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  • Quick question about junction box connections for the pros

    A quick question for the pros on this site.

    What is the consensus on using the type of connectors below in a junction box to connect the strings to the wires going to the inverter?>
    This is in Northern California, no extreme weather.

    Junction-box.jpg?psid=1.jpg

    Really bad; Not great but OK, Just fine, Great....

    Will the connection stay good for many years to come?

    Thank you
    Last edited by scrambler; 05-13-2020, 09:05 PM.

  • #2
    Not great, but OK. I'm not a fan of spring type connectors - would rather see compression type myself. We simply use wirenuts ourselves. Both are listed for this use.
    I would also put a weep hole in the low point and I don't use plastic anything on a solar array here in dry Arizona. This plastic j-box will last about 10 years on a roof here.
    BSEE, R11, NABCEP, Chevy BoltEV, >2500kW installed

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    • #3
      I'm not a pro, but I've heard a number of professional electricians (on forums) state that they don't really trust those little push-in connectors even for ordinary electrical work (i.e. indoors).

      Comment


      • #4
        I would like to see the inside of that box in a year. Looks like one of the push-in wires has come out already !

        And is the grounding clamp allowed to screw onto a stranded wire ? I don't know, but that looks iffy.
        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

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        • #5
          And have that contractor replace all the wires ! they did a ****ty job stripping the insulation off, cutting strands off the bundle, I see cut strands all over the roof. Sloppy and dangerous, as heat will build in those plastic grippers.........

          One or 2 strands per job might fly ok, but there's a bunch of copper on the roof, poor form for a power install pumping full power for hours at a time.
          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


          • #6
            I'm no pro but, the box looks too small for all that wire. Looks like the proverbial 10 pounds of s**t in a 5 pound box.
            2.2kw Suntech mono, Classic 200, NEW Trace SW4024

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            • #7
              Originally posted by Mike90250 View Post
              And is the grounding clamp allowed to screw onto a stranded wire ? I don't know, but that looks iffy

              And have that contractor replace all the wires ! they did a ****ty job stripping the insulation off, cutting strands off the bundle, I see cut strands all over the roof. Sloppy and dangerous, as heat will build in those plastic grippers..........
              Yes, lay-in ground lugs are listed for solid and stranded wire.
              I think the strands everywhere could be from them cutting the ends and restripping, or cutting off excess after stripping too much. If you look closely at the wires, I don't see any cut strands.

              And I agree with littleharbor, that box looks too small, although I don't know the volume, so I can't calculate it.

              As far as those connectors ago, I'd put them on the same level as wire nuts. Compression is ideal, mechanical screw type are great, wire nuts and Wago style spring connectors are good.

              Comment


              • #8
                Left side cable entry looks odd. Are all of those individual wires sealed? I don't know of anything code-approved that allows many loose wires entering a box through a gland. But I surely don't know everything.
                7kW Roof PV, APsystems QS1 micros, Nissan Leaf EV

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                • #9
                  Originally posted by bob-n View Post
                  Left side cable entry looks odd. Are all of those individual wires sealed? I don't know of anything code-approved that allows many loose wires entering a box through a gland. But I surely don't know everything.
                  My Solaredge inverter has a gland that will take multiple cables but it faces down. I used it for a Cat 6 cable and left the plug in the other hole. I also don't know the code with regard to high voltage cables.
                  9 kW solar. Driving EVs since 2012

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                  • #10
                    Originally posted by Mike90250 View Post
                    I would like to see the inside of that box in a year. Looks like one of the push-in wires has come out already !

                    And is the grounding clamp allowed to screw onto a stranded wire ? I don't know, but that looks iffy.
                    This is the box with only the array string wires connected to the push pin connectors, the wires from the Inverter are all out in that picture.

                    Comment


                    • #11
                      Originally posted by bob-n View Post
                      Left side cable entry looks odd. Are all of those individual wires sealed? I don't know of anything code-approved that allows many loose wires entering a box through a gland. But I surely don't know everything.
                      Probably not, although I have seen gland with a foam insert and 4 holes, if that is it it could be fine
                      The box is under a Panel so reasonably protected from rain, and we don't have a lot here in northern California, but I plan to drill a small drainage hole in that box just in case.
                      And I don't like the box is under a Panel, because that makes it impossible to easily check the status of the connection without removing one panel.
                      Last edited by scrambler; 05-14-2020, 12:30 PM.

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                      • #12
                        Originally posted by emartin00 View Post

                        Compression is ideal, mechanical screw type are great, wire nuts and Wago style spring connectors are good.
                        @emartin00
                        What do you call compression connector?

                        Comment


                        • #13
                          Thanks all, you unfortunately confirm some of my worries with that box.

                          The electrician did a great job with all the wiring in the house for the inverter and critical load panels, but someone else did the work on the roof, and that box could definitely be a lot better.
                          I will send a summary of my concerns (below) to the Installer, and probably schedule a review of the inside and connections a year from now, and at that point redo it if things are deteriorating.

                          Summary (in order of importance)
                          Push Pins Connectors are sub par, should be Compression or Screw terminals.
                          Unknown origin of cut strand, full wire shortening off (OK), or partial cut of the actual wires (bad will cause overheating and potentially lead to failure).
                          Are the Multiple wire on single Gland sealed some way?
                          Is grounding the conduit with a clamp on the Stranded wire legit?
                          Box is too small, making for cramped connections
                          Box is under a Panel, so hard to service

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