Wiring for Conext MPPT80A/600V - does this sound ok / is this to code?

Hi all,

I have my MPPT80 mounted to the left of my XW+PDP on the wall just due to how space worked out. To wire it, I was going to run 1" PVC conduit from a knockout on the Left side of the unit, over to the bottom of the PDP - in that conduit I was planning to run the two #2 battery +/- conductors, and the #6 ground conductor from the ground rail in the MPPT80. On the Right side of the unit I was going to run 1" PVC conduit to the great outdoors, with #8 wiring in it off to the solar array. Wire gauges and conduit fills all seem ok according to various calculators.

My main concern with this approach is the #6 in with the battery conductors - is this ok, or should I route the #6 ground cable out the right side of the MPPT (thinking of the Lexan barrier inside the wiring compartment here).

Any advice would be appreciated. This is going to be inspected, so I want to get it right (and not burn my house down)!

Thanks!

Comments

  • VicVic Solar Expert Posts: 2,998 ✭✭✭✭
    Hi Rossman,

    Am not a Code expert, and there are many variables in Codes, local practice, and just what a particular Inspector wants to see, as well as what the AHJ has to say.
    In addition, the Code for grounding in Ontario is probably a bit different than in the US, and so on.

    However, believe that you would be well served by looking at grounding from a System perspective, and perhaps not by sub-systems.

    Would think that Schneider would have System wiring diagrams in the Manual for the XW inverter, or perhaps in the manual for the PDP, or whatever they call their conduit box/es.

    Depending upon what is considered to be the rating of the largest circuit breaker, it is possible that #6 AWG might not quite be large enough -- there is probably a 250 A DC breaker for the inverter, and so on.

    On the DC side of the systems here, we use #4 AWG cable to bond the inverters to the ground buss on the DC side, and a #4 AWG to the grounding electrode.

    There are details about how to handle the Equipment Grounding Conductor from the PVs to the rest of the system, and some AHJs have a particular method required, that may not be the best for near-by lightning strikes.

    It is often best to ask the AHJ/Inspecting authority just how they expect system/subsystem grounding and bonding to be handled.

    I have my own way of handling this, for the requirements here, but that is not necessarily the way that it needs to be done for your Inspectors. 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.
  • RossmanRossman Solar Expert Posts: 178 ✭✭
    Vic,

    Thanks for your comment. Appreciate the various regional and code differences.
    Vic wrote: »
    Would think that Schneider would have System wiring diagrams in the Manual for the XW inverter, or perhaps in the manual for the PDC, or whatever they call their conduit box/es.

    Oh, they have a diagram, but it is not really clear which conductors could run in a conduit with which other conductors in this case. Most of the time it is reasonably obvious. I, prehaps mistakenly, assumed that because the XW is connected to our house AC wiring, that it would share the ground with that. Are you generally supposed to have a different ground wire and electrode for the DC side as well? There is nothing like that pictured in the XW documentation, just a single AC house ground that connects to the XW.

    So much to learn, unfortunately there don't seem to be many DIYer references out there :( I will talk to my local inspector when he comes back to inspect our house AC wiring.

    Cheers!
  • VicVic Solar Expert Posts: 2,998 ✭✭✭✭
    Hi Rossman,

    I have assumed that you are off-grid, but this might not be correct. Your system is fairly large, so it might be Grid-connected.

    You can run equipment grounding conductors in the same conduit as the AC power, just needs to be the same insulation rating as required for the AC conductors ...

    All of this has so many variables, including the distance between what you call the Main Panel in the system, weather you sill need a grounding electrode at the power room for the XW stuff, batteries etc, and how you should connect these two (or perhaps more) grounding electrodes, and so on.

    We are off-grid, make the AC Neutral to Ground connection at the inverter's AC Conduit box, and not at the residence (or shop) panels. We have multiple ground electrodes, and UFERs, which are all connected together with a bare trench ground wire, and a grounding cable in the conduit with the AC conductors to each building.

    Another variable is your Code, and the code changes every three years in the US, so just which code that the entity that does the inspection has Adopted, also matters.

    Since you will need an Inspection, perhaps you are Grid Interactive, so this could change a few things ...

