Will T.V. "attract" lightning
Will T.V. "attract" lightning
(OP)
When I was young I was led to believe that during a lightning storm that we turned off the T.V. because when left on it could attract lightening.
I still turn it off during a storm but usually don't unplug it.
What is the story on T.V. during a storm? Can it blow up?
Will shuting it off help?
I take it for granted that the cable is grounded somewhere.
Thanks
I still turn it off during a storm but usually don't unplug it.
What is the story on T.V. during a storm? Can it blow up?
Will shuting it off help?
I take it for granted that the cable is grounded somewhere.
Thanks





RE: Will T.V. "attract" lightning
Regardless it is advisable to turn the TV (and like devices) off during a storm as lighting, even strck a few miles away, could induce voltage spikes in the electrical distribution system that eventually could find way in the TV or any other applicace connecte to a plug. TV or like electronic devices being more sensitive to such voltage transients, it is a good practice to turn them off.
For news rely on a battery powered radio or mini-tv (battery powered) during an electrical storm.
( by the way I have none of those battery powered devices, but can advise nonetheless)
RE: Will T.V. "attract" lightning
If you are concerned about lightning/tv problems then do not turn off your devices, UNPLUG your devices! Large induced or conducted voltages can easily jump any tv power switches and indeed few tv's have power switches anymore, they really have wakeup and goto sleep switches.
On another note: DO NOT TALK ON HARD WIRED PHONES DURING THUNDERSTORMS
RE: Will T.V. "attract" lightning
I think I remember the rumor had something to do with the electrons in the up and powered T.V.
I think people thought that the electon gun of the T.V. caused a potential difference that would attract the lightening.
I think that if I turn the device off, that should be good enough because the circuit is broken and has no where to go (because open switch)
I dont go around unpluging stuff except my computer cable connection.
Come to think of it,why dont I unplug the T.V. cable??
Oh well, if a device fries, it fries.
I think I will look into insurance.
RE: Will T.V. "attract" lightning
I just seen your post after I posted the above.
You're right. Lighting is very high voltage and a switch is very small in comparison.
Thanks for the heads up about the phone. I would have never thought. I will tell my family.
So I take it that the phone lines are not grounded before they enter the house or are they?
Do telephones have some kind of insulation rating that they have to adhere to??
Thanks again. I'm going off to goggle things now
RE: Will T.V. "attract" lightning
RE: Will T.V. "attract" lightning
A good clean hit near a (rural) telephone line induces so much energy in the telephone line that it will clean out everything - including arresters. The remaining energy is more than sufficient to kill anyone holding the phone.
We have designed a little device called "the Cottage Guard". It is connected to the telephone line. It has a PTT style gas discharge 230 V voltage arrester and is isolated in a sturdy plastic box. In spite of that, we receive many that have more or less exploded from lightning energy. The reason they explode is that the box is closed and rather small. A TV will not explode since there is more ventilation openings that release the pressure.
Gunnar Englund
www.gke.org
RE: Will T.V. "attract" lightning
How is it then that TV transmitters sites, cell sites, etc. stay up and keep running in spite of direct hits..
I've installed and been maintaining equipment on a 1360 foot tall TV tower over a 10 year period that I'm sure has had many direct hits over the years.. and no outages due to lightning.
Unfortunately, the "GLEP" as it's called, the publication titled "The Grounds for Lightning and EMP Protection" written by Roger R. Block and founder of the Polyphaser corporation is out of print.. This document is worth its weight in gold when it comes to understanding how to engineer effective lightning protection.
The link below is the only document I've been able to find that has just a little bit of the info contained in the above document. http://www.arrl.org/tis/info/pdf/0208053.pdf
Guess I'll start storing my copy in the bank safety deposit box.
Polyphaser is highly respected in the communications industry for the effectiveness of their products.
http://www.polyphaser.com/kommerce_products.aspx
I've taken a direct hit to an antenna at the house that burned off the connections to the antenna, but there was no damage to the equipment connected to it at the time, thanks to an installation and protective devices installed per Block's document above..
