Din Rail breaker wiring and spacing questions...

PhotowhitPhotowhit Solar Expert Posts: 5,222 ✭✭✭✭
We'll I'm un-'jerry rigging' my E-panel and installing Din rail breakers, and had a couple questions.

I'm bringing in 4 gauge wire but the connections are rated at 6 gauge, They appear to fit in the connectors, is it ok to go ahead and use the 4 into the connectors?

Since I'm bringing in #4 I'd like to space the breakers and use every other space, or leave room for a breaker between the ones I'm installing, I'm worried that they will be a little wobbly if I do this, any problem with that?

Also I think I will move the AC Din rail below the DC din rail in the E panel, this is a seperate plate that I will flip around, so are the breakers centered over the rail? So I'll just need to flip the breakers around so that off is down.

I won't have a genny or outside AC source, I'll leave the genny switched breakers(can't think what you call this setup right now, by pass switch?) and run only the out put AC through the single AC breaker. I mention this since I also intend to relabel and repurpose a couple of the AC bus bars for DC use, with 3 charge controllers there isn't a lot of room on the DC hot for larger cables 4-4 gauge or better with 80-90 amp potential comming off the charge controllers.

To make things interesting I had also wanted to put in lightning protection on the AC side, so I guess combining wires at the breaker is not to code? I could repurpose/relabel the short DC bars...
Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol

Comments

  • VicVic Solar Expert Posts: 3,003 ✭✭✭✭
    Re: Din Rail breaker wiring and spacing questions...

    Hi .. whit,

    Looks like you are progressing.

    Personally, would not run #4 AWG into the DIN breakers, and would NOT leave a breaker space twix them, both for reasons of mechanical rigidity. If you had a fairly long service loop for the #4 going to the DIN bkrs, might be OK, but the #4 will place some side load on breakers, especially without a neighboring breaker to transfer the side load among neighbors. IMHO, these breakers need to be a block, each assisting its neighbor to attain an acceptable level of rigidity.

    Yes two wires per breaker output terminal is not a great idea, and not code. You know the recommended technique of having a dedicated breaker for each leg of the AC SPD, such that the only purpose of this breaker is to allow the SPD connection. Guess that you do not have the space for this added breaker.

    Xantrex used a trick siameesed two-headed lug on its AC Bypass breakers that allowed two wires to be connected to a single breaker terminal, but this would not be Code unelss it was submitted for approval as a part of an assembly ... know that Inspection is not a problem for this install.

    Of course, as you know, you could put the SPD(s) in a separate box which has a mini-busbar for wiring to the SPD.

    This is the fun part, but for me, being in the Center Of Nowhere, there is always something that comes up where just one or two additional parts would be the thing to make the installation work out well, and the round-trip to town is about four or more hours.
    Above just my opinions, Good Luck, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • PhotowhitPhotowhit Solar Expert Posts: 5,222 ✭✭✭✭
    Re: Din Rail breaker wiring and spacing questions...

    I didn't think about the 'mechanical rigidity'. The bypass breaker seems pretty firm, I even think there is a space between it and the other AC breaker, I'm just not familiar with Din rail breakers.

    I'm bringing #4 in from the combiner box, I have it on hand it's only an hour to the 'big city' for me, but the price of copper is nuts and a cut piece is 2x the price of roll per foot ($1.25 per for the 60 feet I need, I think it's $120 for a 250' roll) I could use #8 but if I fill out the array I'll need to go to #6.

    I had intended to take out a few strands and shrink wrap it, don't think that would help much on the rigidity angle. I'll either be real sure it's bent in well maybe bend it in and let it sit before I tighten it down? or just call Midnite and see if they have a panel mount plate with a breaker bar on the other side for one of their lite E panels. I'm getting some replacement lite displays from them, maybe if I call... I've waited this long, means ordering panel mount breakers too, heck the wire might be cheaper...

