Power surge?

[need2shave 0]

I recently had a customer have me come out to inspect their Dahua NVR because it was beeping. When I arrived I was surprised to find the VGA cable to their monitor was completely melted through. I assume this was due to a lightning strike...has anyone else seen this happen through the VGA cable? Cameras and power supply were fine likely since they were protected by surge protectors.

[Securame 0]

And you didn't take any pictures for us to see?

[SectorSecurity 0]

I have never seen this in all my years working with computers and CCTV equipment, would have been cool to see a picture.

[ssmith10pn 0]

Sounds more logical to me that the power supply went haywire in the monitor.

[need2shave 0]

I did take a photo with my phone and I'll get it uploaded soon.

[need2shave 0]

Attached is a photo.

[hardwired 0]

That looks to be damage cause by an electrical fault. Lightning tends to make things explode, rather than melting them. (possibly an open neutral on a MWBC, internal failure on monitor, etc.)

 

You need to thoroughly check for faults in your wiring before connecting anything else.

[SectorSecurity 0]

Is the monitor and DVR plugged into the same wall outlet or different outlets?

[coyoteknee 0]

This could mainly be caused by a defective VGA cable or something internal in the monitor.

[ivan_sh 0]

it is no relation with the lightning.

[ssmith10pn 0]

Is the monitor and DVR plugged into the same wall outlet or different outlets?

 

I see where your going with that. Maybe one plug has an open neutral and it pulled it's neutral through the VGA cable?

[westom 0]

I recently had a customer have me come out to inspect their Dahua NVR because it was beeping. When I arrived I was surprised to find the VGA cable to their monitor was completely melted through. I assume this was due to a lightning strike...

Lightning does not have sufficient energy to do that melting. AC utility electricity does. Lightning can create temporary connections (ie plasma) that would connect AC power (the follow through current) to that cable. But then fuses should have tripped to avert damage that extensive.

 

Surge protectors would have done what their manufacturer said it would do - nothing for the typically destructive type of surge. Did you really think that power strip (hundreds of joules) would absorb the energy of a surge (hundreds of thousands of joules)? Did you really think a 2 cm inside that strip would stop what three miles of sky could not? It doesn't. It does not claim to protect from the other and typically destructive surge (lightning is only one example). A typically destructive surge passes right through as if the adjacent protector did not even exist.

 

So the question is what would have provided sufficient energy to melt or burn a signal wire? Any sign of flame?

 

How many amps would be necessary to cause a copper wire to melt? Maybe 25 amps per wire. Where did that much current come from? Good question. So there must be more to the story. Wire that did not meet insulation standards? Signal wire that was even thinner? Fuse that was compromised or missing. Maybe even a wiring fault inside the wall receptacle? Some are only a problem when multiple other faults also exist.

[MaxIcon 0]

Lightning is absolutely capable of melting something like that. It's very unpredictable in its patterns, but regularly fuses and burns all kinds of items, like this melted sidewalk from a lightning strike:

 

Here's a whole collection of photos of stuff melted by lightning:

http://www.notjustrocks.com/wst_page6.html

 

That said, it's rare for lightning damage to be constrained in that small an area - it frequently jumps from point to point due to the high energy. You'd have to do a failure analysis on the monitor and NVR to see what caused the damage.

[westom 0]

Lightning is absolutely capable of melting something like that.

Apparently a relevant expression was ignored. A professional who does this stuff defines what is relevant:

Although lightning strikes have impressive voltage and current values (typically hundreds to thousands of kV and 10-100 kA) the energy content of the discharge is relatively low and most of the damage to power plant is caused by 'power follow-through current'. The lightning simply provides a suitable ionized discharge path.

We all also learned an important concept in elementary school science. Conclusions from observation are classic junk science. (Other examples are spontaneous reproduction or moldy bread breeds maggots.) Colin Bayliss explains that damage in his book. Your conclusion is speculation based only in observation.

 

In other research, Alan Taylor demonstrated that most all lightning struck trees (>90%) have no appreciable indication. Another example of less energy in a lightning strike. But some see the rare exception. Then, using speculation only from observation, assume that major tree damage is due to massive energy in lightning.

 

Using same reasoning, a car's spark plug also created so much energy as to move the car. Reality. Spark plug simply ignited something with higher energy inside the engine - gasoline. Lightning simply ignited something with higher energy inside the tree - sugars. Sugar (not lightning) was the high energy source that did damage. But that means learning basic science rather than creating a junk science conclusion only from observation.

 

Most damage from lightning does not even create a visual indication. However a higher energy source (follow-through current) can create significantly greater damage. Many just *assume* energy was from lightning rather than learn the underlying science. Knowledge also means numbers. Such as those summarized by Colin Bayliss in his book.

 

Learn science (ie read the books) before jumping to conclusions based only from observation. OPs observation suggests a high energy source that could only exist with a failure elsewhere. To say more would require not provided information such as wire gauge, wire insulation, household wiring mistakes or faults, etc. Information that would explain a higher energy source to cause a potential fire condition.

 

I would be concerned. Because other 'required functions' should have made that 'threat' irrelevant.

