2 Properties Connecting to Submersible Well Pump

Discussion in 'Electrical Forum discussion & Blog' started by invisible-man, Oct 30, 2010.

  1. invisible-man

    invisible-man New Member

    Messages:
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    Location:
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    Hi,

    My and my neighbors property both share an Artesian well and can swop who's power connects to the well via a changeover switch at the well head (also has a central off position).....this is very useful as both are second homes and if one winterizes it allows the other to draw from the well if needed, we both have our own pressure switch and tank etc.

    The pump is 240v and has just 2 hot wires and no ground.......my question is that the top of the well head is metal on plastic casing which I wanted to ground (if recommended to do so).

    My options as I see it are:

    1/ connect to just one of the properties ground wire permently to the well head
    2/ connect to both properties ground wires permently to the well head (was not sure if 2 properties could have their ground wires linked together
    3/ connect the ground wires into a third set of poles of the changeover switch (as there is one set spare) making ground to the well head with what property is powering the well at that time........only trouble with this option is that when the changeover switch is in the off position, the well head will not be connected to ground which could be 70% of the time

    Hope I have made some sort of sense!

    Thanks
  2. Thatguy

    Thatguy Homeowner

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    Location:
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    Plastic is an electrical insulator. Is there a path from either hot wire to the metal on top of the plastic casing? Are the water pipes metal?

    If you want to ground it anyway, driving a ground rod at the well may be the best choice.

    In some areas there is so much current through the ground that proper grounding can be pretty tricky.
    Last edited: Oct 30, 2010
  3. jwelectric

    jwelectric Electrical Contractor/Instructor

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    Location:
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    Let’s look at this from the beginning.

    One well supplied from two different sources?????????????

    The well cap should have a nonmetallic chase to allow the pump conductors to pass and also seal the opening when installed.
    Unless there is some way that the cap can become energized then it would not require any bonding. Should you want it bonded anyhow then connecting the equipment grounding conductor that supplies the pump would sacrifice.

    This would ground the well cap as the definition of ground is earth but to drive a rod would serve no purpose at all. It would be useless. What he is looking for is to open the overcurrent device should a hot conductor come in contact with the metal well cap. Driving a ground rod at the well would not accomplish this.

    Using Ohm’s law and the requirement found in 250.56 of the NEC the most amperage that earth would allow would be 4.8 amps and this wouldn’t open the breaker or blow the fuse. E=IxR or 120 volts divided by 25 ohms. 250.56 mandates that should there not be at least 25 ohms of resistance on one rod that the one rod must be augmented by another electrode.

    There is nothing tricky about driving an eight foot rod in the ground. All that is required is the swing of a hammer.
    Therefore connecting something to earth is simple. Ground defined in the NEC is “the earth” and grounded or grounding is defined as connected or connecting to ground or to something that will conduct to ground. How do you get that doing this could be tricky????????????????
  4. Bob NH

    Bob NH In the Trades

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    Location:
    New Hampshire
    A problem that can arise with common equipment grounds connected to two services (Your Case 2) is that if the power company neutral is lost at one service, then the ground connecting the two services carries the unbalanced current from the service that has lost the connection to the power company neutral. That equipment ground could be as small as #12, or even #14 if the pump is on a 15 Amp circuit. If a #14 equipment ground carries all of the unbalanced current from a large service it could overheat the insulation of adjacent conductors in the cable or pipe and cause a serious short to ground, and possibly a fire if it is in a combustible area.

    Your Case 3 would avoid that problem and would probably comply with the code requirement that all conductors in a circuit be carried together.

    I don't see a problem wih the pump or well-head not connected to ground in the OFF position since the power would also be disconnected at that time.

    Another solution that would work is to put a 2-pole GFI breaker in each circuit and leave out the ground. Such breakers are sold to use with hot tubs and spas. The downside of such a setup is that a current leak in the pump that might not affect performance would nevertheless trip the GFI breaker, which would be a nuisance.
  5. Thatguy

    Thatguy Homeowner

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    If the cap and the ground local to the well were at the same potential because they were connected then a grounded user wouldn't be shocked. Both the cap and the local ground could be at some voltage as measured with respect to a distant ground but the user would still be safe.

    Search on
    cattle shock farmer "stray voltage" swimming pool
    and terms like that.
    In some cases the PoCo will not or can not fix the stray current problem.

    There was one reference that said that the NEC rules actually cause the problem by treating the ground as a sink; current goes in and never comes out. The problem is, it does come out.

    I'm just the messenger, Rock. I didn't write the NEC and I didn't invent electrons.
    Last edited: Oct 31, 2010
  6. invisible-man

    invisible-man New Member

    Messages:
    22
    Location:
    United Kingdom
    Thanks guys for all your inputs, I will most likely go with option 3 as it does not seem from your comments that the ground is too important, and does not seem so important if not grounded when in off position.......

    I know that wells are prone to lightning and was not too sure if the grounding would help or work against a lightning strike, this was one of my reasons for looking into this!
    Last edited: Oct 31, 2010
  7. Thatguy

    Thatguy Homeowner

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    Last edited: Nov 1, 2010
  8. ballvalve

    ballvalve General Engineering Contractor

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    there are a whole lot of golfers and hikers with no hair and hearing that would disagree with that.
  9. Thatguy

    Thatguy Homeowner

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    That's 'cause they were the highest point in the area.
    And if you stand next to a tree and the tree is struck, the sap is instantly vaporized and the steam throws out wood at high speed and you get to dig splinters out if you are still alive and conscious.

    The good news is that a current that strong generates an enormous magnetic field and electric field that probably temporarily scrambles the brains of any living things that have brains, so he, she or it has amnesia for the event.
    Last edited: Nov 1, 2010
  10. jwelectric

    jwelectric Electrical Contractor/Instructor

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    In order for current to flow there must be a complete path from one side of the source to the other.
    As to all this bull shirt without the “R” about current running into the ground and not coming back out is just that, the waste of a bull.

    If it were possible for current to run into the earth and not come out then connecting only one side of a battery to earth would make it go dead. It just aint gonna to happen
  11. ballvalve

    ballvalve General Engineering Contractor

    Messages:
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    Location:
    northfork, california

    Predicting lightening as striking the "high" guys is bad science. Lightening is very FICKLE and assumptions unsafe.
  12. Thatguy

    Thatguy Homeowner

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