    Your post was just sitting here, and thought I'd try to get the ball rolling. There are a few folks here, willing to speak to the grounding/earthing dynamics, since I hate to argue, I am not one of them.

    Think that it is Vacation season, around here. FWIW 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.
  • RossmanRossman Solar Expert Posts: 178 ✭✭
    Thanks again Vic!

    We am in Ontario, Canada, so not quite the same rules as the US unfortunately. I have been using an Ontario Electrical Safety Code "cheat book" as my guide for house wiring - unfortunately does not cover anything about DC or off-grid type stuff. But it has served us well on the AC side of things!

    We are indeed off-grid. I am not actually 100% sure, if our solar stuff has to be inspected. When I spoke with the ESA to get my regular AC house wiring permit, I did mention that we would be off-grid with solar and they said something about their being a separate solar permit that I would need to get. I am not sure if they misheard and thought I may connect my solar to the grid, who knows (lots of people around here doing that) In any case - passed our rough-in inspection no problem just trying to get the last odds and ends squared away for our final on that front. In the meantime trying to get the solar array connected, right now charging batteries solely from the generator which is a little annoying to stay on top of.

    Discovered today that, running two #2 and a #6 through a 1" conduit is tough going! Am not sure how Schneider expected this to be wired, the cabinet knockouts seem well suited to 1" conduit. Certainly, can not get two #2's through a 1" LB fitting :-/ Back to the drawing board.

    Cheers!
  • VicVic Solar Expert Posts: 2,998 ✭✭✭✭
    Rossman,

    Well per NEC, the maximum Sch 40 PVC Conduit (assuming) Fill from a table is 3ea #2 AWG THHN//THWN conductors. Your standard building wire may be a bit different than ours. THHN is a Compact cable, with relatively thin insulation, and also has a Polyester coating (slippery) that makes this cable easier to pull in conduit. Your standards may dictate a different type cable, with different specs for conduit fill. Our #2 Copper THHN uses 19 strands of wire.

    You can holesaw or punch the knockout hole in the conduit box to a larger size 1 1/4" or even larger if needed. There are pulling lubricants available if friction is the issue. If holesawing the knocked out knockout, you can clamp a piece of wood or plywood over the 1" hole, to act as a center for the holesaw's pilot bit, as you probably know.

    Wish I could be of some help. Looks to be a very capable system. Have fun with it. 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.
  • RossmanRossman Solar Expert Posts: 178 ✭✭
    Vic, thanks again for your comments! Am sure I will figure something out!
  • SkiDoo55SkiDoo55 Solar Expert Posts: 414 ✭✭✭
    Looked up the knock-out sizes on XW mppt 80 and the smaller ones are 1.250"/1.375" ( 1" & 1.25" conduit) and the larger one for battery cable is 1.7" should take a 1.5" fitting. Hopefully you are using either EMT or Non-metallic electrical conduit.
    Concur that per the tables 2-3 of #2 should fit in a 1" conduit, and bend through an standard LB probably tough if using a short LB. if using some form of different cable to battery with heavier coating ie: battery cable will need to use the larger conduit knock-outs.
    GT3.8 w/4600W Trina 230W, TX5000 w/5000W ET-250W, XW4024 w/1500W ET-250W, 4 L16, 5500W Gen. (never had to use) Yet!!
  • RossmanRossman Solar Expert Posts: 178 ✭✭
    Thanks SkiDoo, I guess I could switch and use the larger knockout and use 1 1/2" conduit. But at the PDP there are only 1" knockouts for me to use on the bottom (or a larger 3"), so that would mean some kind of transition I suppose. I was using sch40 PVC rigid conduit for this installation. It is a shame Schneider does not provide more guidance in this area (recommended conduit/knockout sizes to use for which conductors).

