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Thread: Possible lightning strike on outside power box causing damage

  1. #1
    DIY Junior Member mcdgary's Avatar
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    Default Possible lightning strike on outside power box causing damage

    This concerns 220V-240V deep well pump. Located at a 100 year old farm house. A 12/2 (two hot wire, no ground) wire runs from an elecrtical box inside the house to the well pump about 80' away outside. The 12/2 wire is connected to power box on a 4x4 pressure treated pole; the box is about 6' up the pole from the ground. Each wire (line) runs thru a 25 amp screw in type breaker to form the "load" terminals. The two wires then go down to the start run capacitor. Since no one lives there I take the "male" part of the start run capacitor off (one stolen taught me a lesson) and pull the lever to "off" on the electrical box upon leaving. Also, I unplug the two large 60 amp breakers on the main control panel inside the house. Hence, after I leave there is no electrical path from the house panel to the box on the pole, there is no path from the pole box to the "female" start run capacitor.

    Upon returning in July I found the metal door on the outside control box "blown" off. Inside the house the metal door to the main power box was "blown" open. THere are four 20 or 25 amp screw in type fuses, which serve as the circuit breakers for minor house wiring and output to the pump. One of the fuses was disintegrated and blown out of the box (the brass part of the fuse was still screwed in.)

    My theory is that during a severe thunder storm lightning "found" the 4x4 pole and metal box at the top of the pole. Since there is no path to the start run capacitor and, hence, the well (which I suppose is the pump's "ground" it jumped from the metal box to one of the "lines" of the 12/2 inside the metal control box and went (reversely) back to the mainbox in the house and POP! went the fuse.

    Since I had no tools or meters (I was down for a funeral) I could not check much. I did have a small multi-meter and verified the two 110v inside aftering correcting the disintegrated 25 amp fuse, but nothing at the 4x4 pole box.

    (1) Is my theory probably correct?
    (2) Is there any problem of connecting a 12 gauge solid copper wire to the metal box on the 4x4 pole and running the wire down to a long metal rod into the ground about 2' deep? This wire is completely independent to the main wiring and comes into play to provide a lightning path to ground since I attempt to comletely de-activate all electrical paths when I'm not using the pump?
    (3) I've had the power company to turn power off so I can get to the backside of the old power panel.

  2. #2
    Porky Cutter,MGWC Porky's Avatar
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    You're probably right "Lightning" with a direct hit. Replace all the known damaged parts then try the pump. If it works you're OK. If not the pump motor will probably have to be replaced. In your area I'd try Noland of Ferguson but keep in mind that almost none of them know nothing about pumps.

    When lightning hits directly nothing is going to help however there should be a ground wire running from the control box, fuse box and pressure switch to the well motor case in the well. The well motor case is the best ground, even better than a ground rod.

    I live in Virginia Beach!
    Porky Cutter, MGWC
    (Master Ground Water Consultant)

  3. #3
    DIYer, not in the trades LLigetfa's Avatar
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    Lightning most likely entered from the service mains. If it had hit the pole by the well, most likely there would be nothing left and all the wiring to the house and down the well would have fried.

    Opening breakers and lifting the capacitor may stop smaller surges but a close powerful strike having traveled miles through the air won't be stopped by a mere inch gap.

    Minimum code for grounding is two 8 foot ground rods which cannot dissipate the energy of a lightning hit. It usually won't even sink enough current to trip your mains (at mains voltage, not lightning). I think a 200 amp service needs #4 gauge to the ground rods.

    If the well casing is metal, it could be bonded to the service ground using at least #6 gauge wire. Many older pumps didn't have a ground wire but if it did, it alone could not sink enough current. It is the collective of the utility ground, service ground, grounded casing, and grounded pump that gives you any chance of surviving a nearby lightning hit but probably not a direct hit.

    I worked for the PoCo where we were grounding high tension lattice towers and would put in as many as 50 ground rods per tower. You should see the elaborate grounding around telecom towers.

  4. #4
    DIY Junior Member mcdgary's Avatar
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    Default Thanks, very good reply

    Name:  FuseBox.jpg
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Size:  10.2 KB
    Can you suggest how maybe lightning got into my fuse box? From the outside I assume the utility power line there are two 115V (hots), a neutral and a ground, which come into the Power Company's meter. Inside the house are two service main and since I always pull the two large breakers (there are two carteridge fuses (60 amp) one each breaker there is no path to the four (2 on each side and below) screw-in 25 amp fuses, thus no power to any house circuit including the lines to the well pump. The phot looks similar to my control panel.

    Quote Originally Posted by LLigetfa View Post
    Lightning most likely entered from the service mains. If it had hit the pole by the well, most likely there would be nothing left and all the wiring to the house and down the well would have fried.

    Opening breakers and lifting the capacitor may stop smaller surges but a close powerful strike having traveled miles through the air won't be stopped by a mere inch gap.

