Lightning struck near my house.....

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  #1  
Old 06-01-17, 11:42 AM
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Lightning struck near my house.....

and I'm finding the display ports (HDMI, VGA, etc) on a number of devices are no longer operational. The devices power on, but produce no picture.

For example, a Stereo receiver with HDMI pass-through and my Roku are no longer producing signals. Ironically, both are powered by "slightly-higher than entry-level" surge protectors.

I verified all HDMI cables are working fine.

All the coaxials for cable are connected to cable boxes...none of them are connected directly to the TVs.


I can't wrap my head around this.
Why would displays ports be affected by this? And why would none of these devices die outright?
Could the surge have come through the coaxial line and somehow passed through the cable TV box onto other devices attached to the TV?
 
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Old 06-01-17, 11:55 AM
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Could the surge have come through the coaxial line and somehow passed through the cable TV box onto other devices attached to the TV?
Very likely.... depending on well grounded the cable line is.

Lightning doesn't always follow any predictable pattern. If it's a direct strike the amount of power is incredible and it can jump thru and follow many different paths.
 
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Old 06-01-17, 12:01 PM
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Hi Hans,
It is next to impossible to determine just where the bounce from that strike went. Lightening is far too powerful to be protected against in most cases. One approach is to redirect an incoming strike with lightening rods. But an actual hit to your house would be extremely rare. As for a bounce (my term for a surge) entering your home, that can be on any wire or metal (like plumbing copper) pipe. The trick is, to get everything to jump together. If one point goes high while another remains low then the difference between those points can cause the damage.

I worked at the circuit board level but have done some static problem resolving and for the most part it is trial and error.

Having been hit a few times at my home and business (not me personally) I was able to get my insurance to cover the damage. Not sure if they will still do that.

Best,
Bud
 
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Old 06-01-17, 02:54 PM
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A big problem occurs when the power mains/system takes a surge and the cable becomes the ground path. There will be a time when the cable shield conducts a lot of surge current into the cable system. I took a hit a couple of years ago, and even though there was a little #14 bonding wire from cable shield to service entrance ground, it wasn't enough.
The "cable box" might be the only item to attach to coax directly, but there are likely non-galvanically isolated paths to the receivers, etc that conduct this same current.
 
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Old 06-01-17, 08:13 PM
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Very likely.... depending on well grounded the cable line is.
I don't know the technical term, but the coax line outside the house has some sort of grounding "splitter" attached to it. That "splitter" is grounded to the electrical meter using a 12 or 10 gauge wire.

Would a thicker gauge wire help at all?
Or possible attaching it directly to the grounding rod underneath it?
 
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Old 06-01-17, 08:21 PM
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A big problem occurs when the power mains/system takes a surge and the cable becomes the ground path.
I don't know if that is the case here.

I'm pretty sure the power never actually went out.

In addition, the GFCI outlet in my communication closet was tripped, post strike. These outlets power my cable modem, router, network switch, etc. I have GFCI outlets throughout my entire house, but this was the only one that was actually tripped. The coaxial lines are in this closet too, but I don't believe they directly connect to any of the outlets....just to the cable modem.

Of course, all of the devices in this closet are OK...so, again....can't wrap my head around any of this.
 
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Old 06-01-17, 08:25 PM
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The power doesn't have to go out. The high voltage hitchhikes on anything it can. Electrical lines, cable lines, phones lines, fences, trees.

You don't visually have to have seen it in your house for it to have been there.

You had to have some type of voltage imbalance to ground for the GFI to trip
 
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Old 06-02-17, 04:29 AM
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Lighting hit the tree in front of my house and I lost several items. Some sitting next to each other, one went bad the other ok plugged into same outlet.
 
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Old 06-02-17, 06:55 AM
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If your interested, here is a data sheet on a typical, maybe even high end, HDMI quad input transceiver chip. It runs on a 1.8V dc power supply. If power exceeds 2.2V, it dies. THe inputs are not galvanically isolated from this chip. When you unleash even the residual effects from a close lightning strike, these things die quickly.

http://www.analog.com/media/en/techn...ts/ADV7630.pdf
 
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Old 06-05-17, 09:02 AM
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When it comes to lightning you can only do so much to reduce the risk of damage to electronics. A close-enough strike will inevitably damage consumer electronics no matter how well it is grounded or what kind of surge protectors you have. There can even be damage in unplugged equipment from induced currents. Commercial radio broadcast sites spend hundreds of thousands of dollars on lightning mitigation and stuff still gets damaged with a big-enough strike. It's no different than any other force of nature: we can try to protect ourselves, but nature often wins.
 
 

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