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  • 230V irrigation pump wiring

    I am installing a 1-1/2 HP pump (exterior installation) to my underground sprinkling system. The current draw is 6 amps at 230v and the pump will be approximately 10 feet away from the load center. I plan to use a 15 amp double pole breaker, and #14 wire in conduit.

    There are only three terminals on the pump - L1, L2 and GND. The L1 & L2 terminals are the hot terminals. I was going to code one of the hot wires with red electrical tape at each end.

    Should I install a grounding rod outside at the pump?
    Last edited by khe; 05-12-2009, 12:47 PM.

  • #2
    Re: 230V irrigation pump wiring

    In a 240 volt application (except for dryers and ovens where there is also a need for a single 120 v application like a light or clock), there are two hots and a ground. If you are using 14-3, you have two hots (red and black) the neutral (white) and the bare copper (ground) wires. You would use the red and the black and the bare goes to the ground terminal. You do NOT use the white in that application. Clip it at both ends and leave it in the shielding. You could also use the 14-2 that you mentioned since your current draw is so small. Personally, I'd use the 12-2 w/gr. just because, I tend to overbuild and like the extra margin of safety the 12 gauge offers. But if it is really only a 6-amp draw, the 14-2 or 14-3 with a 15 amp breaker is more than adequate. If you use the 14-2 then the white is recoded as red, either with tape or a Sharpie marker. I prefer the Sharpie's. They're quicker and won't get worn off. You can also recode it any color other than green and still be OK (i.e. orange, yellow, purple, etc. if you have those colors in tape or Sharpie available.) Is your panel that you're connecting to properly grounded?
    Adding an additional ground rod at the point of the appliance is a no-no since you can initiate a feedback loop which you do not want to do. There are specific grounding requirements for panels and subpanels that are clearly spelled out in the NEC and that said, grounding is one of the most misunderstood (even amongst electricians and inspectors) of all circuit designs.
    Cheers,
    Jim Don

    Comment


    • #3
      Re: 230V irrigation pump wiring

      Originally posted by JimDon View Post
      In a 240 volt application (except for dryers and ovens where there is also a need for a single 120 v application like a light or clock), there are two hots and a ground. If you are using 14-3, you have two hots (red and black) the neutral (white) and the bare copper (ground) wires. You would use the red and the black and the bare goes to the ground terminal. You do NOT use the white in that application. Clip it at both ends and leave it in the shielding. You could also use the 14-2 that you mentioned since your current draw is so small. Personally, I'd use the 12-2 w/gr. just because, I tend to overbuild and like the extra margin of safety the 12 gauge offers. But if it is really only a 6-amp draw, the 14-2 or 14-3 with a 15 amp breaker is more than adequate. If you use the 14-2 then the white is recoded as red, either with tape or a Sharpie marker. I prefer the Sharpie's. They're quicker and won't get worn off. You can also recode it any color other than green and still be OK (i.e. orange, yellow, purple, etc. if you have those colors in tape or Sharpie available.) Is your panel that you're connecting to properly grounded?
      Adding an additional ground rod at the point of the appliance is a no-no since you can initiate a feedback loop which you do not want to do. There are specific grounding requirements for panels and subpanels that are clearly spelled out in the NEC and that said, grounding is one of the most misunderstood (even amongst electricians and inspectors) of all circuit designs.
      Cheers,
      Jim Don
      From his description, I figured he would rather run conduit all the way to the motor, rather than the romex jockey approach. In which case, I'm going to assume you just have black and green THWN, you don't HAVE to mark the ungrounded conductors, especially since it's 240 volt single phase. This isn't a three phase system where phase rotation is an issue. But if you wish, there is nothing stopping you.

      As for the ground rod, you do not need one as JD said, the grounding conductor from the motor to the panel should be sufficent. The only time I have ever driven a supplemental ground rod was for back-up generators and pump motors for pools.

      As always, local codes apply. If the AHJ wants one, he gets it.
      Last edited by tailgunner; 05-12-2009, 09:05 PM.

      Comment


      • #4
        Re: 230V irrigation pump wiring

        I got the well in and am in the process of hooking up the pump. The pump is rated 8.5 amps at 230 volts. I hooked it up temporarily to test the gallons per minute of my well and while it was running, I measured the current draw with my Amprobe. The pump draws 6 amps running but 20 amps when it starts up (momentary spike).

        Am I still OK to use a 15A breaker and 14 gauge wire since the 20 amps is a momentary surge only at startup?

        Comment


        • #5
          Re: 230V irrigation pump wiring

          Yes,
          Minor spike on startup is normal with a motor. Put your Amprobe with a splitter on your frig some time and see what the current draw is for that compressor. Those breakers have a slow trip feature to them to accommodate the draw on start up. Otherwise, homes would have breakers tripping everytime an air conditioner, frig, furnace, etc. started up. If that's the most amps your drawing, you have nothing to worry about.
          BTW, Good Job.
          Cheers,
          Jim Don

          Comment


          • #6
            Re: 230V irrigation pump wiring

            That's what I figured but only want to do the job one time. Thanks!

            Comment


            • #7
              Re: 230V irrigation pump wiring

              I have a question. Does he need a two pole 15 GFCI breaker for that application?

              Comment


              • #8
                Re: 230V irrigation pump wiring

                If he is wiring it for 240 volts, he does.

                Comment


                • #9
                  Re: 230V irrigation pump wiring

                  Originally posted by jbfan View Post
                  If he is wiring it for 240 volts, he does.
                  I may be wrong but I think he was inquiring about the GFCI part.

                  Comment


                  • #10
                    Re: 230V irrigation pump wiring

                    Originally posted by gusty60 View Post
                    I may be wrong but I think he was inquiring about the GFCI part.
                    ^^^
                    What he said.

                    Comment


                    • #11
                      Re: 230V irrigation pump wiring

                      Originally posted by jbfan View Post
                      If he is wiring it for 240 volts, he does.
                      No. He does not need a gfci breaker to feed this pump, unless the manufacturer requires it.


                      I need to pay closer attention to the details!

                      Comment


                      • #12
                        Re: 230V irrigation pump wiring

                        JB,
                        That's OK. But your post sure sent me running back to Sec. 430 to check on that item and do a refresher course on that section. Man oh man, but that is a confusing section. Almost as much fun as grounding and neutral readings. LOL
                        Cheers,
                        Jim Don

                        Comment


                        • #13
                          Re: 230V irrigation pump wiring

                          Hey guys, not sure if this applies in your area but there was new code that came out in Ontario (Canada) around 2006 that required the ground wire to be larger than the feed wires for deep wells. I am not an electrician so I don't have the code handy. My well was wired this way, the electrician and inspector told me something about ground has to be one size larger than the feed.

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