Discussion in 'General Science' started by Lightfire, Jul 2, 2012.

  1. Lightfire

    Thread Starter Well-Known Member

    Oct 5, 2010

    Every time there is a big lightning in our house, we have to turn off the television because of the tendency that lightning would touch the antenna and therefore the TV will be damaged (TV screen colors will be reddish or so).

    Is that true? How?

    Thanks you!
  2. wmodavis

    Well-Known Member

    Oct 23, 2010
    If there is lightning IN you house I would get out immediately if not sooner.
    How would turning off the TV stop the lightening from 'touching' the antenna?
    If the TV is still connected, whether on or off, and if lightening strikes your TV antenna the TV will be TOAST!
    Last edited: Jul 2, 2012
  3. BMorse

    Senior Member

    Sep 26, 2009
    Just as a precaution, I usually unplug all my computers and sensitive devices when there are real bad thunderstorms in our area.... a small lightning surge hitting a tree nearby can still turn a lot of your electronic devices into bricks :)
  4. PatM

    Active Member

    Dec 31, 2010
    Depends a lot on where you live.
    South Carolina, Georgia and Florida have a lot more destructive electrical storms than some other states.
  5. MrChips


    Oct 2, 2009
    If you are expecting a severe thunderstorm in your area you should not just turn off the power but unplug the AC power cable from the wall and disconnect TV antenna and modem cables.
    BMorse likes this.
  6. Lightfire

    Thread Starter Well-Known Member

    Oct 5, 2010
    hello, im thinking this one... the transmitter tower of tv stations. what would happen if lightning strikes that tower????
  7. absf

    Senior Member

    Dec 29, 2010
    Telecoms towers have lightning arrestors which conduct the lightning directly to the foot of the tower. The ohmage of the earthing system there must be lower than a certain value (depending on the geology of the location of tower) to get approval. The communication dishes and transmitter antenna (TV & FM radio) are installed at lower altitudes than the lightning arrestors.

  8. westom


    Nov 25, 2009

    View AC electric and other utility wires down the street. If lightning touches those, then lightning is connected to every appliance in your house. Lightning does damage on a path to earth. Once inside, it will hunt for earth destructively via appliances. Even on paths you don't know are electrically conductive. Unplugging is an unreliable solution.

    For over 100 years, direct lightning strikes without damage. But only in facilities that learn some basic concepts even demonstrated by Ben Franklin in 1752.

    Lightning was using an eclectically conductive material (wooden church steeple) to obtain earth ground. Wood is not very conductive. So lightning's 20,000 amps created a high voltage. 20,000 amps times high voltage is high energy. Church steeple damaged.

    Franklin put a lightning rod atop the steeple. But a rod does not do protection. The rod only connected lightning to earth on a conductive path. 20,000 amps created a near zero voltage. 20,000 amps times a near zero voltage is near zero energy. Nothing damaged.

    You must do same. Every wire that enters your building must first connect to earth ground. Any one wire that enters without that connection means all protection is compromised.

    For example, cable TV has no protector. It must make a low impedance (ie 'less than 3 meter') connection to single point earth ground. Best protection has no protector.

    Telephone and AC electric cannot connect directly. So that low impedance (ie 'less than 3 meter' - it is that critical) is made via a 'whole house' protector.

    The antenna must also have its own short as possible connection to earth.

    Earth lightning rods to protect the building. Earth incoming cables to protect appliances. Early 20th Century ham operators would disconnect their antennas. Even put antenna leads in mason jars. And still suffered damage. Damage stopped when they finally earthed the antenna lead. Disconnecting is a least effective solution. You must earth a surge before it can even enter the building.
  9. westom


    Nov 25, 2009
    100 years of well proven science. Read a case study of how a Nebraska radio station stopped having damage. Notice the only item always addressed to have direct strikes, routinely, without damage:

    Even protectors are only as effective as the low impedance connection to (and every word has major significance) single point earth ground.
  10. bud--

    New Member

    Jun 13, 2012
    Excellent information on surges and surge protection is at:
    - "How to protect your house and its contents from lightning: IEEE guide for surge protection of equipment connected to AC power and communication circuits" published by the IEEE in 2005 (the IEEE is a major organization of electrical and electronic engineers).
    And also:!.pdf
    - "NIST recommended practice guide: Surges Happen!: how to protect the appliances in your home" published by the US National Institute of Standards and Technology in 2001

    The IEEE surge guide is aimed at people with some technical background.

