Ouch! Lightning fried my network

I checked, turns out there are TWO Jason's with the same optical airgap idea:

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Jasns R shmart

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As an electrical engineer I agree with you 100%. I believe the fallacy is "ground is ground". I had an excellent reference some years ago but have since misplaced it. The reference talked about volts per foot (distance) and why cows will be electrocuted while standing on the ground some distance from the lighting strike location.

I feel for you folks who are in those areas, I'm not at much risk here in New England but things have been known to happen. An article about a home getting hit by lightning (about 50 miles from me) listed some rather bizarre results.

  • Dog electrical fence was now in an open ditch. The dirt covering was blown away from the wire.
  • Nails popping out of the wallboard near outlets.
  • a number of others but the last listed was... After the house was all repaired they turned on the facilities, including the copper plumbing which had been off during the construction. They noticed some moisture building in the ceiling. Come to find out, there were (hundreds??) of pin holed in the copper water pipes !

BTW a nuclear plant optoisolator is about a meter long (between copper).

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20 years ago, an electrician called me about a repair job near here. The house had apparently take a direct hit --even peeled the vinyl siding off on one wall. The house had propane tanks with copper tubing for gas lines. Plumbing under the house was copper. The lightning fused the two together and they were getting water out of the LP lines.

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I will say I've worked with some absolutely excellent electrical engineers.

However when it comes to the topic of grounding, weird stuff happens. Transient stuff happens. It is difficult to conclusively troubleshoot transient/intermittent problems.

So while I always believe them when they show me the data, I'm always open to the thought that their data might not be capturing the actual incident.

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It is difficult to conclusively troubleshoot transient/intermittent problems

Especially since we have no way to simulate or even measure when or where it occurs.

I don't see how an electronic engineer (or any engineer) can be so naive (?) as to think test data could predict the effects of a lightning strike. I would more believe historical data on the results of past strikes.

It seems to me all the we can do right now is to add methods to entice the lightning to go somewhere else and hope for the best.

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So, if one just wanted to provide protection for CT 6 runs buried undergound between buildings or to outside APs, what would you folks suggest?

We live in Maine, but thunderstorms are becoming more of a problem than in years past. Last year, we lost a couple of switches (one managed, one unmanaged) when lightning struck nearby. We have three runs of Cat 6 buried between buildings on the property, plus two other runs that go to access points at the docks. I think I would also like to protect the line coming in from Starlink if possible. Advice appreciated - thanks in advance.

ALSO: We just had a bunch of metal helical piers (screw-in posts) installed as part of a deck repair. They're about 8 feet down in the ground, 2-3" in diameter, and attached to nothing but the wooden deck framing. That seems like an ideal grounding rod although they're not copper, of course. Any thoughts on that?

They should be fine. My grounding rods are simply steel....

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Good thing this wasn’t in use

Story was lightning hit the vent stack.

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Damn. AFAIK, my vent stacks are ABS. Presumably, there must have been combustible gases in the system?

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With the amount of energy in a lightning strike, anything is combustible (kinda) air turns to plasma :slight_smile:

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I was really enjoying what I was learning by reading this thread, and then you two have to go and give me nightmares...geez, that looks crazy/scary.

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Remember bean counters are part of the design process here.

If I had lighting issues, I would be tempted to bolt the arrester to the ground rod.


Just a far out thought. High frequency currents are conducted only by the outer "skin" of a conductor. Copper or steel or aluminum. This is well known and called the "skin effect".

The typical rise time of a lighting strike is about 1 µsecond, roughly equal to a 400kHz signal.
In copper, the "skin effect" of a 400kHz signal is approx 80µm (aka 0.08mm or 3 thousands of an inch). This being the case, larger diameter conductors (more surface area) will perform better at conducting lightning energy to someplace else than smaller. This is a "duh" statement right?
However in the larger diameter conductor the center material is not being used, i.e. wasted.

So in theory (I've found no study data) a soft copper tube could be better than the same copper volume in a wire form.
Just food for thought.

Yea and our stacks (plumbing vents) are copper.

Another aside.....

We recently had a new roof installed. The old vent stack seals had deteriorated to the point of leaking. The seal wasn't that old, maybe 10 to 12 years. I asked the roofing contractor about it. He said the UV breaks down the seal material. He uses normal vent seal but adds an ABS cover that looks like a toilet plunger with a opening through the center. Basically blocking off any UV to the original seal. In addition at the top there is a cap that stops water from going between the vent and this outer cover. Real neat idea. Had I though of UV when I installed the old seal I would have covered it with flashing.

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COPPER flashing ...lasts about 100 years. I keep a pallet of 4' x 8' copper sheets just for flashings.

Yeah, I've double-flashed roof vents. Bed liner or, in a pinch, spray undercoating holds up pretty well.

toilet

I saw that. The odd thing was that there was a 2nd picture showing a blast hole in the ceiling almost directly above. So, if the strike followed the vent pipe, it jumped to the grounded basin somewhere above.

Lots of things strange about this photo. Like if the lightning was already in the plumbing system why would it take a side trip to the toilet?
But it was fun to look at.

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The next time you are by your car/truck/etc take a look at the sidewalls. Older tires will have very fine cracks. This is also caused by UV rays.

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Me too...I had no idea I was made of rubber!!

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Some good tire analysis on Twitter
https://twitter.com/trenttelenko/status/1521182849000423426?s=21&t=4j5vSiDhnKOjp0jwN__Obg

That would be my story, too, if i tried to flush an M80 down the toilet. :wink:

Edit: Or maybe the moral of the story is not to go near the Diablo Maximus Breakfast Burrito.

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