    Appreciate your comments. The #2's, there is no way they would loop and fold properly in the 1" LB fitting I got. I guess I can use a 90 instead of the LB, then the turn is not so tight. Who knew working with #2 was so difficult! On a semi-related note, I don't understand why the Schneider MPPT sizing tool recommends "#6 - #14" wire for the cc->battery run, there is no way it can carry an 80A load.
  • SkiDoo55SkiDoo55 Solar Expert Posts: 414 ✭✭✭
    In the install manual #6-14 is for the PV input to the MPPT, #2-14 is for the battery. The sizing tool will give you recommended based on your solar input that you manually entered. Yes #6 won't handle 100 amp for very long. The calculator I use shows #3 as smallest for 80 amp cont load, 100 amp breaker. That is what would be required for a code compliant system where wire size is based on rated max output of the controller.
    Opened designer they have an error in the recommended copper cable size for charger to battery, don't know what tables they are using?
    GT3.8 w/4600W Trina 230W, TX5000 w/5000W ET-250W, XW4024 w/1500W ET-250W, 4 L16, 5500W Gen. (never had to use) Yet!!
  • SkiDoo55SkiDoo55 Solar Expert Posts: 414 ✭✭✭
    What are your panel/array sizes. Panel wattage, number per string and number of strings, panel mfg p/n etc. min max temps wire runs, panel to cc, cc to batt. If you walked thru the Conext Designer and input the numbers then disregard.
    GT3.8 w/4600W Trina 230W, TX5000 w/5000W ET-250W, XW4024 w/1500W ET-250W, 4 L16, 5500W Gen. (never had to use) Yet!!
  • RossmanRossman Solar Expert Posts: 178 ✭✭
    Thanks again for the comment Skidoo!
    SkiDoo55 wrote: »
    The sizing tool will give you recommended based on your solar input that you manually entered.

    Well, it should, but it doesn't seem to. It has three panels on the "Cables" screen, Panels to Array Combiner box, Array Combiner box to Charge Controller, and MPPT Charger to Battery. Under MPPT Charger to battery it says, "Recommended Copper Cable: 6 - 14AWG". *shrugs*
  • RossmanRossman Solar Expert Posts: 178 ✭✭
    SkiDoo55 wrote: »
    What are your panel/array sizes. Panel wattage, number per string and number of strings, panel mfg p/n etc. min max temps wire runs, panel to cc, cc to batt. If you walked thru the Conext Designer and input the numbers then disregard.

    I did use their designer tool but it is not the greatest, it seems not to understand what value you enter for cable lengths :(

    Here's part of the report:
    http://i.imgur.com/EFPvR39.png

    See how for the Charger to Battery cable length is set to 22m?? I entered 2 metres. *sigh*
  • RossmanRossman Solar Expert Posts: 178 ✭✭
    SkiDoo55 wrote: »
    The calculator I use shows #3 as smallest for 80 amp cont load, 100 amp breaker.

    Also thanks for saying this part specifically, as I got two 80A breakers and I guess that clearly is not enough. For some reason I thought, "It's an 80A charge controller, guess I'll need 80A breakers!"

    I will order in some proper 100A breakers, thanks!
  • VicVic Solar Expert Posts: 2,998 ✭✭✭✭
    Rossman,

    Know that it can be a pain, and expensive to import items into Canada, even from the USA, but, FWIW:

    http://www.solar-electric.com/instal...t-breaker.html

    Know that you had some difficulty if getting appropriate breakers for the Schneider conduit boxes In the past. These breakers, to me, seem like a deal.

    And, you might be trying to make a Service Loop inside the 1" LB (assume that you are NOT using an SLB). There is simply no room for this. You can make a neat service loop inside the CC wiring compartment, if there is enough room, or perhaps inside the other end of the cable run. Do not know the spec on the cables that you are using for this run, and, what you must use in Canada might be different than our standard Building Wire -- THHN/../../.. compact conductors, and therefore might be larger ... You should be able to pull the cable out of the LB (with its cover removed), and, then push that hank back into the LB, and up into CC (of course depends upon which direction you are pulling the cable), if the cable that you are using is something like our THHN 19-strand Copper cable.

    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.
  • RossmanRossman Solar Expert Posts: 178 ✭✭
    Hey Vic,

    I already have those breakers in my shopping cart! Shipping is a bit steep, but, what can you do, I think they are the best (and easiest) source for them for me.

