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  • Grounding new small system.

    Is it safe to use a metal garden hose faucet as a system ground? No way can i drive a grounding pole 5' deep in this soil. Was going to run awg4 from inverter lug to water pipe faucet. Maybe battery negative also?
    600W, 40A MPPT, 230AH FLA,24V Samlex 1500W

  • #2
    It used to be done, but then the water company found that electrolysis was eating up their pipes
    Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister

    Comment


    • #3
      What kind of soil? Start a hole, fill it with water, and drive the rod down. Pull the rod out, add water, drive deeper. As long as you don't hit stone, you should be able to get it in by hand... I've put in several this way, even through clay that takes a pickaxe to dig through.
      CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

      Comment


      • #4
        Hi Gdwats.

        There are multiple things one needs to understand here. First there are two parts to your grounding system, one is the Grounding Electrode (GE) and often called the Grounding Electrode System. Another part is the Ground Electrode Conductor (GEC) this what connects your equipment to the GE and usually is wire and often #6 but that is subject itself to its own code calculations. In the NEC 250.52 describes all of the code compliant GE's and 250.53 describes installation of them. 250.66 and 250.122 is about sizing the GEC.

        Another thing is what exactly are you grounding and why? For example are you grounding your roof top system as required under 2014 code to have a 690.47(D)? If so then I would suggest having a chat with your building department on what they require since 690.47(D) is simply so dang dangerous it was made optional in the 2017 code and many areas will grant exceptions to having a separate GE and just want you to tie your rails to the existing service GEC to have a single point ground. Mike Holt has a great video on this subject.

        If you have a ground mount then you are required to have a 690.47(D) for that and then you have to follow 250.52. If you have a sub-panel at that ground mount (assuming your inverters are located there or you are using micros) then it needs its own 250.52 GEC and don't forget the EGC you run back to the source of this feeder.

        There are details about each of these but as long as the details are met, the following are compliant GE's. Again, you need to read the details in both 250.52, 53, 66 and 122 prior to deciding what way to go.

        - 10' of water pipe
        - building steel.
        - concrete enclosed electrode
        - ground ring of wire
        - two 8' ground rods at least 6' apart. (can be one but too many restrictions - easier to just drive 2). Angles allowed for rocks - see details.
        - plate electrode.
        - other listed electrodes - have to be UL listed installed to manufactures specs.
        - other underground metal systems.

        No gas lines or aluminum allowed.

        Easiest way to drive ground rods is with a hammer drill. Rent one and you will see what a dramatic difference it makes. Only thing that stops them are rock shelves or large rocks it cannot push aside or break through. I live in some really bad soil conditions (hard adobe type mud mixed with granite and crazy number of rocks) and my 13yrd old helped me drive a number of the rods both 8 and 10' for my ground mounts - all you do is hold the hammer in place and let it do all the work.

        Again if this is on your roof - say to yourself - "I want a single point GEC for safety" and work from there.

        Comment


        • #5
          Originally posted by tyab View Post
          Hi Gdwats.

          There are multiple things one needs to understand here. First there are two parts to your grounding system, one is the Grounding Electrode (GE) and often called the Grounding Electrode System. Another part is the Ground Electrode Conductor (GEC) this what connects your equipment to the GE and usually is wire and often #6 but that is subject itself to its own code calculations. In the NEC 250.52 describes all of the code compliant GE's and 250.53 describes installation of them. 250.66 and 250.122 is about sizing the GEC.

          Another thing is what exactly are you grounding and why? For example are you grounding your roof top system as required under 2014 code to have a 690.47(D)? If so then I would suggest having a chat with your building department on what they require since 690.47(D) is simply so dang dangerous it was made optional in the 2017 code and many areas will grant exceptions to having a separate GE and just want you to tie your rails to the existing service GEC to have a single point ground. Mike Holt has a great video on this subject.

          If you have a ground mount then you are required to have a 690.47(D) for that and then you have to follow 250.52. If you have a sub-panel at that ground mount (assuming your inverters are located there or you are using micros) then it needs its own 250.52 GEC and don't forget the EGC you run back to the source of this feeder.

          There are details about each of these but as long as the details are met, the following are compliant GE's. Again, you need to read the details in both 250.52, 53, 66 and 122 prior to deciding what way to go.

          - 10' of water pipe
          - building steel.
          - concrete enclosed electrode
          - ground ring of wire
          - two 8' ground rods at least 6' apart. (can be one but too many restrictions - easier to just drive 2). Angles allowed for rocks - see details.
          - plate electrode.
          - other listed electrodes - have to be UL listed installed to manufactures specs.
          - other underground metal systems.

          No gas lines or aluminum allowed.

          Easiest way to drive ground rods is with a hammer drill. Rent one and you will see what a dramatic difference it makes. Only thing that stops them are rock shelves or large rocks it cannot push aside or break through. I live in some really bad soil conditions (hard adobe type mud mixed with granite and crazy number of rocks) and my 13yrd old helped me drive a number of the rods both 8 and 10' for my ground mounts - all you do is hold the hammer in place and let it do all the work.

