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  • Drifter
    Junior Member
    • Apr 2015
    • 5

    Negative wires to inverter

    I have 3 strings of panels that each will be going to their own inverter. They are all grounded with copper to the grounding post buried into the ground. My question is can I pig tail the ground of the three strings into one and take it down to a bus bar and then plug the 3 invertors negative wire into the bus bar? Its a 50' run from panels to inverters and I would like to only run 1 50' line for the negative as opposed to spending a lot more on 150' of wire.

    Thanks

    Nick
  • foo1bar
    Solar Fanatic
    • Aug 2014
    • 1833

    #2
    Originally posted by Drifter
    I have 3 strings of panels that each will be going to their own inverter. They are all grounded with copper to the grounding post buried into the ground. My question is can I pig tail the ground of the three strings into one and take it down to a bus bar and then plug the 3 invertors negative wire into the bus bar? Its a 50' run from panels to inverters and I would like to only run 1 50' line for the negative as opposed to spending a lot more on 150' of wire.

    Thanks

    Nick
    Possibly - but now that 50' line needs to be sized for the higher current (bigger wire - more expense) - and you need to have the wires come together (extra junction - more expense) and junction for the wires to split to go to the inverters (more expense)

    Once you do that, does it make sense to do it? I don't know - that's something you'll have to figure out.

    BTW - are you sure you're going to have it grounded? It seems like all the inverters I looked at were "ungrounded" systems (EGC only - no GEC and no tie to ground on DC wire)

    Comment

    • Drifter
      Junior Member
      • Apr 2015
      • 5

      #3
      Originally posted by foo1bar
      Possibly - but now that 50' line needs to be sized for the higher current (bigger wire - more expense) - and you need to have the wires come together (extra junction - more expense) and junction for the wires to split to go to the inverters (more expense)

      Once you do that, does it make sense to do it? I don't know - that's something you'll have to figure out.

      BTW - are you sure you're going to have it grounded? It seems like all the inverters I looked at were "ungrounded" systems (EGC only - no GEC and no tie to ground on DC wire)

      I have pig tails that will allow me to put the 3 negative wires together. The hot wires are still individual lines, its just the negative wires (so I would be running 4 lines instead of 6). There shouldn't be any current in the negative line, but either way I am using 10awg wire so it would take the voltage (up to 600V at least). And the split I would be doing at the inverter would be a simple bus bar with 3 negative wires to each of the 3 inverters. Cost would be a couple of bucks.

      True, the inverters themselves do not have a ground to earth. but the panels and frames are grounded to earth.

      Thanks for your comments and food for thought.

      Comment

      • sensij
        Solar Fanatic
        • Sep 2014
        • 5074

        #4
        Originally posted by Drifter
        There shouldn't be any current in the negative line, but either way I am using 10awg wire so it would take the voltage (up to 600V at least).
        Whoa, slow down. If you really believe that no current goes through the negative, you had better stop now and find some help. How big are the strings, and what type of panel? What model inverter?
        CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

        Comment

        • Wy_White_Wolf
          Solar Fanatic
          • Oct 2011
          • 1179

          #5
          Originally posted by Drifter
          I...There shouldn't be any current in the negative line, but either way I am using 10awg wire so it would take the voltage (up to 600V at least)....
          Electricity need a complete circuit. The amperage in single negitive cable would be the total of the 3 positve cables and needs to be sized accordingly.

          WWW

          Comment

          • Sunking
            Solar Fanatic
            • Feb 2010
            • 23301

            #6
            Originally posted by Drifter
            I There shouldn't be any current in the negative line,
            You have no business working with electricity because you have no idea of how it works or what you are doing.
            MSEE, PE

            Comment

            • foo1bar
              Solar Fanatic
              • Aug 2014
              • 1833

              #7
              Originally posted by Drifter
              either way I am using 10awg wire so it would take the voltage (up to 600V at least).
              Not voltage - current. And AWG doesn't matter for voltage. You REALLY need someone to help you with this - you don't know enough to know where your knowledge is incomplete.

              And the split I would be doing at the inverter would be a simple bus bar with 3 negative wires to each of the 3 inverters. Cost would be a couple of bucks.
              Cost would be $15-$20 for the splice at each end. The splice has to be wet-rated since it's outdoors (even if it's inside a box) and those are $15-20.

              Originally posted by Drifter
              True, the inverters themselves do not have a ground to earth. but the panels and frames are grounded to earth.
              .
              An inverter without an EGC? Um... No.
              You really don't know what you're doing - you need to learn a LOT more or hire someone to do at least the design work for you and check it.

              You now have 3 people telling you to get someone with more experience with electricity.
              I seriously hope you take that advice.

              Comment

              • Drifter
                Junior Member
                • Apr 2015
                • 5

                #8
                Originally posted by foo1bar
                Not voltage - current. And AWG doesn't matter for voltage. You REALLY need someone to help you with this - you don't know enough to know where your knowledge is incomplete.


                Cost would be $15-$20 for the splice at each end. The splice has to be wet-rated since it's outdoors (even if it's inside a box) and those are $15-20.