    The code just requires a ground block that allows the coax shield to be earthed.

    Best is no protector? The IEEE guide says “there is no requirement to limit the voltage developed between the core and the sheath. .... The only voltage limit is the breakdown of the F connectors, typically ~2–4 kV.” And "there is obviously the possibility of damage to TV tuners and cable modems from the very high voltages that can be developed, especially from nearby lightning."

    Any grounding for a TV antenna is not intended to protect from a direct lightning strike. Much more elaborate protection would be required. And separate ground rods are looking for trouble, even if they are bonded to the house earthing system.

    The antenna is not likely to have large surge currents, like cable and phone can have. IMHO the best protection is to have the antenna coax enter the house near the power service, and connect the entry ground block with a short wire to a common connection point on the power earthing system. Cable and phone entry protectors should also connect with short wires. Using too long a wire is shown in the IEEE surge guide starting page 30.

    If a strong surge is earthed, the "ground" system in the house can rise thousands of volts above 'absolute' earth potential. Much of the protection is that all wiring rises together. That requires short entry protector ground wires.

    Plug-in protectors do not work primarily by earthing a surge. As explained in the IEEE surge guide (starting page 30) they work by limiting the voltage from each wire (power and signal) to the ground at the protector.

    If using a plug-in protector all interconnected equipment needs to be connected to the same protector. External connections, like coax also must go through the protector.

    Turning a TV "off" does not actually turn off the power off unless you have a real old TV. Turning the TV off would not likely change damage.

    If lightning "touches" the antenna you have real big problems.

    For commercial broadcast, the antennas, feed lines, and other equipment, have extensive protection for lightning. Hams with high antennas are real likely to have good protection.

    For protection from a direct strike, a house would need lightning rods. The system can also protect the TV antenna
  11. Wendy


    Mar 24, 2008

    AAC is a no flame zone. It is possible to argue your case civilly and you will do so. I have moderated several comments that violate this basic policy. They will will be review by the moderating staff. Parts of some or possibly all will remain moderated after we decide. We will get back with you.
  12. atferrari

    AAC Fanatic!

    Jan 6, 2004
    Antennas from the vessels' radio stations were routinely disconected when not in use no matter what the forecast said.

    My most impressive personal experience with lightnings was while on watch at the bridge of a vessel crossing from Ushuaia to Antartica.

    The lighting struck on starboard side of the foremast just 80 meters ahead of the bridge creating a blinding and incredibly thick light vein running from the top to main deck, accompanied by a terrible noise like of an explosion.

    The surprise, the light and the noise level disconcerted me for maybe a minute. Now, I can imagine the effect of those explosives used by SWAT groups but I always wonder how they protect themselves from them.
  13. westom


    Nov 25, 2009
    Venues that must always work and never suffer damage do not disconnect. Each suffers direct lightning strikes. And continues operations uninterrupted.

    Occurs 23 times annually to electronics atop the Empire State Building. Happened 40 times annually to electronics atop the WTC. Direct strikes without damage are so routine that the damage is considered human created failure.

    Protection is never about a protector. Protection is always about what effective protectors connect to: single point earth ground.

    Orange County FL suffered repeat failures to their Emergency Response system. So they wasted no money on plug-in protectors. A case study demonstrates how all protection is implemented so that Orange County never disconnects during any thunderstorm:

    A surge selects appliances that make a best and destructive connection to earth. Either a surge connects harmlessly to earth without entering the building. Or damage results. Multiple case studies did what the IEEE, NIST, US military, FAA, ARRL, etc all recommend. Protection is not about the protector. Protection is always about the earth ground.

