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True or False: Tying a knot in a power cord "provides protection against lightning"

Hedges said:
MOVs like that, yes.
Be sure to get a high enough voltage that it isn't conducting at all before there is a spike.

They can take thousands of amps, and some number of Joules. Multiple hits, eventually worn out. Various brands and ratings.
SMA put some on PV inputs of some models, user replaceable, recommended periodic replacement in lightning regions.

A big box I got surplus had two sets of 3 (each probably multiple MOV in parallel. One set lower voltage, another higher voltage, indicator lights if any blew out.
Click to expand...
If these are cheap parts isn't there a decent Midnight SPD knockoff coming out of China? Same or similar level of protection without the $125/each price tag.
 
I'll call it "induced current" rather than "charge build up" being bled off. But maybe both magnetic and electric coupling occur.

Square D and others have some in the $75 to $150 range. I found a box of 5 on eBay for $250, putting in several panels.

These parts are worth a few dollars, while parts in most electronics are dirt cheap. That could limit what functional knock-offs are available.



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And you'd want to test them, as I did.

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Testing Metal-Oxide Varistors (MOV)

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kolek said:
There are articles online claiming that typing a knot in a power cord will provide protection against lightning. For example, this one.


Could tying PV cables in a knot provide any lightning protection? These are 400V 12A DC lines. Or alternatively, could a coil like this reduce solar production? In my case, I'm tying off my PV cables to my rack to isolate them during earthquakes from being jerked out of their connections to my inverter.

Personally, I'm skeptical of the "lightning protection" claim, but I'd like to hear what the experts here have to say. I specifically interested in hearing from people who have tested this or can provide sound electrical engineering arguments why or why not this is legit.

"If it worked, everyone would be doing it and nobody would sell lighting suppression equipment." Sure, we all know that. But that's not scientific proof, so I'm still curious if anyone here knows the actual science.

View attachment 227905
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😂🤣🤭😅🤣😂😅 Clearly they never seen lightning hit a home or garage and done insurance write up of the damage lightning does… this so false the false is false… lightning jumps to anything metal feet away through cables like magic and can destroy things near that are not plugged in, an amazing thing to see and write damage reports for. That metal shelf will take that lightning and fry everything on it if it is a near hit.
 
Mkgough said:
😂🤣🤭😅🤣😂😅 Clearly they never seen lightning hit a home or garage and done insurance write up of the damage lightning does… this so false the false is false… lightning jumps to anything metal feet away through cables like magic and can destroy things near that are not plugged in, an amazing thing to see and write damage reports for. That metal shelf will take that lightning and fry everything on it if it is a near hit.
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You're describing direct lightning strikes, and nobody claims this, or anything else for that matter, is protection against a direct lightning strike.


If you're unclear on what we're discussing, @Bananaman321 spelled it out in his comment below:
Bananaman321 said:
Most of what we're trying to bleed off is residual from a near by strike
Click to expand...
 
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Bananaman321 said:
Most of what we're trying to bleed off is residual from a near by strike
Or utility line voltage spike From a line strike
Click to expand...

kolek said:
Nobody claims this, or anything else for that matter, is protection against a direct lightning strike.


@Bananaman321 spelled it out in his comment below:
Click to expand...
The chances of a direct Lightning strike are like winning the lottery

That's why I don't play the lottery

That why I take my boat out in thunderstorms

Problem is you don't need a direct strike to f*ck your sh*t up

And that's why we blow harder money on these overprice Christmas lights (SPD's)
 
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My main spd on the house is attached to the main breaker so the main breaker cuts out with any surge, seems to reset just buy closing the main breaker but unsure how many triggers it would take before it fails. Although I've never seen lighting make landfall here (always sheet lightning) the SPD has activated regularly when a drunk decides to play chicken with a 33kv pole (guessing it's poorly made concrete I know Hilux's are strong but they seem to fold almost 1m² concrete poles in half) so atleast on the houses main incoming we tend to buy the best SPD/main breaker available here.
 
DPC said:
This video shows a typical strike near the infrastructure....
But not at the exact location.
If the strike had hit the pool there would have been damage.

What we see here is the current from the strike travelling around the area seeking out paths to ground to discharge that are better than the point of contact.
Maybe the hit was on a pole line within the area...
But if your grounding systems in the area are not up to snuff that energy will travel to other grounding rods through metal around the area.
Pools, if built to code will have all the steel supports grounded.
Fences maybe not grounded well we don't know....

In a switch yard you know the fence is going to be tied to the ground grid and everything bonded together ( like gates and doors.. )

in this video we can see an arc but its not at all clear what is going on or how its travelled this far.

In someplace I have seen ground plates in lakes because it was the best way to ground a power system on a rocky area.
I don't know what is happening here.
I suspect we see a strike following a ground cable to a plate in this body of water and the resulting steam explosion in the water...
I suspect because I cant be sure.
Maybe there is something else filmed here....
Maybe thats a shock tube leading to water and someone is blasting rocks in that channel.