[hardwired 0]

Another possible fault may be associated with a defective camera power supply, or ground fault current on the coaxial cable. Some DVR's of that type use a switchmode brick type power supply that doesn't pass ground through to the DVR, so a fault current on the coax shield would find a ground through the monitor cable (which does typically provide a ground).

 

In any case, some further testing is warranted, for the safety of the people using the equipment, as well as the devices. Whatever is passing enough current to melt a cable is also probably at a voltage high enough to kill someone coming in contact with it under the right (wrong?) circumstances.

[daveshoot 0]

Your conclusion is speculation based only in observation. blah, blah.

 

Jeez. It doesn't look like lightning damage to me and I'd look at other causes, such as ground faults, but the OP didn't do anything wrong here.

 

If you're a retired engineer or professor, and scolding is your normal tone of delivery, try actually helping, as in "check resistance between x and y" or something.

 

Keep in mind this was on the VGA plug, not primary AC, and volunteer something useful. This is an egregious failure and while I have seen a lot of surge damage, I've never seen melting like this on a VGA connector.

 

Lightning is usually catastrophic and instantaneous and blows stuff up. If lightning had caused that melt, there would be plenty other damage besides (and there may be anyway). That looks like sustained high current draw.

[need2shave 0]

They had the monitor plugged into a different outlet than the nvr. The monitor is still functioning.

[westom 0]

They had the monitor plugged into a different outlet than the nvr. The monitor is still functioning.

Assuming a typical wire size in that video cable, the "sustained high current draw" would be on the order of 20 or 30 amps (volts are irrelevant).

 

So, what are potential sources of that "sustained high current"? And what 'protection' did not avert the damage? Those questions suggest a few and likely reasons for that damage.

[MaxIcon 0]

Apologies for the off-topic thread derail; skip this post if you don't care...

 

Lightning is absolutely capable of melting something like that.

Apparently a relevant expression was ignored. A professional who does this stuff defines what is relevant:

Although lightning strikes have impressive voltage and current values (typically hundreds to thousands of kV and 10-100 kA) the energy content of the discharge is relatively low and most of the damage to power plant is caused by 'power follow-through current'. The lightning simply provides a suitable ionized discharge path.

We all also learned an important concept in elementary school science. Conclusions from observation are classic junk science. (Other examples are spontaneous reproduction or moldy bread breeds maggots.) Colin Bayliss explains that damage in his book. Your conclusion is speculation based only in observation.

 

In other research, Alan Taylor demonstrated that most all lightning struck trees (>90%) have no appreciable indication. Another example of less energy in a lightning strike. But some see the rare exception. Then, using speculation only from observation, assume that major tree damage is due to massive energy in lightning.

 

Using same reasoning, a car's spark plug also created so much energy as to move the car. Reality. Spark plug simply ignited something with higher energy inside the engine - gasoline. Lightning simply ignited something with higher energy inside the tree - sugars. Sugar (not lightning) was the high energy source that did damage. But that means learning basic science rather than creating a junk science conclusion only from observation.

 

Most damage from lightning does not even create a visual indication. However a higher energy source (follow-through current) can create significantly greater damage. Many just *assume* energy was from lightning rather than learn the underlying science. Knowledge also means numbers. Such as those summarized by Colin Bayliss in his book.

 

Learn science (ie read the books) before jumping to conclusions based only from observation. OPs observation suggests a high energy source that could only exist with a failure elsewhere. To say more would require not provided information such as wire gauge, wire insulation, household wiring mistakes or faults, etc. Information that would explain a higher energy source to cause a potential fire condition.

 

I would be concerned. Because other 'required functions' should have made that 'threat' irrelevant.

 

So, you're saying the melted sidewalk in the picture above, and the fused sand in fulgerites, are caused by "power follow-through current"? If not, where do you believe the energy to create these effects came from?

 

...most all lightning struck trees (>90%) have no appreciable indication.

...some see the rare exception.

...Most damage from lightning does not even create a visual indication.

Are you also saying that some lightning strikes, do, in fact, have sufficient energy to cause damage, even where there's no source of "power follow-through current"? Either it's possible or it's not; if there are exceptions, then this is not "speculation based only in observation". All it takes is a single exception to disprove the rule, as I'm sure you know.

 

Learn science (ie read the books) before jumping to conclusions based only from observation.

Lol! Yeah, I've read a few books. I'm an electrical engineer, and have spent over 30 years working with equipment using power sources of hundreds of kV.

 

I've personally seen a saguaro cactus blown to pieces by lightning, and I know someone who was struck by lightning in a boat in a lake, melting the bottom of their cooler (and blowing open all their cans of beer), causing much more damage than this connector had.

 

However, just to cap off the pedantry, note that I didn't actually say lightning caused this and indicated it was unlikely, though possible:

That said, it's rare for lightning damage to be constrained in that small an area...

 

I like to do other people's research for them, so here are a few more exceptions, showing sufficient energy to cause major damage:

 

[SectorSecurity 0]

I would have them check their outlets, or have them checked by a licensed electrician, if the monitor and DVR were plugged into different outlets there is a possibility one outlet is wired incorrectly and causing a fault.