    For my ground cable I bought #6 like this:
    http://www.homedepot.ca/product/electrical-cable-copper-electrical-wire-gauge-6-19-t90-6-19-green-300m/966030

    and for the #2 it was like:
    http://www.homedepot.ca/product/electrical-cable-150-copper-electrical-wire-gauge-2-7-rw90-2-7-black-300m/867835

    I don't know how that compares to what you guys source in the US, or whether those were particularly good choices, but it's what was available. I only bought a little just to test out my ideas with so will need to purchase more to finish this off properly. Maybe I should get #3 which would make things a wee bit easier.

    As for the LB fitting, I tried to do the wiring as you suggest, and with a service loop but i was unable to feed the #2 around the tight bend out of the LB either way :( Ended up tearing up a bit of the wire insulation trying to manhandle it through, annoying. Sure is tough stuff to work with.

    Any further advice or thoughts are, of course, very welcome!

    Thanks,
    mark
  • VicVic Solar Expert Posts: 2,998 ✭✭✭✭
    Hi Mark,

    OH !! That #2 gauge cable is only 7-strand, and XLPE jacket Service Entrance cable. It IS probably rated for direct exposure to the elements outdoor. It probably can be pulled through conduit ... it says that it can, but most SE cable has thick insulation, and some like our RHH is double-jacketed, IIRC.

    Believe that you folks cannot use our THHN cable, which IS 600 V insulated, but it has a relatively thin jacket.

    The #6 cable that you Linked, IS 19-strand, which is much more flexible than 7-strand. Your 19-strand Building Wire may still have a fairly thick jacket. This might reduce the Max conduit fill number. There are probably different Fill Tables for Canada, if your standard 19-strand Building wire has a thicker jacket than our THHN.

    Need to visit another site, now. Did not quickly find a spec on that #6 wire to see how the jacket thickness compares to our THHN ... will look later. Thanks for the added info.
    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.
  • VicVic Solar Expert Posts: 2,998 ✭✭✭✭
    Hi Mark,

    OK the Southwire cable that you bought for the Ground cable -- T90 #6 Ga appears to have the same stranding, insulation thickness, and overall cable diameter as our THHN: It also has the same Polyester (Nylon) easy-pull coating.

    http://www.southwire.com/ProductCata...rodcatsheet195

    So, it will be considerably easier for you to pull and route #2 T90, than that XLPE 7-strand cable that you have. For exposure to elements, the RW cable would be better, but probably would be better to run this in conduit ... depending.

    Just pulled four #2 Ga plus six #6 Ga cables here, but that was through 2" rigid metal conduit ... 'twas a dream, but that is considerably smaller fill that what you are doing.

    The T90 has; a thinner, more flexible jacket, and finer stranding than the RW90, all of which should make pulling and routing two #2 Ga and one 6 Ga cables much easier. In the interim, you may have chosen a different path.

    FWIW. 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.
  • RossmanRossman Solar Expert Posts: 178 ✭✭
    Vic - I will see if I can find this T90 cable in #2 around here, thank you so much for looking into it for me! I am going out tomorrow to try and hunt down the right stuff as well as some other misc electrical parts, will report back!

    Edit: Seems I *should* be able to buy some of this, it seems to be the right kind per your comment: https://ontario.westburne.ca/t90-twn-thhn/westburne-wire-cable/twn-2-19-black-cu-wire-cut/product/TWN2%252F19B
  • VicVic Solar Expert Posts: 2,998 ✭✭✭✭
    Hi Mark,

    Yes, based on what is listed on the Westburne site, it APPEARS that that cable should be OK. Just to be clear, I know nothing from direct experience of the Codes in Canada, and have read that there are some differences in the specs for wire/cables used in wiring systems there.

    I have never pulled any of our THHN #2 AWG cable into 1" conduit, or through any 1" conduit body. It might take a bit of shoving, pushing, and in my case, a bit of swearing. But, the Conduit Fill Tables are fairly conservative, so if the Table says 3 ea # 2 AWG THW/ T90/ THHN cables WILL fit into 1" Conduit, I take that to mean that it will fit, without too much pain or blood loss.

    Did look on the HD site you linked to for the #6 T90, but found no #2 AWG T90. So the Wesburne suppliers may be able to tell you how appropriate that cable is for your use in this application.

