightning, I simply put two 6 ft ground rods at the tower base.  Well, there was one of those rare lightning events forecasted so I lowered the tower - the top antenna was still at 40 ft - well above surrounding structures.  I disconnected all the coax cables at the tower base and watched, in fascination, as the event unfolded.  To make a long story short, there was a lightning strike about 100 yards away.  Sure enough, I lost a clock radio - nothing else, but the local utility (the infamous PG&E) had to replace one of their pole-peg XFMR's at the point of the strike.  My guess is that the line surge was an induced voltage or I would have lost more electrical equipment.  I would have bet that the yagi's would have been the path of least resistance, as they say, but the lightning strike chose a different nearby path instead.

So, my tertiary contribution to your question is to also ensure that you AC mains are also protected as induced AC surges are more likely that direct tower or direct power line hits.

Interesting and great input. Most operators aren’t gonna think to much into their A/C lines. No matter what they may hear mentioned, or even read one time, or another their going to always concentrate on antenna and station grounds, but then quickly forget about their A/C panel. There’s always a possibility that over the years as a home gets older and new residents move into the house they may have service upgraded by a contractor, but many homeowners do the work themselves sometimes overlook their grounds to cold water main. Perhaps the installation was done by the wrong people installing the upgrade so always good to double check is the point and do what must be done.

So as much planing and concentration goes into antenna grounds now it’s a reminder and more imperative to now concentrate in my A/C panel and lines.

Thank you for your contribution sir.

73
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