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OT - Well pump ground wiring?

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  • OT - Well pump ground wiring?

    I am having a water well drilled and hired an electrician to do the wiring. The well pump requires 240V and I also wanted a couple 120V service outlets for future use. The run from the electric panel on my house to the well is about 300-350 feet. The diagram below shows what I got. The resistors indicate future loads -with the center one being the 240V well pump.

    My question: Is it proper to have two separate earth grounds in this installation or should a fourth wire (ground) be run from the service entrance box to the remote breaker box? I want to make sure the installation is safe.

  • #2
    Where is the pump controller and pressure tank located?
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    • #3
      You will need a separate (fourth) ground wire installed in addition to the neutral.
      Jim H.


      • #4
        That is not a safe setup in the drawing.

        Under normal conditions there should never be any current flowing through the grounding system.
        I'm an abstract poet and I didn't even think I was.


        • #5
          Originally posted by Evan
          Where is the pump controller and pressure tank located?
          Immediately adjacent (<6 feet) to the box on the left side of the diagram.


          • #6
            That is pretty much how we have ours ran for around 30 years now. The grounds are seperated in case of lightning strike and static build up. You don't want that following up the wires to the house pannel. Our pressure switch, tank, and pump control box are at the building and not by the pump. Only thing at the pump is just the 220v wire and a rod driven in the ground for the forth (green) wire.


            • #7
              Local codes vary. You need to check and see what they require to meet code.

              Having said that, around here it is required to have a fourth wire for chassis ground (there might be a more correct term for that but I cant think of it right now).

              Your electrician should know what is accepted in your area.

              Civil engineers build targets, Mechanical engineers build weapons.


              • #8
                I think there needs to be a green earth ground wire run. Around here the neutral is not grounded or bonded to the green earth buss bar except under certain conditions. The white is run to ground on the entrance side of the service from the power company.

                I have never understood why they are not bonded in the service panel since the white comes into the panel as an earth ground but that is the code here.
                It's only ink and paper


                • #9
                  it appears to be contrary to a number of articles, unless tehre are exceptions I could not track down quickly...... and I find no exception to the standard branch circuit rules for well pumps.

                  The most glaring item is the non-mention of local grounding of the equipment grounding conductor (green wire), if there even is one. Normally the ground wire would be run with the others, and might be locally bonded to a rod etc. The NEUTRAL generally would NOT be grounded at the load.

                  then the added ground bond for the neutral, which is not a standard feature. The neutral (groundED conductor) is bonded to ground only at one place, at the service.

                  This seems to meet the requirements for a local ground rod and connection to the groundING conductor, which I don't see shown

                  The lightning argument probably doesn't apply, since both wiring to a sub-panel in a separate building, and the distribution wires coming IN to the service are equally susceptible, and are all connected to the service (obviously)

                  A quick pass through article 225 (outside branch circuits) didn't turn up any exceptions for any purpose, and article 250-24 (a) doesn't seem to apply, as there is a single service box, not one for the building and one for the pump.

                  547-8 requires teh pump and casing to be grounded to the box, which isn't shown and may or may not be (but presumably is) actually done here.
                  2801 3147 6749 8779 4900 4900 4900

                  Keep eye on ball.
                  Hashim Khan

                  It's just a box of rain, I don't know who put it there.


                  • #10
                    IMHO, you should
                    -not have the ground at the well
                    -add a insulated wire for your neutral
                    -clearly mark/tape the wires to show black red and white.

                    I am not sure about exact details of code, but this is pretty close.


                    • #11
                      Is the well earth close to any animals..

                      They can easily be electrocuted by fault potentials dissipating through a radius from the earth spike.



                      • #12
                        Water well regulations.

                        The National codes on water wells were ammended back in the 90's to require a ground wire from the motor control box to the submersible pump motor. At that time the motor harness was changed to the 4 wire configuration. Submersible cable was changed to 4 wires and not too long thereafter the 3 wire configuration was dropped from production. Here in Texas regulations required that the wiring be upgraded the next time the well was serviced. I was slow to warm up to this change but I ultimately came to believe that it was better. In the legalistic society that we live in code compliance is best.
                        Byron Boucher
                        Burnet, TX


                        • #13
                          Thanks for all informative replies. I live in the country and there are no inspectors to satisfy - my only concern is safety.

                          Just got off the phone with the electrician and he assured me this is routine practice in the area and does not present a safety hazard. I've tried to run through fault scenarios that would cause a problem with the current setup and can't think of one that seems to be an issue - but I'm sure I haven't thought of everything.

                          The well isn't drilled yet - the wiring was done first - so there aren't any actual hook ups yet. The electrician was recommended by the driller so presumably he knows what he needs.

                          Boucher: You said you warmed up to the change - why is that? Is there a safety advantage?

                          Can someone give an example of a fault that would create a safety hazard with this configuration?

                          The trench is still open so I can add a fourth wire without too much trouble if needed - but right now I'm leaning towards not.


                          • #14
                            Originally posted by torchroadster
                            Can someone give an example of a fault that would create a safety hazard with this configuration?
                            Yes, I believe I can. For one, if your ground rod is hooked up the case grounds and is connected to the neutral also, and your neutral develops an "open" between the sub panel and the main panel, you will have the chassis of everything connected to it at the sub panel end energized with a potential to earth whenever any equipment is turned on.

                            Install the fourth conductor now while you can do so easily.

                            BTW, your electrician is not very knowledgeable. He is required to do installations that meet Code as it exists today, not as it was in the eighties.
                            Location: Saskatoon, Saskatchewan, Canada


                            • #15
                              Safety is the first concern but not the only issue.

                              You must run a separate ground wire. It is common for the ground stakes near the distribution panel to have high resistance to ground due to dry earth, corrosion etc. In that case the ground then becomes the one at the pumphouse with the only effective connection being the neutral.

                              Because of the long wire run and resulting resistance this will cause high neutral to true ground voltages at the main panel that are proportional to the amount of current being drawn. It will appear as a voltage drop on all the house circuits with the neutral and the system ground elevated above true ground. This will cause many electronic devices to either fail or operate erratically, including especially computers.
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