    I thought about putting a mini box for the AC outside, but I'd still need bus bars of some type so it couldn't be too mini. Since I don't have outside AC coming in, I could steal the neutral bus bar for DC hot to battery I may have enough on the Negative bar.

    Have you delt much with DC potential? wondering about the DC negative side, since the rated input from the panels would only require #6 would that be all I need to the charge controllers, but with 90Amp potential coming out + side I'll need #4. Does that sound right? I always think of DC as a curcuit requiring the same on either side? Likely a question for the Midnite people.

    Just realized you have to wire them then slide them on the rails, well heck...
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • VicVic Solar Expert Posts: 3,003 ✭✭✭✭
    Re: Din Rail breaker wiring and spacing questions...

    Hi Whit..,

    I have NO experience with MN AC Bypass Breakers, but have used some MN AC DIN-Rail breakers, and they are similar to the DC DINs in the way that they mount.

    You should be able to pull up on the Yellow plastic latch on the breaker (at least it has been yellow on DC bkrs), and put the top slot of the Din breaker on the top rail , and guide the bottom slot onto the rail and then push the yellow latch back into the latched position. Should not require sliding these Din breakers onto the rail/s.

    As you know, breakers/fuses protect wiring. So if after all of the corrections to the input current have been applied and a 60 Amp or smaller breaker on the input side will work, #6 THHN building wire should be fine. Although there is the temp rating consideration of the lugs, IIRC. But, here have used #6 THHN on the input side of Classics, protected with 60A Panel Mount (1" size) breakers.

    Yes, I DO like the Panel Mt breakers much better. Just wish that CBI the manufacturer of the MN and OB breakers had a front-facing wiring lug on these panel mounts. This would eleiminate the need for a Lug on the wire and it could be wired after the breaker is mounted. The Airpax 1" large format panel mount CF series breakers work this way and it helps a lot, but the breaker is almost twice the size of the MN PM breakers.

    Have Fun! Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Din Rail breaker wiring and spacing questions...
    Photowhit wrote: »
    I thought about putting a mini box for the AC outside, but I'd still need bus bars of some type so it couldn't be too mini.

    What about using one of the insulated multi-screw-terminal connectors common in some EU and other countries instead of bus bars? Those would not have to be mounted to the inside of the box and could also be no longer than necessary (with a spare or two for expansion.)
    SMA SB 3000, old BP panels.
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Din Rail breaker wiring and spacing questions...

    got a pic or a link to them Inetdog?
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Din Rail breaker wiring and spacing questions...

    Do you mean like these power distribution blocks? http://www.solar-electric.com/podibl.html
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Din Rail breaker wiring and spacing questions...
    Do you mean like these power distribution blocks? http://www.solar-electric.com/podibl.html

    Not quite. Those are more compact, but till need to be mounted to keep from accidental contact between uninsulated live parts.

    What I was thinking of is used as a replacement for wire nuts in junction boxes. There are no live parts which protrude past a flat insulated surface, so not chance of accidental contact.

    Something like this for example.Attachment not found.
    SMA SB 3000, old BP panels.
  • mtdocmtdoc Solar Expert Posts: 600 ✭✭
    Re: Din Rail breaker wiring and spacing questions...

    Based on my recent experience expanding my system with midnite breakers I would concur with what Vic and others have said. I would not try to use DIN breakers with # 6 AWG or larger wirel Use the MN panel mount breakers - and unfortunately yes, that does mean lugs crimped on the ends of the wires. If your epanel is tight on space adding a MN quad box for these breakers is an option.
  • PhotowhitPhotowhit Solar Expert Posts: 5,222 ✭✭✭✭
    Re: Din Rail breaker wiring and spacing questions...

    Using all panel mount breakers is a non-starter, unless they make a panel breaker plate with a din rail breaker to replace the "AC din rail and DC din rail" plate. Unless of course I could get a Panel mount and GFCI plate like the other side. But with 3 Charge controllers I'll need 6 DC breakers. Plus of course the inverter breaker.

