Originally Posted by dvdguy123
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.
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.