Lightning Strike  - Page 1
Forum section: electronics / general

author: joeqsmith
author_rank: Super Contributor
timestamp: April 09, 2022, 06:19:42 pm
content: A few years ago some of my test equipment was damaged after one of our trees took a direct hit and it traveled down the tree into the roots where it coupled onto some of the wiring. We had another tree that it blew the bark off from one branch to the bottom of the trunk. We cut one of them down and it appears the center of one of the branches was carrying some current... Mother nature does a much better job than my transient generator.

author: cdev
author_rank: Super Contributor
timestamp: April 09, 2022, 06:23:21 pm
content: I've had that too. Twice.. I wonder if that carbonized stripe in the trees conducts electricity more, or God forbid, attracts more lightning.Just yesterday we had a big lightning storm which went right over us. It was quite dramatic.I wish that I knew more about lightning protection. In comparison to California, big lightning storms are much more frequent here in New Jersey. Strangely, there were few in the SF Bay Area, although they did happen occasionally.I have consumer grade (Belkin) surge suppressors on my computer stuff and (almost never used) TV.

author: TimFox
author_rank: Super Contributor
timestamp: April 09, 2022, 06:40:43 pm
content: Was there any pattern to the damage to your electronic equipment from that strike? (I.e., mainly in line-connected power supplies, or sensitive electrical inputs that were connected elsewhere, etc.?)

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 09, 2022, 06:44:08 pm
content: Yeh, at those currents, doesn't really even matter where the current path is!Parents had an instance a couple years ago, struck a neighbor's tree I think? Knocked out a couple devices including, what was it, a cable box and a router or two, something like that. Reasonable enough; CATV and networking cables make pretty big loops against each other, or to mains wiring, in many installations. (Which, it's an old house, wiring is everywhere.)Shouldn't have any effect on strike frequency, anyway; the moist tissue keeps the whole tree very nearly at ground potential, allowing the same electric field as a many-leafed lightning rod might.Not that that's helping put your mind at ease...Tim

author: joeqsmith
author_rank: Super Contributor
timestamp: April 09, 2022, 07:30:56 pm
content: There is a phone line, cable TV coax, AC mains and 24V sprinkler wiring underground. The sprinkler system was not plugged in but of vaporized the spark gaps and some other parts of the PCB. We have not used the copper phone lines for many years. There is a metal box that covers the junction where they feed into the house. That box was in my neighbor's yard several feet away. The coax took out my cable modem. The test equipment was all turned off and the bus strips were all off. My office has two outlets and they use the two different phases. There was enough common mode voltage between the two grounds that it took out the GPIB controllers. Nothing too bad. I made a video showing the repairs.

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: April 14, 2022, 12:46:18 pm
content: Tremendous energy in lightning - some years ago a neighbour had a very large tree struck. It had a diameter of about 3m and split into two trunks quite low down. The bark blew off and spread over 60m away. The tree had to be felled a few years later. It was interesting to see the cell damage in the trunk that was hit - there were thousands of radial cracks between the rings. The timber was of no use apart from firewood as it had no strength. The other trunk sold for $20,000 after it was slabbed.

author: coppercone2
author_rank: Super Contributor
timestamp: April 15, 2022, 06:28:54 pm
content: I highly recommend making a epoxy table top from lighting struck tree to cover your repair costs. You put the trees in a mold to make a pretty pattern, pour epoxy on it and put it in a big rented planer to make something really expensive.

author: cdev
author_rank: Super Contributor
timestamp: April 16, 2022, 04:36:32 pm
content: Making sure that insurance covers any equipment is a smart idea. I will have to do that.Also, what kind of protection protects receivers from ESD reliably when its so close!? We have lost two big trees from lightning in the last 15 years. I live in a mountainous area on a smallish hill between two mountains.We get our share, that's for sure!Well, Joe, glad youre okay! It looks like an opportunity to learn a bit and not too bad..it likely could have been much worse.I need to get much more serious about lightning protection myself.

author: cdev
author_rank: Super Contributor
timestamp: April 16, 2022, 04:38:26 pm
content: The (black walnut) tree that was hit by lightning just has a black stripe going through it from top to bottom. I dont think it did much meandering, as far as I can see from the outside. One branch was blown off and splintered.

author: Bud
author_rank: Super Contributor
timestamp: April 16, 2022, 07:40:31 pm
content: Quote from: cdev on April 16, 2022, 04:36:32 pmAntenna feeder inline protection devices with gas discharge tubes and the feeder grounded at the shack entrance. Do not think you can get any cheaper and effective. Do not bring gas discharge part inside the house, it would be silly. Should be installed outside.

author: twospoons
author_rank: Frequent Contributor
timestamp: April 17, 2022, 01:33:34 am
content: Back when I was working for an electric fence company we would get lightening hit units back fairly frequently. Some were repairable, the internal protection having done a semi reasonable job. But the ones that rattled ... every single component was a charred black lump, and all the copper was blown off the PCB and deposited inside the plastic case. Quite impressive.They eventually stopped the warranty on lightening strikes unless a diverter kit was installed on the fence - which consisted of an inductive feed to the fence (75cm of steel spring), a spark gap ( 2 fat bolts 2cm apart) and a 1.5m steel ground spike.