RE: Will T.V. "attract" lightning
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TTFN
RE: Will T.V. "attract" lightning
There is a big difference between a TV tower or any similar structure and the common telephone line.
The main difference is that there is bonding and grounding of the structures as well as coaxial construction and spark gaps designed to take a lot of energy. None of these exist in a standard telephone installation. That's probably why you hear that "nothing is effective against lightning".
You haven't heard it in this thread, though. All that has been said in answer to a question about TV sets attracting lightning is that they do not - at least not more than other electric devices. And that an unprotected (or protected with "consumer quality" devices) telephone or terminal can be lethal to handle during a thunderstorm. And that is true and should also be told in an engineering forum.
Gunnar Englund
www.gke.org
RE: Will T.V. "attract" lightning
agreed!.. I'm appalled by the use of plastic housings and other weaknesses on some of these protective devices as mentioned in the part 2 article in the link posted above.. thanks for the link IRstuff!
I had one of the best I could find "consumer arresters" on my DSL line due to Polyphaser not making a suitable DSL line protector (i.e. let through voltage high enough for ring voltage AND the needed 1mhz bandwidth for DSL).
and it was just a matter of time before I lost the first modem due to telco line ground shift from a nearby lightning hit..
Afterwards I decided to try a Telco trunk model of IS-SPTL (shown in the part 2 article link above) in spite of the audio only bandpass rating. It works..guess not too great of high frequency attenuation and I'm on a short 1/2mile local loop.
btw, the application page for this protector shows a photograph of the unit being tested with a 40k amp surge! The 24AWG phone wire is vaporized off the unit by the 40kA hit on the input side yet, the measured output doesn't exceed the spec'd let through voltage.
pretty impressive!
RE: Will T.V. "attract" lightning
In any case, this is rarely a problem in So. Cal, at least in the coastal plains. We get maybe 1 lightning storm every couple of yrs. The mountains and high deserts get a lot more action.
TTFN
RE: Will T.V. "attract" lightning
Dr. Uman (or maybe it was Dr. Rakov) has a nice chunk of crystallized sand/silicon (fulgurites) about an inch thick, but hollow, like a silicon tube. Nice looking display piece created by the lightning strike spreading out among the sand.
Dr. Uman consults for Vaisala, whose system is used by the National Weather Service here in the U.S.
Here's a short article about the rocket setup...
http://www
Dan
Owner
http://www.Hi-TecDesigns.com
RE: Will T.V. "attract" lightning
I always think.. "I wish I thought of that!"
RE: Will T.V. "attract" lightning
When you have a good Faraday Cage, effective lightning protection is actually very easy. It can even be made to work in the absence of grounding, as with airplanes.
One of my pet peeves is suggesting that the same 'entrance protection' systems for lightning protection can be made to work to the same degree of protection when the systems are normal consumer grade and installed in various widely separated locations around the home, interconnected with fairly long wires, in a typical wooden-construction (RF transparent) house.
My opinion is based on real world experince where I've had several instances of equipment damage where the common factors include lightning hitting a nearby tree (obvious location - trust me...) and the damage occured to circuits connected to long (the longest) INTERIOR wiring (nothing to do with any outside wiring).
Entrance protection on a wooden house might certainly help in preventing fires, but a direct hit flowing down the antenna lead in will almost certainly induce 'minor' failures into anything electronic connected to longs runs of interior wiring.
Does anyone seriously think that a consumer grade TV is going still be working after a direct lightning hit onto the outside antenna - even if the cable is connected to a protection device and well grounded? Unlikely to be working, but at least it won't explode. It might even be repairable.
This is why it is a perfectly reasonable simplification to say that "nothing is effective" against lightning damage.
Unless as Step 1, you build a metal house...
RE: Will T.V. "attract" lightning
and the reference to the longest interior conductor indicates magnetic coupling or ground shifts are the likely culprit.. especially if there are multiple paths to the device on the longest interior conductor..