    I ran the 4 -#4 through 1" conduit (3-90's) and I flopped the Din Rail plate placing the DC breakers at the top, I'm still not sure if I'll just put in the #4 or if I'll strip it down and shrink wrap it, but I realized I can tighten down the lugs from the front of the breaker, by just removing the plate. I don't think wiring the din rails will be much of a problem, with them at the top and I have a nice 'J' shape path to bring the wires into the breakers.

    I did come across another issue, It appears that the battery negative bus will have 6 4 gauge wires going to it! I asked about the potential current for the negative line going to the Classic Charge controller, I'll have 6 gauge positive going into it from PV Din breaker but 4 gauge going out to the 90 Amp breaker. boB said the amperage for the negative line would be the difference between the 2 but Ryan said 4 gauge would be required to meet code. IF SOMEONE WITH A CLASSIC AND A CLAMP MEETER COULD HELP CONFIRM THIS? (I belive boB, I'm sure he's done it, but if I'm going to wire 'against code' I'd just like to confirm, I can do it my self but I've taken down my very rigged wiring, and the results might effect how I wire them.

    I might just look for a piece of bus bar with 6 - 4+ openings...

    I'll shoot a photo of the din rail breakers if I don't get completely rained out tomorrow, I did discover the bypass hardware is integrated into the plate, I left it installed when I flipped it.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • SolaRevolutionSolaRevolution Solar Expert Posts: 407 ✭✭✭✭✭✭
    Re: Din Rail breaker wiring and spacing questions...
    Photowhit wrote: »
    I'm bringing in 4 gauge wire but the connections are rated at 6 gauge, They appear to fit in the connectors, is it ok to go ahead and use the 4 into the connectors?

    Splitting hairs in regards to the NEC:
    (I understand the realities of far-from-town and what works is different from what is code compliant);)

    If you check the temp ratings of all of the terminals on your devices, breakers, terminal strips, etc, most require that you use the 75ºC ampacity ratings for your wire sizing. This means that a # 6 copper wire which is connected to a molded case circuit breaker is rated for a maximum of 65 amps and is therefore too small for a 60 amp continuous duty breaker or charge controller (60 amps x 1.25 for continuous duty = 75 amps). This same issue requires a #3 copper as the minimum size conductor for an 80 amp CC or CB.

    In some cases the NEC required conductor is too large for the Charge Controller housing. For example the XW MPPT60 states in the manual that a #6 is the largest conductor you may connect to it. To make a code compliant installation the underwriters for Xantrex described that the proper method is to connect a minimum #4 copper to the breaker, then use a high temperature rated splice to reduce to a #6 to enter the CC housing therby allowing the #6 to be used at the 90ºC ampacity rating. (75 amps) This means that you must typically use a Burndy type terminal block, a crimp connector or a split bolt to reduce the wire size.

    While the conditions in which this could be a problem are rare, they do exist. I have seen overheated #6 copper connected to the output terminals of 60 amp charge controllers in a grid tie situation. It was a worst case scenario with the wiring of 4 parallel, fully loaded CCs bundled together in a gutter. The white insulation of the neutrals was yellow and brittle and the CCs lugs were slightly discolored.

    -Alex
  • mtdocmtdoc Solar Expert Posts: 600 ✭✭
    Re: Din Rail breaker wiring and spacing questions...
    Photowhit wrote: »
    Using all panel mount breakers is a non-starter, unless they make a panel breaker plate with a din rail breaker to replace the "AC din rail and DC din rail" plate. Unless of course I could get a Panel mount and GFCI plate like the other side. But with 3 Charge controllers I'll need 6 DC breakers. Plus of course the inverter breaker.

