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Lightning rod missing on building

Discussion in 'Electrical Engineering' started by Skybuck Flying, Jun 6, 2011.

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  1. Hello,

    Today there was a thunderstorm and a lot of rain.

    I went to the back of my appartment and I noticed the lightning rod on the
    other building is missing.

    I am 100% sure there used to be a lightning rod there. I have pictures to
    prove it too.

    So I have some theories why the lightning rod is missing:

    1. It was stolen by a copper thief.
    2. It was wrecked by a cat (unlikely).
    3. It was removed by the owner of the building.
    4. It was stolen by aliens for fuel :)

    It seems most likely that it was human intention to remove it.

    Now the question is why was it removed ?

    Again a few theories come to mind:

    1. To make profit from copper.
    2. To make the situation more safe.
    3. To make the situation more dangerous, and perhaps trigger a fire or
    lightning strike.

    I am now unsure what to think of this I will sketch the situation though, so
    I do not have to provide a picture.

    The situation was as follows:

    (First time I attempt ascii art in windows live mail):

    +--------------+
    | |
    | |
    +------+ | |
    | | | |
    | | | |

    In case it doesn't come through properly:

    ..|
    ..|
    ..|
    ||
    ||

    So there are two buildings.

    The lower building had a lightning rod as well.

    This lightning rod is now removed.

    So the question is:

    Is it safer to remove lightning rods from lower buildings so the higher
    building catches the lightning ?!?

    Perhaps this is done so that the lightning does not split into my window
    which is near the lightning rod... if I happen to be standing there.

    Or perhaps now it will I don’t know...

    Perhaps it's also in some kind of guide line or law how to apply lightning
    rods...

    Make me think a little bit of "empire state building in new york"... it
    probably catches the most lightning if not all ?!?

    Bye,
    Skybuck.
     
  2. Orac

    Orac Guest



    Jeetje!
     
  3. Too late, the cat's dead.
     
  4. Ken

    Ken Guest

    Example
    http://www.hvi.uu.se/Lightning/bilder/bild3t.gif
     
  5. Rich Grise

    Rich Grise Guest

    You missed 5: It took a direct hit and vaporized or just melted and
    slumped over to where you can't see it.

    Hope This Helps!
    Rich
     
  6. Rich Grise

    Rich Grise Guest

    Of course it's dead! Nobody's fed or watered the damn thing in 75 years!

    ;-)
    Rich
     
  7. "Rich Grise" wrote in message
    "
    You missed 5: It took a direct hit and vaporized or just melted and
    slumped over to where you can't see it.
    "

    If it melted then there should be something visible shouldn't there be ? ;)

    Perhaps the top section was not connected to the bottom section and
    therefore it was removed but I doubt it.

    I will tell you what is left over:

    A slightly blue trace on the wall... probably "copper rust"

    Does copper turn into a blue substance ?!?

    If not then it might have been something else.

    Bye,
    Skybuck.
     
  8. Guest

    While the initial ionization will certainly start through the path
    with lowest resistance, but when the actual massive current starts
    flowing, you have to consider also the inductance.

    The longer paths usually have bends, in which the inductance is much
    higher, causing a large voltage gradient. This gradient can cause a
    flashover to a nearby grounded object and the main part of the current
    peak is redirected that way (i.e. it takes the shortest path).

    For instance in one church, the lighting conductor was running about
    30 cm above the roof, then making two sharp bends and then running
    vertically down at 30 cm distance from the wall into a proper
    grounding electrode. The high gradient due to the bends caused a
    flashover through the roof into the internal electric wiring, causing
    considerable damage inside. There was an article with a few pictures
    in Wireless World a few decades ago.
     
  9. Seum

    Seum Guest

    Acid rain on copper will leave a green color.
     
  10. Uwe Hercksen

    Uwe Hercksen Guest

    Hello,

    they often use other metalls than copper for lightning rods.

    Bye
     


  11. I figured it was because the cat got struck by lightning...
     
  12. Don Kelly

    Don Kelly Guest

    Agreed with the high E field outside the bend but wasn't the church inside
    the bends?

    2 sharp bends - can't be 90 degrees but surely sum must be 90 degrees
    (assuming the over roof conductor was parallel to ground). The proximity of
    the internal wiring and other metallic material (eavestrough, metal fascia,
    etc) at some point near the roof could be a factor as well. One can also
    consider that there can be reflection effects with fast front waves that
    have caused "backflash" at the top of transmission line towers when there
    is a strike to the shield wire. (down tower inductance is also involved ).
    This would also be related to your comment about inductance of a bend- which
    would become important in the case of fast front waves.

