HDMI Cables and lightning! - AVS Forum
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post #1 of 5 Old 06-25-2012, 07:27 PM - Thread Starter
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During a storm over the weekend, a lightning strike hit my gutter...3 of my flat screen tv's no longer powers on (I get power indicator lights, but that's all), same with Blu Ray player Xbox 360 audio receiver, and DTV DVR. Both the DTV and cable modem cables went out as well. eek.gif

All were hooked up thru HDMI cables. If I have to buy new TV's etc, should I go out and buy all new HDMI's? Does anyone know if these can be reused?
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post #2 of 5 Old 06-26-2012, 01:05 AM
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They might be OK and there should be no issue in trying them when you get the new gear. For the small cost of replacing them (get them with the rest of the gear on insurance), I'd just get new ones.
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post #3 of 5 Old 06-26-2012, 06:09 AM
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Quote:
Originally Posted by dvdguy123 View Post

During a storm over the weekend, a lightning strike hit my gutter...3 of my flat screen tv's no longer powers on (I get power indicator lights, but that's all), same with Blu Ray player Xbox 360 audio receiver, and DTV DVR. Both the DTV and cable modem cables went out as well. eek.gif
All were hooked up thru HDMI cables. If I have to buy new TV's etc, should I go out and buy all new HDMI's? Does anyone know if these can be reused?

Your HDMI cables may or may not be damaged. I'll bet that they aren't damaged but lightening can do what it wants. I've seen tons of equipment damaged by lightening, and the cables have never been damaged in any way. It can take only a few dozen volts to damage a audio/video input or output, but it takes thousands of volts and a ton of current to damage the cables.

This is why I keep telling people to get whole-house surge protection if they are out in the country or in an area with a history of surges. Please post about where you live.

You'll only know if you try them which can't hurt anything. If you buy new cables forget local sources that generally want upwards of $40 for 1 meter cables. The inexpensive HDMI cables that I've obtained from online sources like Amazon and Meritline work just as well, and save you upwards of 90% of the cost. You can pay for next day shipment and still save money. But, save your money until you know for sure that you even have a problem. Likely, its anything but the cables.

If you are in doubt pull the signal cables and see if any of the equipment starts powering up. I'd be totally surprised if it was damaged or was causing any problems. The damage more likely than not came in through the power line.
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post #4 of 5 Old 06-27-2012, 07:13 AM
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Quote:
Originally Posted by dvdguy123 View Post

During a storm over the weekend, a lightning strike hit my gutter...3 of my flat screen tv's no longer powers on (I get power indicator lights, but that's all), same with Blu Ray player Xbox 360 audio receiver, and DTV DVR. Both the DTV and cable modem cables went out as well. eek.gif
All were hooked up thru HDMI cables. If I have to buy new TV's etc, should I go out and buy all new HDMI's? Does anyone know if these can be reused?

When lightning hits a nearby object, the bolt will cause a very large magnetic field that will rise then fall in intensity. When it does this, any loop of conductor in the area will generate a voltage around that loop. Sometimes that voltage can be very high, depending on where the bolt was and how the loop is oriented in relation to the bolt. Expect numbers from 40 volts per square meter to 400 volts per square meter. Meaning, a loop which is 3 foot by 3 foot could generate between about 40 to 400 volts.

Your tv's, the wall outlets and your cables will all form loops. You generally have no control over the location of the AC wires in the wall, and may not even know what path they take, so a daisy chained set of outlets won't even help you.

In addition, where your cable to the house comes in is also very important. The cable should come in at the same location as your AC, and it should also be bonded electrically to the earth rod at the service feed location.

There are two typical methods the bolt will kill appliances. Without an autopsy, it is not possible to determine which avenue of entry killed your tv's.

1. Via the power lines, hot to neutral/ground. A whole house surge protector will protect you against hot/neutral/ground voltage potentials exceeding about 350 volts. It will NOT protect any devices against a nearby strike that induces loop voltages, as the voltage will not appear across hot/neutral/ground for the whole house SPD to see.

2. Loop voltages. When you connect all the devices together, you make loops. If that bolt's magnetic field can get within the area of a loop, it will create a voltage. In general, AC power is kept apart from the cable lines, so loops form there. To protect tv's against that, you need a surge outlet protector which also has ports for hdmi, cable, and AC. Any wires that go to the appliance should come together at one of these strips. Multiple appliances need multiple outlet strip protectors, one used on one side of the room will not protect the other side of the room if it is a nearby strike loop voltage.

ps. You'll have to test the HDMI's with known good equipment. Perhaps bring them to a big box store and ask them to try them.. As arkn said, I'd be surprised if they were destroyed, but we are talking about lightning.

Cheers, jn

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post #5 of 5 Old 06-28-2012, 01:39 PM
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Quote:
Originally Posted by dvdguy123 View Post

If I have to buy new TV's etc, should I go out and buy all new HDMI's? Does anyone know if these can be reused?

I've had cables fail from trying to deliver too much power but it was
always easy to see they were damaged. It's hard to overlook missing,
melted, or burned insulation, bare copper wires, etc.

However, even short HDMI cables needn't cost more than about
US$1 per foot. I might replace them just to avoid a minor worry.
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