          Again if this is on your roof - say to yourself - "I want a single point GEC for safety" and work from there.
          Well, that's a book full.
          I only have 6 x 100W panels on the ground in my back yard going to a 40A (max in 100V,1020W) controller, 225AH 24V FLA battery bank and a 1500W 24V AC inverter. This seems like a lot of trouble for a few hundred Watts, but I thought it best to ground things to one central grounding pole/block/plate and call it good. Yikes!
          600W, 40A MPPT, 230AH FLA,24V Samlex 1500W

          Comment


          • #6
            Are these too soft to drive in 5 ft?
            https://www.gmesupply.com/copper-cla...MaAv-JEALw_wcB
            600W, 40A MPPT, 230AH FLA,24V Samlex 1500W

            Comment


            • #7
              Originally posted by Gdwats View Post
              Are these too soft to drive in 5 ft?
              https://www.gmesupply.com/copper-cla...MaAv-JEALw_wcB
              No. That type will work. Remember it is Copper Clad and not totally made of copper so it is pretty stiff.

              Comment


              • #8
                Ok, many thanks. Is there any particular distance from the battery, cc and inverter that the rod should be?
                Every time I think I'm done asking questions, something new comes up. Thanks to folks here, I can see light at the end of the tunnel.
                600W, 40A MPPT, 230AH FLA,24V Samlex 1500W

                Comment


                • #9
                  Thanks all. I now have a grounding rod driven 5 feet into the ground. The inverter ground lug and neg battery terminal are now attached with some wimpy wire. Will order some bare copper ground leads?
                  600W, 40A MPPT, 230AH FLA,24V Samlex 1500W

                  Comment


                  • #10
                    Is the 5 feet a typo. Just to be clear to be code compliant you need (for rods).
                    • 5/8" 8' diameter rod style ground rod (like the one you linked). It is in the ground the full 8' (can be in at up to a 45 degree angle) 250.52(A)(5)(b)
                    • A second rod (same that you used for first) at least 6' away (unless you go through all the stupid ground resistance measurement stuff, easier to just drive in a 2nd rod). 250.53(A)(2) and (3)
                    • Continuous wire (this is your GEC) bonding the array and the first rod. 250.64(C) If you do splicing it must meet subsections of (C)
                    • There are protection requirements for the GEC to protect it from physical damage and using #6 wire makes those easier. 250.62(B)
                    • The 2nd rod can be bonded to the first rod by a clamp / wire / clamp. It does not have to be the same continuous wire that bonded the first one. 250.53(C) So if you forgot the 2nd rod, just buy another with two clamps, pound it in at least 6' away and run a #6 between the two rods using the two clamps. Makes this part super easy - make sure the entire #6 wire bond is underground and (I was told this by my AHJ but can't find it directly in the code) 18" deep so that is what I did - 18" deep.

                    Comment


                    • #11
                      First rod now submerged full 8 feet with clamp at top, 2nd rod on the way, which I will drive in 6 feet away, and attach clamp 18" from top. The 18" deep trench digging starting at rod 1 at ~1" terminating at rod 2 at 18" is now being dug. Will join the 2 rods with 4AWG (and clamps), which is same wire as the inverter to rod 2, which will also have the batteries grounded to. Does that sound right? Thanks.
                      600W, 40A MPPT, 230AH FLA,24V Samlex 1500W

                      Comment


                      • #12
                        Originally posted by Gdwats View Post
                        First rod now submerged full 8 feet with clamp at top, 2nd rod on the way, which I will drive in 6 feet away, and attach clamp 18" from top. The 18" deep trench digging starting at rod 1 at ~1" terminating at rod 2 at 18" is now being dug. Will join the 2 rods with 4AWG (and clamps), which is same wire as the inverter to rod 2, which will also have the batteries grounded to. Does that sound right? Thanks.
                        If it's worth doing, it's worth over doing !
                        Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
                        || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
                        || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

                        solar: http://tinyurl.com/LMR-Solar
                        gen: http://tinyurl.com/LMR-Lister

                        Comment


                        • #13
                          Better to over do, than to do over(I learn the hard way).
                          More than anything, this has been a learning experience. I've wasted more money than I should have, but it was cheaper than an electrical course! Much of the leftovers can be sold off to cop back some cash : 20A MPPT, 300W 24V pure sine inverter, 500W 12V modified inv, 2x55AH 12V drop cycle sla...), all with low milage.
                          At any rate, I'm set up to go just a bit bigger yet. Thinking 2 more panels to max out the 40A, 100V controller, or one 200W if i can find one available at 24V, to make 2x400W PV Series arrays.
                          600W, 40A MPPT, 230AH FLA,24V Samlex 1500W

                          Comment


                          • #14
                            Originally posted by Mike90250 View Post

                            If it's worth doing, it's worth over doing !
                            As a Mechanical Engineer once told me, "if you are unsure of exactly how big a foundation you will need, just put more concrete in the hole"

                            Comment


                            • #15
                              Originally posted by SunEagle View Post

                              As a Mechanical Engineer once told me, "if you are unsure of exactly how big a foundation you will need, just put more concrete in the hole"
                              Insider's ME secret: You EE's think you're so slick w/ Power Factors. HA !! ME's can make things disappear into imaginary plane besides Power Factors. That's where high density concrete comes from (or goes to). Same mass, less volume.

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