    Possibly "shortest path" should be the "electrically shortest path"- least
    impedance- not the physically shortest path.
    With lightning, this path may be quite different than expected so all design
    is based on probability and crossed fingers. I have known of a case of
    lightning striking near a building- blowing out wiring in the building then
    ploughing a furrow across a farmyard to take out some other equipment. The
    ground rod nearest to the strike point was ignored.

    Don Kelly
    cross out to reply


    "Phil Hobbs" wrote in message
    Bends in conductors cause huge E field enhancements at the outside of
    the bend.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal
    ElectroOptical Innovations
    55 Orchard Rd
    Briarcliff Manor NY 10510
    845-480-2058

    email: hobbs (atsign) electrooptical (period) net
    http://electrooptical.net
     
  13. Guest

    I have seen lots of old historical buildings, with the conductor
    follows the roof, the roof extends beyond the wall, the conductor
    makes a 90-150 turn to go around the edge of the roof, continues
    horizontally towards the wall and then bends 90 degrees to go down
    vertically along the wall :).
     
  14. Don Kelly

    Don Kelly Guest

    "Androcles" wrote in message

    | Agreed with the high E field outside the bend but wasn't the church inside
    | the bends?

    Dogleg, Don. Chicane if you prefer.
    http://en.wikipedia.org/wiki/Dogleg

    | 2 sharp bends - can't be 90 degrees but surely sum must be 90 degrees
    | (assuming the over roof conductor was parallel to ground).

    Dogleg sums to 180 degrees.
    Down the spire, across the roof, down the wall: dogleg.
    ----------------------
    Since the original message didn't mention a spire- somewhat important
    information- I did not assume one.
    There are a number of churches in my vicinity- none have spires. However, I
    did pass (a few days and 1000 miles away) an Orthodox church which had
    several to spare.:)

    Don Kelly
    cross out to reply
     
  15. Don Kelly

    Don Kelly Guest

    "Benj" wrote in message

    Don is right. Lightning is known to do extremely strange things when
    striking buildings/the ground/trees/people/etc. Mostly you try to
    provide paths to grounds (lightening rods) and hope for the best.
    Still any protection is better than none. The lightning rod was
    invented by Benjamin Franklin because of the constant burning of barns
    from lightning strikes. The "lightning rod salesman" has been a staple
    of rural culture for much of the 20th century. The missing rod and
    cable is probably due to "copper thieves". Electric companies have
    been having huge problems with these thieves stealing ground wires
    from systems to sell the copper. They don't care about the dangers
    that this creates. In fact they just don't care period. A church near
    me recently had a brand new $20,000 air conditioner stripped of all
    copper (probably worth maybe $35). But also one of the functions of
    lightning rods is to alter the sky-ground E field gradients. By doing
    so you can alter the equipotential map such that lightning will tend
    to strike in places other than your buildings (places of higher
    gradients). I forget the values but the gradients can be quite high
    something like hundreds of volts per meter? Maybe Don knows more.
    ------------------------------
    1)Overhead ground wires (for lightning protection) are generally steel,
    sometimes ACSR (aluminum cable steel reinforced) For calculation of the
    characteristic impedance of such wires, an effective radius of 15cm is often
    used to account for corona. typically Z=60*ln 2h/r where h is the height
    from ground (horizontal wire). Actual conductor resistance is a minor issue
    2) Fair weather atmospheric E fields of 100-300v/m are not uncommon. During
    storms, fields near ground could be in the 50+KV/m range even if there are
    no strikes nearby. Much higher fields have been measured in clouds.
    Actually the rod will raise the E field above it - tending to make it a
    better target. Corona might effectively lengthen the rod and increase its
    diameter which would tend to limit gradients. There have been arguments
    that rods tend to reduce local gradients by bleeding off atmospheric charges
    (looky- they produce corona flares when a storm approaches) and at least one
    "protection scheme" was based on that. In general this concept has received
    little credence. The rod as target philosophy is still the general basis of
    design.
    3) as for the inductance of a down conductor- while it has an effect, in the
    cases where backflash (from struck shield to phase conductor) is a factor
    on transmission lines - tower inductance would make a difference for fast
    front waves -say, rising to peak well under a microsecond -the average is
    about 1.5 microseconds. Quite often the tower is treated as a cylinder
    and wave reflections rather than inductances are considered.
    This could be done with building protection- use strike distance design to
    eliminate direct strokes above a tolerable level and then consider an
    average stroke and the T-line surge models with regard to reflections. Throw
    in lightning statistics and come up with what gives a reasonable probability
    of such backflash. Add several ounces of Bougerre' factors cross fingers
    and squat, not lie, on the ground.

