I am in the process of replacing my submersible well pump( single phase, 220v, 4 wires from pump). At my wellhead the electrical connection is as follows I have two hot lines one common and a bare ground. My question(s) begin here, at some point it seems that the 220v at well head turns to 120v 10-2 wire which is of course run to my safety shut off(30amp breaker) then to my pressure switch both of these only having 3 wires a hot a common and a bare ground. According to the diagram on the inside cover of this control box I am going to be short one wire unless I install at the wellhead and I'm uncertain of the water proof capabilities of the control box so I would really rather connect this where my shut off, pressure switch and pressure tank is located. diagram of system with control boxThank you in advance for any help provided it will be greatly appreciated.inside cover of control box

  • Is your pump motor (pump cable) a 2-wire or a 3-wire type? Aug 19, 2018 at 12:48
  • There are 4 wires total from the pump, 2 hot leads 1connects to control box and the ground. I only have 3 wires at the well head and into the house 1 hot lead 1 common and 1 ground.
    – Greg R.
    Aug 19, 2018 at 13:45
  • I’m confused where the 120v mention comes into play? Was the old pump 120v, and the new 240v, or are you calling the wiring 120v because the wire colors are black and white? Is the breaker for the pump a single or double pole?
    – Tyson
    Aug 19, 2018 at 15:12
  • RE: Tyson.. Sorry for the confusion, that was my mistake. The breaker is a 30amp double pole breaker. At this point I guess my question has narrowed a bit as I have gathered info from here and there. I think my question now is would I tie the 2 hot leads together onto one and connect the motor control from the pump to my common? Then carry that all the way through the remainder of my connections?
    – Greg R.
    Aug 19, 2018 at 15:25
  • Hello, and welcome to Stack Exchange. It would be helpful if you edited your comments' content into the original question, so that future generations can better understand it. Aug 20, 2018 at 14:19

2 Answers 2


Put the control box in a box

If you're unsure about the water resistance abilities of your well pump control box, you can simply stick it inside a suitably sized NEMA 3R rated enclosure securely mounted at the wellhead, with the cables routed in to the outer box through knockouts in the bottom and a small drain hole drilled in the bottom to equalize pressure and let condensation exit.


It looks like the pump is actually a 220 volt 2 phase with a capacitor start. So you have 2 hot wires and the start winding and the ground wire coming up from the pump. The best scenario is if the pressure switch is a 2 pole switch so both phases get Deenergized. However, you could wire a single pole pressure switch in line with the pump to get it to work but in doing so leaves a hot wire connected which is unsafe. The start winding circuit has a centrifugal switch in line inside the pump which disconnects the start winding once it gets up to speed.

So the power gets connected to the pressure switch and when the pressure drops then it connects power to the pump at the point labelled battery socket.

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