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Thread: Welder Ground Lead

  1. #61
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    Quote Originally Posted by jaggedben View Post
    I think the more general point is that lightning currents are not comparable to welding currents in either behavior or duration. It does not follow that the welding currents are safe because lightning currents may, in the odd circumstance, travel over the same metal without causing damage. And of course, sometimes lightning on EGCs does cause damage.
    that wasnt the point, and i dont think anyone was stating such.

    the point was, LPS is to be tied to GEC. ok, which also means its tied to EGC. ok, and some say it doesnt matter that its tied to EGC because like dumping a buck of water in sink it all goes down the drain, except one minor fact, GEC also has ohms, which means a % of the LPS amps also runs over EGC to wherever, hence why i said LPS systems should really be isolated from the wiring of a structure. but, isolation is not ez w/ lightning.

    i think iron structures, the iron is the GEC and not EGC, so they can clamp a beam near the welder and then run out 100ft (or whatever) to stick weld, etc.

    as for welding amps on EGC (one leg of the welder), that can be an issue depending on how the EGC stuff is deployed/connected. however, a burn hole in MC might be amps taking a new route, and it created a haz point on the MC and it eventually melts, which can obviously cause an issue for the wires inside.

  2. #62
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    Quote Originally Posted by FionaZuppa View Post
    the point was, LPS is to be tied to GEC. ok, which also means its tied to EGC. ok, and some say it doesnt matter that its tied to EGC because like dumping a buck of water in sink it all goes down the drain, except one minor fact, GEC also has ohms, which means a % of the LPS amps also runs over EGC to wherever, hence why i said LPS systems should really be isolated from the wiring of a structure. but, isolation is not ez w/ lightning.
    A drain is the only way out. Nothing says there is only one drain. The bigger the drain (the better the connection and path to Earth) the more amps it gets.

    A LPS is not going to have a connection/path to Earth on one side of the building only. That would expose the EGC on the other side and make it carry the brunt of the strikes on that side. The LPS will shunt/shield and take the brunt of the strike. Like the bumper on a car takes the worst so the passengers can survive.
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  3. #63
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    Quote Originally Posted by FionaZuppa View Post
    hence why i said LPS systems should really be isolated from the wiring of a structure. but, isolation is not ez w/ lightning.
    Do you have evidence to support that isolating the LPS rather than bonding is a better solution?
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  4. #64
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    Quote Originally Posted by mivey View Post
    Do you have evidence to support that isolating the LPS rather than bonding is a better solution?
    are you really asking this question???

    IEC 62305

    Let's take a look in slow motion at what a typical 100 kA lightning current can do by induced coupling to a panel or similar. Bear in mind, this is an induced (secondary) effect and not even the full directly connected lightning current itself.


    Last edited by FionaZuppa; 12-05-17 at 08:28 AM.

  5. #65
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    just because its in NFPA books doesnt always mean thats the right/best way !!


  6. #66
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    Quote Originally Posted by FionaZuppa View Post
    are you really asking this question???
    Well, yes. Yes I am.
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  7. #67
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    Quote Originally Posted by FionaZuppa View Post
    just because its in NFPA books doesnt always mean thats the right/best way ...
    It's not just the nfpa, although they're pretty reliable, Motorola's R56 standard doesn't have Anything isolated.
    If you don't think too good, don't think too much.

  8. #68
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    Quote Originally Posted by ActionDave View Post
    It's not just the nfpa, although they're pretty reliable, Motorola's R56 standard doesn't have Anything isolated.
    seems to be varying views on the subject of isolated vs non-isolated LPS then........
    i am in the isolation camp.

    i think we see it bonded to gec only because the LPS is typically not an isolated one, hence its better to tie it to gec to keep it in a metal path.

    isolated LPS is also magnitudes harder to do for say the Empire State Building (or the like).

  9. #69
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    Quote Originally Posted by FionaZuppa View Post
    did i miss something. doesnt the EGC have to tie to the GEC at some point?
    once tied, 4 million volts travels everywhere, everything has some ohms
    Quote Originally Posted by FionaZuppa View Post
    ...the point was, LPS is to be tied to GEC.
    ...
    which means a % of the LPS amps also runs over EGC to wherever, hence why i said LPS systems should really be isolated from the wiring of a structure. but, isolation is not ez w/ lightning.
    Quote Originally Posted by mivey View Post
    Do you have evidence to support that isolating the LPS rather than bonding is a better solution?

    Quote Originally Posted by FionaZuppa View Post
    are you really asking this question???

    IEC 62305

    The isolation IEC 62305 is talking about is using a shielding scheme, like you would see at a power substation. The isolation does not mean not connected to the electrical system as you have proposed. It is still bonded.
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  10. #70
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    Quote Originally Posted by FionaZuppa View Post
    isolated LPS is also magnitudes harder to do for say the Empire State Building (or the like).
    Shielding depends on the shield being the tallest thing around so there is the rub with isolating the ESB.

    That said, you can still cover a tall building and have lightning electrodes installed taller than stuff on the roof (again, a problem for the ESB because of the very tall stuff on the roof, like attennas).
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