I made the same mistake years ago before learned more about the subject. I had unknowingly installed my TV in a guaranteed blow up situation with the power (and service entrance ground) coming from one corner of the house and antenna (and outside ground '68 feet away at far end of the house. And of course the flashover point between the two paths would have been on the circuit boards inside the TV.
In a lot of cases, you can't move or change the entry points to get rid of the loops, but by adding a common ground plate at the device with power and antenna protectors on the plate the flashover point is now inside the protectors. The TV now being on a stub, will only see the let through voltage of the respective protectors. While still on the loop, it could experience a ground shift voltage rise as a unit, but not major current through the device.
Many commercial sites have the same problem, simply because the area of interconnected equipment is so large, you have to be concerned about loop susceptability to magnetic coupling and ground shifts.. The TV transmitter site I mentioned in the first post is a brick building no faraday shielding inherent in the building.
I have the following on my wooden house now, I'm sure not fail safe under all circumstances, but "better than nothing"..
Lightning rods, a partial perimeter ground to various distributed ground plates and for tie down grounds from various ham antennas. All bonded together as recent NEC codes now clearly state and making a fairly decent birdcage without inordinate expense.
One known direct hit on an antenna with no damage other than the antenna itself.
RE: Will T.V. "attract" lightning
That statement represents a position that most reasonable people would agree with.
At the risk of beating a dead horse, compare the following:
1) A SW radio connected to a random wire antenna that goes up to the eve and out to a pole with a total length of about 100'.
2) An AC adapter powered telephone device connected to a unshielded telephone cable that goes up to the second floor and across to the other side of the house with a total length of about 100'.
In the first case, everyone 'knows' that you should provide entrance protection and grounding to help protect the radio in the event of a local strike. In the second case, everyone (including experts) pay it no attention whatsoever because it is 'inside' the (wooden) house.
RE: Will T.V. "attract" lightning
After all, you know what they say about lightning...
"I love deadlines. I love the whooshing noise they make as they go past." Douglas Adams
RE: Will T.V. "attract" lightning
RE: Will T.V. "attract" lightning
Dan
Owner
http://www.Hi-TecDesigns.com
RE: Will T.V. "attract" lightning
I got this email and thought it sorta fit in this discussion.
***** From Marine Surveying & Consulting ******
On the Panama Canal in 1994 I witnessed a truly large lightning strike.
It blew one of the mooring bollards out of the concrete quoin and threw it several hundred feet into the jungle.
Suddenly almost all of the nearby [within 500 feet or so] vessels radar scanners began revolving , and later there were many reports of fried electronics of all kinds, including some still new in their boxes.
The local telephone system also died.
One of the electric mules that assist the ships died in its tracks, some 400 feet away.
Apparently the Radio Frequency electromagnetic pulse was the favored culprit.
Several months, and dozens of government, insurance and university expert opinions and reports later, the best answer was that lightning can and will do whatever it wants to.
The one interesting thing was that the vessels with lightning grounding systems suffered LESS damage than the others.
Duck & cover,
Kristoffer A. Diel
***************** END ***************************
Seems bollards need lightning arrestors too!
RE: Will T.V. "attract" lightning
RE: Will T.V. "attract" lightning
"Our virtues and our failings are inseparable, like force and matter. When they separate, man is no more." Nikola Tesla
Member, P3
itsmoked (Electrical)
You speak of great and eternal truth.
zeitghost (Computer)
I have a memory of the robot in the good old tv series "Lost in Space" remonstrating with Will Robinson about the dangers of transmitting during a storm...
Barry1961 (Industrial)
Getting back to the original question: Will T.V. “attract” lightning?
Read the Eng-Tips Site Policies at FAQ731-376
RE: Will T.V. "attract" lightning
RE: Will T.V. "attract" lightning
"Will Robinson there is danger" etc.
RE: Will T.V. "attract" lightning
It depends on which show you are watching.
Barry1961