    Minimum code for grounding is two 8 foot ground rods which cannot dissipate the energy of a lightning hit. It usually won't even sink enough current to trip your mains (at mains voltage, not lightning). I think a 200 amp service needs #4 gauge to the ground rods.

    If the well casing is metal, it could be bonded to the service ground using at least #6 gauge wire. Many older pumps didn't have a ground wire but if it did, it alone could not sink enough current. It is the collective of the utility ground, service ground, grounded casing, and grounded pump that gives you any chance of surviving a nearby lightning hit but probably not a direct hit.

    I worked for the PoCo where we were grounding high tension lattice towers and would put in as many as 50 ground rods per tower. You should see the elaborate grounding around telecom towers.

  5. #5
    DIYer, not in the trades LLigetfa's Avatar
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    Quote Originally Posted by mcdgary View Post
    Can you suggest how maybe lightning got into my fuse box?
    I already surmised that. Pulling the fuses creates only a small air gap which is nothing for lightning that has traveled through miles of air gap. Of course you have the advantage of seeing all the evidence.

    Quote Originally Posted by LLigetfa View Post
    Lightning most likely entered from the service mains. If it had hit the pole by the well, most likely there would be nothing left and all the wiring to the house and down the well would have fried.

    Opening breakers and lifting the capacitor may stop smaller surges but a close powerful strike having traveled miles through the air won't be stopped by a mere inch gap.
    Is there any evidence of the lightning directly hitting the pole by the well? I have seen the damage a direct hit can do... splintered wood poles, exploded concrete, fused metal, melted insulation the full length of the wire that shunted the lightning, etc..

  6. #6
    DIY Junior Member mcdgary's Avatar
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    The metal door about the size of a paperback book cover was missing on the pole's power connect box. No other physical damage was visible. Vandals could have torn the door off. No one had entered the old farm house (I do keep it locked.) When I went to insert the two main breakers is when I found one of the circuit fuses (round screw in) blown from it brass receptible. Since the mains were out I screwd the brass receptible out inserted a good fuse and had regular power except a "no-go" at the well. Bought me a cheap multi-meter (had 3 good ones at my VA home, but none at GA farm.) Nothing on either wire of the 12/2 cable, which is mostly underground. Under both mains at what I guessed were the two wires of the 12/2 I got 110V and 110V and 220 across both. At the other end (the outside post) at the well, nothing, i.e., zero volts. When I get back down and with the power cut off by Georgia Power I'm going to hook a 6V lantern battery at the inside house end of the 12/2 and check the well end out side to check for continuity, or connect the two ends together inside the house and check resistance at the well.

    How is lightning prevented from any of the 3 wires from the utility input, can it come inside on either the hots or neutral or ground?

  7. #7
    DIYer, not in the trades LLigetfa's Avatar
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    Quote Originally Posted by mcdgary View Post
    ...can it come inside on either the hots or neutral or ground?
    It can enter on any or all of the above. The ground rods cannot absorb all of the energy and the well represents a better ground than the rods at the panel so it follows the path to ground. If the wire from the house to the control box is fried, it stands to reason that lightning ran down those wires. The wires from the control box to the pump and the pump itself are also probably fried.

  8. #8
    DIY Junior Member mcdgary's Avatar
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    Name:  FarmHouse.jpg
Views: 186
Size:  84.1 KB A picture of my Georgia farmhouse.

    In 1975 a severe thunderstorm came in over the James River (I live in Newport News, VA); we were warned by TV and radio of its severity. I have an ancient Blackgum tree in the center of my front yard about 10' from the house. Wife and two little ones and I hunkered down in the kitchen to wait it out. The old Blackgum tree has been hit more than once before this. I'm leaning against the Electric stove. Lightning hit hard, and found the old Blackgum again. The house rumbled and I was shocked by the stove absorbing part of the bolt. A "Head Boat" (a boat that takes people out fishing on the Chesapeake Bay) did not make it back into a safe harbor that day in time causing the loss of several lives, including the Captain.

    Since there was no damage on the pole, and the control box had been removed leaving no direct path to the well casing I've got my fingers crossed.
    Last edited by mcdgary; 09-17-2012 at 06:13 PM. Reason: Position of photo

  9. #9
    DIY Junior Member mcdgary's Avatar
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    Default Yep, we're VA neighbors

    If the pump is damaged I'll just have to go with a local recommendation in the Georgia area; pumps of this type are very practical for such a rural area.

    I live inNewport News.

    Quote Originally Posted by Porky View Post
    You're probably right "Lightning" with a direct hit. Replace all the known damaged parts then try the pump. If it works you're OK. If not the pump motor will probably have to be replaced. In your area I'd try Noland of Ferguson but keep in mind that almost none of them know nothing about pumps.

    When lightning hits directly nothing is going to help however there should be a ground wire running from the control box, fuse box and pressure switch to the well motor case in the well. The well motor case is the best ground, even better than a ground rod.

    I live in Virginia Beach!

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