    Anyone who thinks a wire through a protector or UPS is protection, essentially, is educated by advertising myths. Manufacturer specs do not claim that protection. Therefore nobody will post manufacturer specs. Protection means a surge current is not inside; not hunting for earth destructively via appliances. If inside, that current simply blows through a protector. Nothing stops a hunt for earth. A protector adjacent to any appliance will somehow stop or absorb that energy? Impossible.

    AC electric may be three incoming wires. Do all three connect that short to earth? If not, then protection is only rumored.

    A fact stated repeatedly by responsible organizations such as the NIST, IEEE, Motorola, Sun Microsystems, all telcos, and those many case studies. From the NIST (page 17), a protector missing its earth ground connection is "useless":
    Munitions dumps suffer direct lightning strikes without damage. Even their protector remains unharmed. Many solutions, now implemented in homes, were pioneered in munitions dumps: Ufer grounds.

    Your concern is a rare surge - maybe once every seven years - that can overwhelm existing and superior protection. Any facility that cannot have damage upgrades earthing to exceed code requirements. And connects every incoming wire 'low impedance' to that single point earth ground. Either directly for best protection. Or via a 'whole house' protector.

    A protector is only as effective as its earth ground. A critically important low impedance (ie 'less than 10 foot', no sharp wire bends, etc) connection. A 'whole house' protector (even sold in Lowes and Home Depot) is sized to earth direct lightning strikes without failure. And costs about $1 per protected appliance.
  14. Wendy


    Mar 24, 2008
    The only appliances I have ever suffered damage from lightning were those that didn't have a surge suppressors. This is real world experience. They work even on an ungrounded setup such as an old garage door opener. One size does not fit all. You must match solutions to circumstances that vary widely.

    I am not going to be sucked into this thread except for this one post, but I know how to suppress lightning strikes for antennas, most HAMs do. I have build antenna systems that I know took repeated hits with no damage elsewhere in the setup. I never needed it, but some large commercial antennas do use specialty MOVs. They work, and the systems are designed by experts.

    Then there is magnitudes of difference in lightning, there are bolts rated as super bolts, that are much bigger than conventional bolts. You did mention them. They are rare, but they happen. Even the best protections can fail if one hits.

    To answer the OPs question, as this has drifted a bit off topic for his use, I would both unplug the power and antenna if you are concerned. It would be nice if the house is up to modern code, with a good third wire ground. I would also use surge suppressors, if they get burned out they are cheaper than the appliances. In the real world however, most people don't bother to unplug anything, depending on the surge suppressors and luck. A lot of fancy surge suppressors supposedly insure the electronics they are protecting. Never tested the theory myself (never had to), but it is something to keep in mind.

    Westom: You have several statements that I find off, mostly around surge suppressors in general where practical experience suggests otherwise. I have a few appliances that are not grounded where a surge suppressor made a difference. You are missing whole technologies for large antenna farms involving MOVs. I do not argue your main discussion, but you are missing on a few points.
    Last edited: Jul 9, 2012
  15. westom


    Nov 25, 2009
    So what protected a dishwasher, bathroom GFCIs, furnace, smoke detectors, door bell, refrigerator, etc? For your logic to work, then every device not on a protector must have been destroyed.

    Same logic also proved electric wires caused childhood leukemia. He also eliminated data that did not agree with his conclusions. His deception was discovered years later proving that electricity was not causing childhood leukemia. He also ignored data that contradicted the conclusion.

    Elementary school science demonstrated how myths are created. Spontaneous reproduction: a dry lake suddenly had life when filled with water. Or moldy bread breeds maggots. Both myths proven by observation. Both violated what science always requires to have knowledge. 100 years of well proven science also says an adjacent device called a protector is not effective. A completely different device, also called a protector, is effective because it connects to earth. Yes, two completely different devices share a common name.