                An inverter without an EGC? Um... No.
                You really don't know what you're doing - you need to learn a LOT more or hire someone to do at least the design work for you and check it.

                You now have 3 people telling you to get someone with more experience with electricity.
                I seriously hope you take that advice.
                Yes, all the above is mostly true which is why I was here asking questions. And I do appreciate the responses.

                Comment

                • Sunking
                  Solar Fanatic
                  • Feb 2010
                  • 23301

                  #9
                  Originally posted by Drifter
                  Yes, all the above is mostly true which is why I was here asking questions. And I do appreciate the responses.
                  There is no possible way for you to learn how to DIY. It takes electricians 5 to 7 years to be able to do this. Not a chance in hell you can do this.
                  MSEE, PE

                  Comment

                  • Drifter
                    Junior Member
                    • Apr 2015
                    • 5

                    #10
                    Originally posted by Sunking
                    There is no possible way for you to learn how to DIY. It takes electricians 5 to 7 years to be able to do this. Not a chance in hell you can do this.
                    Yeah. Thanks for all the support. Never did get an answer to my questions. My words were twisted around and I was shown to be stupid, but hey, you guys are smarter than me and have been so helpful.

                    Comment

                    • foo1bar
                      Solar Fanatic
                      • Aug 2014
                      • 1833

                      #11
                      Originally posted by Drifter
                      Never did get an answer to my questions.
                      I gave you a straight answer to your question. Can you combine them - possibly.
                      The other question that I answered that you *didn't* ask but should have is "Should I combine them?" and the answer is very very likely "No, it doesn't make sense to do that."

                      BTW the responses to your question were actually fairly polite for this forum - there are a number of posters on this forum who are not tactful.
                      I can't control what they post though - all I can do is try to be polite myself and hope they do the same.

                      Comment

                      • Sunking
                        Solar Fanatic
                        • Feb 2010
                        • 23301

                        #12
                        Drifter the problem is you do not know even one basic fundamental of electricity. For me that is all I need to know, you cannot be helped as you cannot comprehend what you have already been told. I will prove my point. Answer one very simple question you have to know inside and out to do this.

                        What is 690?

                        If you cannot answer that question in full detail and cite quotes, no one can help you or should even try. You are going to get yourself killed or burn down your home and I am not going to be part of it. If you do not like that, then tough.
                        MSEE, PE

                        Comment

                        • Drifter
                          Junior Member
                          • Apr 2015
                          • 5

                          #13
                          Originally posted by foo1bar
                          I gave you a straight answer to your question. Can you combine them - possibly.
                          The other question that I answered that you *didn't* ask but should have is "Should I combine them?" and the answer is very very likely "No, it doesn't make sense to do that."

                          BTW the responses to your question were actually fairly polite for this forum - there are a number of posters on this forum who are not tactful.
                          I can't control what they post though - all I can do is try to be polite myself and hope they do the same.
                          Foo1 thank you. I have been working with wiring boats for years, including very large boats. When using shore power you hook the neg to a bus bar inside the panel box and the main to the fuse line. When working on small boats I place a bus bar under the dash and run a single feed to the bus bar under the dash and a fuse box also under the dash. I do the same at the rear of the boat. This eliminates the mass of unknown wires running the length of the boat. This is my first, but not my last solar setup and I was wondering if I could do the same that has always been done on every house wiring that uses a bus in the main panel. On everyone of my installs I have had an electrician look them over to make sure i didn't forget anything. I plan on doing the same with this setup. It was just a simple question looking for a simple answer. Can I eliminate wires by using the bus. Some have questioned the cost. I have the solar approved harnesses that bring three panels in to one to be used in parallel wiring that were $8 a piece, which I already have surplus. This would eliminate 100' of cable ($100). The ones that think I am going to burn the house down or there is no way to ever do it myself don't need to assist me. I accept that and support their right to do that. This site clearly does not support us DYI types, but we did invent the computer, the car, the electric car, and the solar industry which these people are so protective.

                          Again Foo, thank you for the help. I do appreciate it.

                          Comment

                          • sensij
                            Solar Fanatic
                            • Sep 2014
                            • 5074

                            #14
                            I asked some questions which are necessary to give you proper help. No answers?
                            CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

                            Comment

                            • Mike90250
                              Moderator
                              • May 2009
                              • 16020

                              #15
                              Originally posted by Drifter
                              I have 3 strings of panels that each will be going to their own inverter. They are all grounded with copper to the grounding post buried into the ground. My question is can I pig tail the ground of the three strings into one and take it down to a bus bar and then plug the 3 invertors negative wire into the bus bar? Its a 50' run from panels to inverters and I would like to only run 1 50' line for the negative as opposed to spending a lot more on 150' of wire.
                              Thanks Nick
                              The Answer is NO. This is not right, and is not safe. You need to either hire an electrician/solar contractor to do this, or abandon it for 2 years to take some electricity and solar install courses.

                              We cannot teach over the internet, and you need lots of coaching.

                              For different questions, please start a new thread. This is closed.
                              Last edited by Mike90250; 04-17-2015, 07:54 PM.
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