I'm attempting to reconnect an outdoor irrigation pump and I'm unsure which wires should connect to which terminals (labeled L1 and L2) in the pressure switch. The pump is a Myers HJ100S and the power is supplied by a 20A/250V three-prong plug with white, red, black, and bare copper wires.

Here is an image showing the setup. On my pump the connector on the left is labeled L1 and the one on the right is labeled L2.

Manual image

I know where the grounding wire connects, but I'm not used to working with 240V. I believe that black and red are hot and white is neutral. Which wire(s) should be connected to each terminal?

  • 1
    does your wiring diagram or instructions show a neutral, white wire, connection?
    – JACK
    Jun 16, 2020 at 20:23
  • The instructions (which I downloaded, the pump is old) only say "Attach the incoming power leads to the two outer screws on the pressure switch as shown in Figure 8."
    – sbooth
    Jun 16, 2020 at 20:28
  • Wow... a black and white photo. Bringin' the art to Home Improvement! :D
    – FreeMan
    Jun 17, 2020 at 13:05

1 Answer 1


The two power leads would be your black wire and your red wire. they'd go to your L1 and L2. The white wire, neutral is probably only used if running the pump at 120V.

  • Thanks for the response. Does it matter which goes to L1 and which to L2? I assume I just cap the neutral with a wire nut?
    – sbooth
    Jun 16, 2020 at 20:41
  • 1
    Nope. Yes, cap the neutral. Stay safe out there.
    – JACK
    Jun 16, 2020 at 20:45

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