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junction between PV cables and THWN in conduit

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  • foo1bar
    replied
    Originally posted by RShackleford View Post
    I'm not sure NEC allows "modifying" a part by drilling holes; duh, I guess you have to though, because most of the boxes I've found have no holes or knockouts at all.
    Definitely is allowed.
    Holes should neat and tidy of course - the whole "neat and workmanlike manner" rule.

    If you're doing PVC conduit (which it sounds like you are) I would make sure to put the hole far enough from the walls of the box. You want to be able to insert the "box adapter" through the hole to connect into the female PVC conduit opening that you're connecting to. If It works out nicely I have the bell-end of the conduit against the box, I think it looks nicer than a coupler - but sometimes you need to go into an LB or use a conduit coupling. BTW, I've been able to make some nice bends with a big pot of boiling water to heat the conduit - it's barely hot enough, but better that than winding up with a scorch mark.

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  • RShackleford
    replied
    The kinginnovations website doesn't show any such animal as a 600v-rated Alumiconn; I guess people are talking about the similar (but more expensive) NSI Polaris ?

    Thanks for the wire-nut wisdom @Mike90250.

    Thinking that 4-port 985-GP-04 is the way to go.

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  • Mike90250
    replied
    I've seen too many scorched twist on wire nuts to be able to endorse them. Terminal blocks, polaris or split bolts are much more secure and less prone to invisible errors inside the spring cap.


    > Almost seems like you could just use a regular wirenut and squirt some silicon caulk in there.


    NOOOO !!!! Silicone caulk is corrosive to copper, it has a vinegar component to the cure cycle (smell it sometime) The expensive electrical cable rated caulk uses a neutral cure.

    The weatherproof wire nuts use silicone GREASE in them.

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  • RShackleford
    replied
    Originally posted by bob-n View Post
    One ground wire from load center to ground rod. This is already in place before installing solar.
    One 6-AWG ground wire from rails to ground rod.
    One ground wire from load center to inverter. There will be a large screw-strip in the load center for grounds. You can simply run red/black/green THWN from inverter to load center. Red & black go to the breaker and green goes to the ground screw-strip.
    I'll actually put a new ground-rod in at the array.
    The SunnyBoy wants a neutral connection too; I might run Romex, because the inverter is probably gonna be on the outside wall of the house, and the wires come out the bottom of the inverter, so it may easiest to go down into the crawlspace (using conduit) through the band joist, and then over and up into the load center - so pulling Romex through conduit that short distance may be easier than adding a box inside the band joist to transition from THWN to Romex (or running conduit all the way to the load center.


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  • bob-n
    replied
    One ground wire from load center to ground rod. This is already in place before installing solar.
    One 6-AWG ground wire from rails to ground rod.
    One ground wire from load center to inverter. There will be a large screw-strip in the load center for grounds. You can simply run red/black/green THWN from inverter to load center. Red & black go to the breaker and green goes to the ground screw-strip.

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  • RShackleford
    replied
    Originally posted by bob-n View Post
    I was thinking of the ground connected to the rails and panel frames. That wire goes directly to the ground rod(s). The house has another wire from ground rod to panel. In the event of a nearby lightning strike, we want the high-current pulse collected by the panel frame going right to earth, not going through other cables or the house wiring.
    Oh yeah, I'm doing that too - 6awg/bare/solid connecting the rails directly to a ground rod. Only question is best way to get wire coming from inverter (or main load center) to PV array connected to the 6awg.


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  • bob-n
    replied
    For ground, inside is fine and outside is fine. Whatever works in your system is fine.

    I was thinking of the ground connected to the rails and panel frames. That wire goes directly to the ground rod(s). The house has another wire from ground rod to panel. In the event of a nearby lightning strike, we want the high-current pulse collected by the panel frame going right to earth, not going through other cables or the house wiring.

    Leave a comment:


  • RShackleford
    replied
    Originally posted by bob-n View Post
    Here's a photo of a 985-GP-04, which is like four 600V 2-wire Alumiconns in one plastic block:
    9152946962462.jpg
    That looks perfect for my two strings, but about $20 to get one to my doorstep. The NSI Polaris are crazy expensive.