    Engineers traced surge damage when a powered off computer was connected to an adjacent protector. That protector bypassed protection inside the power supply. Earthed a surge destructively through the computer. We confirmed our conclusion (based in years of engineering knowledge) by also replacing every damaged semiconductor in the surge path. All computers worked fine for years.

    Or view that protector's numeric specifications. Where does it claim protection that observation only assumes? It doesn't. Observation that contradicts manufacturer specs is somehow valid? Why do you know it does something that even the manufacturer will not claim?

    Conclusions, only from observation, are classic junk science. As taught even in elementary school science. Junior high science says knowledge requires two things. First a hypothesis based in well proven concepts. Second, experimental evidence that demonstrates the hypothesis quantitatively. Your observations provide neither.

    Well proven science says why adjacent protectors are near zero protection. But again, I have done this stuff as an engineer for many decades. Have seen adjacent protectors make damage easier. Some have even witnessed a house fire created by the adjacent protector.

    Read the Nebraska radio station case study. Naive station engineers literally made damage easier by using observation and assumption. A solution began by using well proven science. By restoring what does protection - earth ground. What did they not install? No 'adjacent to appliance' protectors.

    What do telcos do to have maybe 100 surges with each storm? And no damage? No protectors adjacent to electronics. Superior protection means up to 50 meter *separation* between protector and electronics. Why do I know this with numbers?

    Telcos want every protector connected 'low impedance' to earth. In your case, low impedance means 'less than 10 feet', no sharp bends in the ground wire, wire not inside metallic conduit, no splices, ground wire separated from all other non-grounding wires, etc. All concepts based in well understood engineering principles. All requirements that a protector 'adjacent to electronics' violates.

    In most cases, an appliance protects itself - such as the dishwasher, air conditioner, clock radios, stove, furnace, smoke detectors, washing machine, CFL bulbs, etc. Or did all those have invisible protectors? Reality: those appliances probably protected themselves.

    Read the case studies. Or learn why the NIST uses the word "useless". "The best surge protection in the world can be useless if grounding is not done properly."

    Why do they earth 'whole house' protectors in munitions dumps? And not use adjacent protectors? People could die. An earthed protector is that effective. But again, a protector is only as effective as its earth ground. Those who truly know protection spend most time worrying about the earthing - not protectors.

    Again, for the OP: Early 20th Century hams would suffer damage. Even disconnect the antenna. Put that antenna lead in a mason jar. And still suffered damage. Damage stopped when an antenna lead was earthed. Disconnecting has always been an unreliable protection solution. Especially when destructive surges occur even when thunderstorms are not present.

    In facilities that cannot have damage, they never disconnect.
  16. strantor

    AAC Fanatic!

    Oct 3, 2010
    My house in the Philippines only had type A plugs, no 3rd pin ground. I would suspect that Lightfire's house is the same, although the website I linked to says that the Philippines uses Type A, B, and C, I never saw types B & C. Also I was surprised to read on that site that the mains voltage is 240VAC, 60Hz. I thought for sure it was 120V, but then the only USA devices I ever plugged in were my laptop and cellphone charger, everything else was local stuff, so I never blew anything up to find out.
  17. bud--

    New Member

    Jun 13, 2012
    Westom believes that surge protection must directly earth a surge. Thus plug-in protectors, which are not well earthed, can not possibly work.

    The IEEE surge guide explains (starting page 30) how plug-in protectors work. It is not primarily by earthing the surge, earthing occurs elsewhere. Plug in protectors work by limiting the voltage from each wire to the ground at the protector. The voltage between the wires going to the protected equipment is safe for the protected equipment.

    Westom is fond of links like this, which has a 280 ft lightning rod (aka tower antenna).
    Hams with antennas that are likely to be struck by lightning have much more complicated protection than the rest of us need.

    If you want to protect your house from a direct lightning strike you need lightning rods.

    Both the IEEE and NIST must have been "educated by advertising myths".
    Both say plug-in protectors are effective.


    Some plug-in protectors even have protected equipment warranties.