    Which MN ePanel do you have? My prewired ePanel came with all panel mount breakers on the DC side. When I recently added my second Array and second Classic CC, I had to add a quad box to accommodate 2 more panel mount breakers.
  • PhotowhitPhotowhit Solar Expert Posts: 5,222 ✭✭✭✭
    Re: Din Rail breaker wiring and spacing questions...
    mtdoc wrote: »
    Which MN ePanel do you have? My prewired ePanel came with all panel mount breakers on the DC side. When I recently added my second Array and second Classic CC, I had to add a quad box to accommodate 2 more panel mount breakers.

    Likely you have a similar box to mine with an empty din rail on what I woul guess your calling the AC side, which in my case has a nice 175 amp DC breaker on it. The E-Panel I have is an E-Panel Lite. There really isn't an AC and DC side, you can actually put AC and DC breakers on the same Din rail(Midnite even sends the required spacer) So if you had wanted you could have added a din rail breaker and used the last panel mount slot for a 80 or 90 amp out put breaker when you added your second Charge controller. I want to plan ahead as I'll end up with 3 Charge controllers and, I hope, 1 E-Panel, with just the added box as in the photo.

    I described it as a "AC din rail and DC din rail" plate since i always through that was their intention, and had seen some E-Panels wired that way.

    I got rained out today, so I'm off to town, I'll look for a bus bar with just #12-#4 slots to replace the one with 4-#4 and multi #6 slots.

    SolaRevolution - If I understand what your saying is the the wire capacity for the series of Din rail breakers was based on the max carrying capacity of the max rated wire (#6) so I would hope/guess that my using a 50 amps breaker would be closer to allowing it to function in a higher temp enviroment? Not really sure I'm following you. The heavier wire, should have not real effect being able to handle heavier capacity than the breaker and the breaker should limit it, having #4 going into one side and #6 out the other, particularly in a polarized breaker... I didn't / don't understand the problem. Could you perhaps dumb it down...

    ...or perhaps your talking about my possibly using boB's understandiong of the negative only handling the difference between the incoming and the out going Amps at the charge controller? and understanding that where I might 'break with code' is running a #6 negative wire rather than the code required #4 to match the outgoing wire from the Charge controller?
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Din Rail breaker wiring and spacing questions...
    Photowhit wrote: »
    ...or perhaps your talking about my possibly using boB's understandiong of the negative only handling the difference between the incoming and the out going Amps at the charge controller?

    I *think* that the situation he is referring to is one where the panel negative, the CC negative and the battery negative are all connected together at a bus bar or the battery bank negative connector.
    That means that there is a return path directly from the battery bank to the panels without going through the CC. But the CC still needs its own negative connection so that it can power itself from the battery, among other things. If you have not grounded and commoned the panel negative to the battery negative, this will NOT apply and the return current from the CC will end up going back to the panels via the CC negative lead.

    For a PWM controller, there is essentially no difference between the panel output current and the battery input current, so the only current which would have to flow though the CC's - lead would be any power lost in the CC itself.

    But with an MPPT controller, the CC is supplying more current to the battery than it is getting from the panel, so the common point of the battery and the panel will NOT be able to balance out that current. Instead the "extra" current that the MPPT CC is generating must flow through the CC negative lead.

    Hope that clarifies things. It would be better with a picture, but I am graphically challenged. :-)
    SMA SB 3000, old BP panels.
  • PhotowhitPhotowhit Solar Expert Posts: 5,222 ✭✭✭✭
    Re: Din Rail breaker wiring and spacing questions...

    Thanks, that helps me visualize what boB said, heck the description is a beautiful picture! I'll still run #4 if I can, since Ryan says that's code, and I guess I might be able to get over 60 Amps difference if I do the over sized phase 2 (2.65 KW potential), so I'm topping out the Classic and I've drawn the battery down a bunch.... but I'm sure I'll run the panels in pairs and they are true 24V panels...

    Of course that CC is still a figment of my imagination and the the porch and panels above them are what's left in my 2nd bedroom and back yard...but I've left room and made plans...
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
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