    I think I'll try those DryConn wirenuts first. Don't understand mistrust of wirenuts. Yes, it's a potentially damp location, but the silicon seal seems to address that; a little confused how that works (in the DryConn) though. Almost seems like you could just use a regular wirenut and squirt some silicon caulk in there.
    When I had a similar wiring problem, I elected not to run the big ground into my sealed junction box. My ground wire was AWG 6 stranded, and there was no feasible gland for stranded bare wire. I just ran the ground along the conduit with cable ties and to the ground rod. In retrospect, it would have been smarter to get insulated ground wire, but I would have still run it outside of the conduit.
    How come outside the conduit ? I'm thinking I'll make my ground be 10awg/insulated/stranded, run it inside the conduit. Then just bring it outside the j-box through an appropriate gland, and tie it to the 6awg solid wire with a clamp-style connector.



    Last edited by RShackleford; 05-12-2020, 08:23 PM.

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  • bob-n
    replied
    Last time I looked, NSI Polaris connectors were quite expensive, but good.

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  • Ampster
    replied
    The more expensive NSI brand ones are rated for 600 volts. I did not realize the Dri Conns were good for 600 volts since I use them regularly for sprinkler wires. I am still not a fan of wire nuts and may swap out for the NSIs. I know @Mike90250 has an opinion on wire nuts.

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  • bob-n
    replied
    When I had a similar wiring problem, I elected not to run the big ground into my sealed junction box. My ground wire was AWG 6 stranded, and there was no feasible gland for stranded bare wire. I just ran the ground along the conduit with cable ties and to the ground rod. In retrospect, it would have been smarter to get insulated ground wire, but I would have still run it outside of the conduit.

    Yes, Alumiconns and DryConns are both very good. You could also check out Marathon 985-GP-xx connectors, where xx is the number of isolated circuits. These are rated 85A, 600VAC/DC. For example, a 985-GP-04 has four separate circuits, and each circuit accepts two large wires up to AWG 4 or multiple smaller wires. These are available from electronic distributors and also some dealers on Amazon, but not big box stores. Google the part number for specs and dealers. Here's a photo of a 985-GP-04, which is like four 600V 2-wire Alumiconns in one plastic block:
    9152946962462.jpg

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  • RShackleford
    replied
    Originally posted by Ampster View Post
    I tried to post a link and details but it delayed in moderation.
    Yeah, this site does some annoying stuff. The latest thing is it seems to want me to log back in almost every time I come back to the site, multiple times per day when I'm this active in a thread.
    In the meantime here is a photo and the name is Alumiconn alumiconn-wire-connectors-wire-terminals-95125-0-64_1000 (1).jpg
    Looks nice, but it's only rated to 300v - not high enough for most string-based systems. Those DryConn's are 600v, cheaper, and seem like they'd work well.


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  • Ampster
    replied
    I tried to post a link and details but it delayed in moderation. In the meantime here is a photo and the name is Alumiconn alumiconn-wire-connectors-wire-terminals-95125-0-64_1000 (1).jpg

    Leave a comment:


  • bob-n
    replied
    Like you, I was taught to never modify electrical components, as that violates the listing. But I'm not certain the exact wording on modification in the code.

    One of the vendors of these sealed boxes is Cantex. That's the brand carried by many big box stores. This video from the Cantex website is instructions for installation these boxes and specifically directs you to cut holes in the sides of the box. I guess that means that the box will not be modified by cutting holes, because that is the intended use method, just like knocking out metal coins.
    https://youtu.be/we5Y--w6fcw
    Cantex sells the same basic box in sizes from 4x4x2 to 12x12x6, and all carry UL listing and NEMA ratings for types 1, 3, 3S, 4, 4X, 5, 6, and 6P. NEMA 6P is pretty darn good, allowing "prolonged submersion at a limited depth". Cantex part numbers are 51337xx, where xx is two digits to specify the specific size box. Their catalog says:
    UL Category QCUP
    UL File #E205935
    Control #92CM
    I have no clue what all of that means.

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  • RShackleford
    replied
    For the connectors, maybe you mean DryConn: https://www.lowes.com/pd/DryConn-Aqu...ectors/3377352

    Drip loop is a great idea. Do you have a link for that (or similar boxes) ? I need more openings for my two strings. I'm not sure NEC allows "modifying" a part by drilling holes; duh, I guess you have to though, because most of the boxes I've found have no holes or knockouts at all.

    I don't see the copper ground at all; you ran the copper inside the conduit ? But if the hole at bottom allows moisture to escape and that's good enough for the ground, which opens into the same box, seems kinda like you don't really need gland for PV wires either.
    Last edited by RShackleford; 05-12-2020, 03:53 PM.

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