Youtube videos can be hard to trust.
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The reddish-brown fumes coming from the water after the explosions in the second video is a clear tell that explosives were in use, and probably the lightning set them off. The reddish brown color is from from the gas nitrogen dioxide, which is especially made by ammonium nitrate-based explosives. For a much bigger example of this effect, see the video of the giant Beirut explosion a few years ago. Lots of red-brown fumes - coming from millions of pounds of ammonium nitrate. (Stored in a major port, in a major city, next to fireworks. Important safety tip: Don't do this.)

I don't have any at my fingertips, but I've seen videos of when lightning strikes water, and there are no explosions.
 
Sergio95050 said:
That's why when you're reposting something "hot" have a diligence to check it and make your own disclosure. Or do not spread FUD!
Click to expand...
FUD hot reposting why don't spread you're diligence disclosure own make. Sorry, just kidding. I have no idea what that sentence meant.
 
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outsider said:
Ok, here's a video of a lightning strike on water. No explosion.

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I would think it would depend on how much energy could be displaced, a small body of water might well cause a steam explosion but the chances of a lightning strike are slim enough, hitting a small body of water you just so happen to be recording to present evidence has an infinitesimal chance
 
Hedges said:
MOVs like that, yes.
Be sure to get a high enough voltage that it isn't conducting at all before there is a spike.

They can take thousands of amps, and some number of Joules. Multiple hits, eventually worn out. Various brands and ratings.
SMA put some on PV inputs of some models, user replaceable, recommended periodic replacement in lightning regions.

A big box I got surplus had two sets of 3 (each probably multiple MOV in parallel. One set lower voltage, another higher voltage, indicator lights if any blew out.
Click to expand...
really? i would be curious to see links for these. don't need them at the moment, but always looking for redundancy/ Kolek is not wrong about the midnite solar SPD's and cost.
I went a little crazy after blowing up my inverter and not having full house power for the three weeks it took for my second inverter to arrive. I powered the fridge and freezer and a couple fo lights off of my campers inverter while i waited, but had to run anything in the shop off of my gensets... lots of wasted fuel while waiting for the new inverter and spd's to arrive.
 
Daddy Tanuki said:
if that happened near me on a larger body of water i would be tossing out nets and gathering dinner.
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My wife's cousin lives next door we have a large pond filled with snakefish and catfish in between us he's spent months making traps out of scrap he's had laying about, catching maybe 1 fish a week. His brother in law turned up one day with what was essentially a microwave transformer a battery and two grounding rods emptied the whole pond of fish in maybe 15minutes. Me and my wife spent hours laughing at the cousin and his months of hard work.
 
ThaiTaffy said:
My wife's cousin lives next door we have a large pond filled with snakefish and catfish in between us he's spent months making traps out of scrap he's had laying about, catching maybe 1 fish a week. His brother in law turned up one day with what was essentially a microwave transformer a battery and two grounding rods emptied the whole pond of fish in maybe 15minutes. Me and my wife spent hours laughing at the cousin and his months of hard work.
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yeah back when I was younger and a little more apt to thumb my nose at the conservation officers we used a car ignition coil a battery and a rotary contact switch crank the switch and it turn the 12 volts off and on rapidly which stimulated the coil great if you had a fiberglass canoe, not so good in an aluminum john boat. learned to carry a dry piece of plywood after screwing that up... my grandfather who was with me, watched me do and laughed. he was sitting on a rubber mat and wearing shoes...i was barefoot. grandfathers and crazy uncles, where would we be without them?
 
outsider said:
ammonium nitrate-based explosives.
Click to expand...
Hmm...
I was looking at that thinking I saw red too.
But I have never seen underwater blasting done and I have no idea what was used.

Probably something else, you wash away an ANFO spill because its water soluble.
Maybe emulsion pumped into a plastic liner??

Not an explosives expert.
I split when I see any sort of blasting preparations.
I want nothing to do with it, I won't even be around if I suspect they are looking for guards.
 
kolek said:
I'd be interested in a cheap DIY replacement for the Midnight SPD. I checked and found:

Is that what you're referring to?

Spec says "can withstand peak surge currents from 6,000 A to 10,000 A"

A single lightning bolt is extremely powerful; measured in thousands and hundred thousands of amperes (kiloamps or kA).

Basically you want something that will destroy itself and save your equipment. Would that work?
Click to expand...


The midnight SPD looks to have MOV, TVS diodes, and spark gaps inside the cover that I can see. Typical lightning suppressors are a stack of protection that start at a certain voltage and continue on up. They are not typically just 1 device.
 
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A tear-down would be good. All I can see in the photos are MOV and LED.

Different speeds for different parts.
I've used other things to protect instruments. Seems to be just MOV that I see built into inverters.
Lightning I think is relatively slow, up to 100 kHz or no not GHz like some threats.
Other stuff outside could help for sites with more lightning activity.
 
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