Noob grounding question

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  • northerner
    northerner Solar Expert Posts: 492 ✭✭✭✭✭✭
    #32
    Re: Noob grounding question
    Cariboocoot wrote: »
    Before I completely give up I'll just remind anyone reading this thread that electrical safety ground procedures are not meant to handle the effects of lightning/stray Voltage and vice-versa.

    So rather than trying to work a solution that is code compliant with the NEC, it's best to setup your grounding that works best to safe guard against stray lightning surges (providing you live in an area subject to frequent electrical storms).

    It would be great if both electrical safety and lightning protection could be accomplished with one setup, but sounds like that compromise can't be made?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #33
    Re: Noob grounding question
    northerner wrote: »
    So rather than trying to work a solution that is code compliant with the NEC, it's best to setup your grounding that works best to safe guard against stray lightning surges (providing you live in an area subject to frequent electrical storms).

    It would be great if both electrical safety and lightning protection could be accomplished with one setup, but sounds like that compromise can't be made?

    Not unless you can successfully argue the point with John Wiles. ;)
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  • northerner
    northerner Solar Expert Posts: 492 ✭✭✭✭✭✭
    #34
    Re: Noob grounding question
    Cariboocoot wrote: »
    Not unless you can successfully argue the point with John Wiles. ;)

    I have no intention doing that. ;) I will do what is safest for my system however.
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  • DanS26
    DanS26 Solar Expert Posts: 269 ✭✭✭
    #35
    Re: Noob grounding question
    northerner wrote: »
    I have no intention doing that. ;) I will do what is safest for my system however.

    If you are really intent on setting up a sparking gap, then you may want to research the lightning protection used by millions of farmers on their electric fence lines. Instead of the spark gap this device may be better:

    http://www.zarebasystems.com/store/electric-fence-accessories/ala-z

    Dan
    23.16kW Kyocera panels; 2 Fronius 7.5kW inverters; Nyle hot water; Steffes ETS; Great Lakes RO; Generac 10kW w/ATS, TED Pro System monitoring
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  • northerner
    northerner Solar Expert Posts: 492 ✭✭✭✭✭✭
    #36
    Re: Noob grounding question
    DanS26 wrote: »
    If you are really intent on setting up a sparking gap, then you may want to research the lightning protection used by millions of farmers on their electric fence lines. Instead of the spark gap this device may be better:

    http://www.zarebasystems.com/store/electric-fence-accessories/ala-z

    Dan

    Thanks for that Dan! It may be an option for someone intent on running their panel ground inside as required by NEC.

    Another option, if you do run the array ground inside, is to physically disconnect the array ground to the ground bus inside the house, prior to an intense electrical storm. That is obsessive I know, but we had one storm last year that was SCARY and lasted much of the night. The surge arrestor at the combiner box, should have the ground wire connection straight down to the ground rod (ie the shortest route to ground), and not to the ground connection (ie bus bar in the combiner box) that runs inside, for best protection.
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #37
    Re: Noob grounding question
    DanS26 wrote: »

    IMHO lightning rods and grounding rods do not attract strikes.
    There is a common misunderstanding about lightning rods, i.e. that they attract lightning strikes. This is not true; their purpose is to bleed off local electrical potential in an effort to prevent a strike.
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  • NorthGuy
    NorthGuy Solar Expert Posts: 1,913 ✭✭
    #38
    Re: Noob grounding question
    ggunn wrote: »
    There is a common misunderstanding about lightning rods, i.e. that they attract lightning strikes. This is not true; their purpose is to bleed off local electrical potential in an effort to prevent a strike.

    If you stick it high enough it surely will attract lightning. High towers are more likely to be struck by lightning that small ones.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #39
    Re: Noob grounding question
    ggunn wrote: »
    There is a common misunderstanding about lightning rods, i.e. that they attract lightning strikes. This is not true; their purpose is to bleed off local electrical potential in an effort to prevent a strike.

    Yes!
    If they actually attracted strikes they'd be useless as the lightning would turn the whole system into a melted mess of useless scrap metal. :D
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  • northerner
    northerner Solar Expert Posts: 492 ✭✭✭✭✭✭
    #40
    Re: Noob grounding question

    Lightning rods do not attract lightning strikes as previously stated, but they do provide a safer route to ground in the event of a strike. They divert the strike to ground which will prevent damage to other property which could otherwise be damaged if not present.

    http://science.howstuffworks.com/nature/natural-disasters/lightning7.htm

    I just noticed there is a company that makes lightning rods that are lightning suppression systems which actually prevent lightning from striking. They aren't cheap however!

    http://www.diginfo.tv/v/12-0087-n-en.php
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  • northerner
    northerner Solar Expert Posts: 492 ✭✭✭✭✭✭
    #41
    Re: Noob grounding question
    Cariboocoot wrote: »
    Yes!
    If they actually attracted strikes they'd be useless as the lightning would turn the whole system into a melted mess of useless scrap metal. :D

    Hey, there's plenty of value in scrap metal these days.;) Evident when you hear about metal thieves pulling out live wires for the copper! Sometimes it doesn't turn out well for them.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,622 admin
    #42
    Re: Noob grounding question

    Interesting on the second link...

    I guess that they are putting a static charge generator at the top of the tower and reverse charging it (make top of tower less potential to the clouds)?

    I thought that you can have lightning with different polarity under the cloud base... Hmm:
    Lightning polarity: Positive or negative, depending on the direction of current flow between the cloud and ground; negative (95% of cases) when current flows from cloud to ground, positive (5%) when ground to cloud.

    Wonder if they have the ability to reverse the charge on their "anti lightning rod"?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • NorthGuy
    NorthGuy Solar Expert Posts: 1,913 ✭✭
    #43
    Re: Noob grounding question
    Cariboocoot wrote: »
    Yes!
    If they actually attracted strikes they'd be useless as the lightning would turn the whole system into a melted mess of useless scrap metal. :D

    You should expect them to attract lightning because the resistence of the metal that the lightning rod is made of is much lower than the resistance of the surrounding air.

    A number of people as far back as in 18-th century - Thomas François D'Alibard and Georg Wilhelm Richmann - were able to use a lightning rod to attract lightning.

    Here is the research of lighnigs and high towers. They say that 95% of the lightning strikes hit the tip of the tower, and only 5% hit the tower below the tip. In my mind this means that the tip attracts the lightnings strikes.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #44
    Re: Noob grounding question

    Gee, I seemed to be something of a lightning rod myself. :p
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #45
    Re: Noob grounding question
    NorthGuy wrote: »
    If you stick it high enough it surely will attract lightning. High towers are more likely to be struck by lightning that small ones.
    The theory behind lightning rods is that their very sharp points bend the electrostatic lines of potential so sharply that they get crammed very close together which results in the breakdown of the dielectric (insulating) properties of the air. This allows charge to flow more freely and dissipate before the difference in potential gets high enough to cause a strike. Reference "St. Elmo's Fire".
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