    Many people have posted specs for westom. He always just ignores them.

    Protectors do not work by "stopping" or "absorbing".

    The IEEE surge guide explains how plug-in protectors work.
    Ignored by westom. Just like he ignores anything that does not fit his limited view of protection.


    Immediately following westom's quote is a list of surge protectors that can be used.
    Number 6 is "Plug-in...The easiest of all for anyone to do. The only question is 'Which to choose?'"

    What else does the NIST surge guide says about plug-in protectors?
    They are "the easiest solution".
    And "one effective solution is to have the consumer install" a multiport plug-in suppressor.

    Airplanes regularly get hit by lightning.
    Are they crashing?
    Do they drag an earthing chain?

    Service panel protectors are a real good idea.
    But from the NIST guide:
    "Q - Will a surge protector installed at the service entrance be sufficient for the whole house?
    A - There are two answers to than question: Yes for one-link appliances [electronic equipment], No for two-link appliances [equipment connected to power AND phone or cable or....]. Since most homes today have some kind of two-link appliances, the prudent answer to the question would be NO - but that does not mean that a surge protector installed at the service entrance is useless."

    Service panel suppressors do not by themselves prevent high voltages from developing between power and phone/cable/... wires. The NIST surge guide suggests that most equipment damage is from high voltage between power and signal wires. (An example of where a service panel protector would provide no protection is the IEEE surge guide example starting page 30.)

    An investigation by the author of the NIST surge guide found the maximum surge with any reasonable probability of occurring is 10,000A per service wire. The IEEE surge guide has a reference to it. That is based on a 100,000A strike to a utility pole adjacent to the house in typical urban overhead distribution. Only 5% of strikes are stronger, and the strike is very close.

    Service panel protectors with much higher ratings are readily available. High ratings mean long life. Service panel protectors are very likely to protect anything connected only to power wires from a very near very strong lightning strike. They may or may not protect equipment that has both power and signal connections.
  18. bud--

    New Member

    Jun 13, 2012
    The author of the NIST surge guide investigated how much energy might be absorbed in a MOV in a plug-in protector. Branch circuits were 10M and longer, and the surge on incoming power wires was up to 10,000A (the maximum that has any reasonable probability of occurring). The maximum energy at the MOV was a surprisingly small 35 joules. In 13 of 15 cases it was 1 joule or less. That is also true for GFCIs and other devices.

    There are 2 reasons the energy is so small. For a strong surge, at about 6,000V there is arc over [US] from the service panel busbars to the enclosure. When the arc is established the voltage is hundreds of volts. Since the enclosure connects to the earthing system that dumps most of the surge energy to earth. And the impedance of the branch circuits to the relatively high frequency (short duration) surge currents mean not much surge current (and energy) can reach equipment connected to the power wires.

    Any competent manufacturer will say what I did in my first post:
    "All interconnected equipment needs to be connected to the same protector. External connections, like coax also must go through the protector."

    Any competent user will RTFM.

    Any competent engineer can figure out how plug-in protectors work.

    Complete nonsense, repeated.

    Well proven science shows the energy at a plug-in protector is not likely higher than 35J, and most likely under 1J.

    Any protector in the US should be listed under UL1449. To pass a protector has to survive a series of test surges and remain intact. That at least gives a floor of protection. Protectors with far higher ratings are readily available.

    What does the NIST surge guide really say about plug-in protectors?
    "The easiest of all for anyone to do. The only question is 'Which to choose?'"
    "The easiest solution".
    And "one effective solution is to have the consumer install" a multiport plug-in suppressor.

    It appears to be a religious belief (immune from challenge). Westom ignores anything that conflicts with that belief.

    But westom is evangelical in his belief and compulsively googles for "surge" to save the universe from the scourge of plug-in protectors.

    For real science read the IEEE and NIST surge guides. Excellent and reliable information on surges and surge protection. And both say plug-in protectors are effective.

    Then read the sources that agree with westom that plug-in protectors do NOT work. There are none.
    strantor and Wendy like this.