    Note:, it has been about 20 years since I was involved in this and it was
    for transmission line design (much based on EPRI's EHV reference book and
    other sources which I do not have at present) and only considered building
    protection in passing- so I have a lot of rust accumulated.


    Don Kelly
    cross out to reply
     
  16. Please don't "shout" it makes it hard to read ! ;) :)

    "The Ghost In The Machine" wrote in message

    GO WEATHER A THUNDERSTORM, IT'LL ALL COME BACK TO YOU REFRESHED.
    JUST STAY IN THE CLEAR CENTER AND AVOID STANDING TALLER THAN WHATS
    UNDER THE DARK NEBULAS......OR ELSE MY ADVICE TO Y'ALL IS CLIMATICALLY
    VOIDED
    BOOWAHAHAHAHA.......WE R WEATHERING ONE RIGHT NOW.
    YOU DOONKOFFZ ARE GOOD FOR NOTHING..WE COULD BE SETTING UP AN ARRESTOR
    ARRAY LIKE NEVER SEEN BEFORE IN THE HISTORY OF THE WEATHER CHANNEL.
    TEEHEEHEE ....DAMMIT!
    TGITM
    PATECUM
     
  17. Are you trying to give me eye cancer ? ;) :)

    I don't read most of your shit, because it looks like shit.

    So it's pretty pointless for you to post, at least for me.

    Perhaps there are many others who find your capital nonsense unpleasent to
    read.

    Didn't they teach you anything in school ?! ;) =D

    Bye,
    Skybuck.


    "Michael A.Terrell" wrote in message

    YOU MUST BE IN A DIFFERENT DIMENSION...
    IN THIS ONE IT IS EASIER TO READ.....THIS DOESNT MEANS YOURE COOL,
    FOOL.
    AND STOP TRYING TO TELL ME HOW TO POST, YOU TROLLING FLYBOY.
    MR. PATECUM
    TGITM CO. INC.
    BOOWAHAHAHAHAHAHA
    WOAH HOBOHOHOHOHO
    AHHHHHAHAHAHAHAHAHAHAHA
    LEAVE IN SYMPATHY.....I KNOW WHATCHA DID, TERRELL.
     
  18. The doctor would tell me to put you on ignore is that what you want ? ;)

    Bye,
    Skybuck :)

    "The Ghost In The Machine" wrote in message

    GO SEE A DOCTOR ABOUT THAT CANCER.
    SIGHHHHH.....THOUGH YOUR CRAP IS RANK & TOTALLY OFF TOPIC, PLEASE COME
    BACK WHEN YOURE READY TO DISCUSS LIGHTNING ARRESTERS AGAIN.......AND
    **** SCHOOL! :-/ IT DID NOTHING FOR YOU.
    PATECUM
    TGITM
     
  19. Windows Live Mail should get an auto-text-beautifier just for ghosties like
    this ghostie... :)

    Bye,
    Skyghost ! ;) =D

    Where's pacman when you need him ?! ;) =D

    "The Ghost In The Machine" wrote in message

    WHO ARE YOU RESPONDING TO MICHELLE?
    AND WHAT THE **** ARE YOU SAYING FOOL?
    OHHHHH, NOW I SEE, ITS FLYING FUCKTARD....YOUR GAY LITTLE ANTICS HAS
    FINALLY LANDED YOU A NICE BOYFRIEND...I HOPE YOU FIND THE GAY
    HAPPINESS YOU DESERVE IN EACH OTHERS ASS.
    IT'S PATECUM ......NOT PATTYCAKES...YOU FREAKY DICK JOCKEY.
    TGITM
     
  20. Don Kelly

    Don Kelly Guest

    "Michael Moroney" wrote in message

    How could I be anti-ghost? I have never seen a ghost and I have never
    communicated with one, either. Just a pretender.
    ---------------------------------
    Please, Michael, don't feed it. When you do, you publicize its puerile
    rants- which I don't get directly because I kill filed it long ago.


    Don Kelly
    cross out to reply
     
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