    Do not know how far you need to travel to buy electrical items, but you could consider enlarging the existing hole in the CC & PDP, and using 11/4 or 1 1/2" conduit and fittings to make things easier ... often unused items are returnable for full credit, at least around here.

    Sorry to be so cautions, but hate to tell someone weather something is OK or not, especially when the applicable codes are completely unknown to me.

    So good luck. These installations are FUN, so enjoy. 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.
  • Ethan BrushEthan Brush Solar Expert Posts: 231 ✭✭
    Rossman,

    One suggestion i would have - assuming the layout and equipment is compatible - is to mount a 4x4 wireway under the three pieces of equipment and come out of the top of that straight up into the bottom of each piece if equipment. Makes for a clean install and easy wire pulling/management. Im an electrician so I'm done with hard wire pulls, undersized lb's, scraped knuckles, etc :)
  • RossmanRossman Solar Expert Posts: 178 ✭✭
    One suggestion i would have - assuming the layout and equipment is compatible - is to mount a 4x4 wireway under the three pieces of equipment and come out of the top of that straight up into the bottom of each piece if equipment. Makes for a clean install and easy wire pulling/management. Im an electrician so I'm done with hard wire pulls, undersized lb's, scraped knuckles, etc :)
    Thanks Ethan,

    Unfortunately there is no knockout on the bottom of the charge controllers, so I have to come out the side :( The bottom is all a ventilation type metal mesh. Appreciate the comment regardless!
  • RossmanRossman Solar Expert Posts: 178 ✭✭
    Vic wrote: »
    Hi Mark,

    Yes, based on what is listed on the Westburne site, it APPEARS that that cable should be OK. Just to be clear, I know nothing from direct experience of the Codes in Canada, and have read that there are some differences in the specs for wire/cables used in wiring systems there.

    I have never pulled any of our THHN #2 AWG cable into 1" conduit, or through any 1" conduit body. It might take a bit of shoving, pushing, and in my case, a bit of swearing. But, the Conduit Fill Tables are fairly conservative, so if the Table says 3 ea # 2 AWG THW/ T90/ THHN cables WILL fit into 1" Conduit, I take that to mean that it will fit, without too much pain or blood loss.

    Did look on the HD site you linked to for the #6 T90, but found no #2 AWG T90. So the Wesburne suppliers may be able to tell you how appropriate that cable is for your use in this application.

    Do not know how far you need to travel to buy electrical items, but you could consider enlarging the existing hole in the CC & PDP, and using 11/4 or 1 1/2" conduit and fittings to make things easier ... often unused items are returnable for full credit, at least around here.

    Sorry to be so cautions, but hate to tell someone weather something is OK or not, especially when the applicable codes are completely unknown to me.

    So good luck. These installations are FUN, so enjoy. Vic

    Vic, thanks very much! Do realize your advice is not "legal" advice but it is a start - feel I am closer to a solution than I was a couple days ago ;) If I get it all wrong the inspector will tell me I screwed up so I am not overly worried... I will be going out today to try and get some T90 #2 and some other misc stuff, will report back how I get on, hopefully Westburne sells that cable by the metre!
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,221 ✭✭✭✭✭
    Rossman,

    One suggestion i would have - assuming the layout and equipment is compatible - is to mount a 4x4 wireway under the three pieces of equipment and come out of the top of that straight up into the bottom of each piece if equipment. Makes for a clean install and easy wire pulling/management. Im an electrician so I'm done with hard wire pulls, undersized lb's, scraped knuckles, etc :)


    The XW system has convection cooling input at both the top and bottom of the equipment and so this can't be done. I agree with "done" with hard wire pulls.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • Ethan BrushEthan Brush Solar Expert Posts: 231 ✭✭
    Rossman wrote: »
    Thanks Ethan,

    Unfortunately there is no knockout on the bottom of the charge controllers, so I have to come out the side :( The bottom is all a ventilation type metal mesh. Appreciate the comment regardless!

    Bummer!

    Well I'll try again.....another trick is to use a larger size LB/LL/LR with reducers. A little known fact, but if you look at the max allowable size/quantity of conductors stamped on the LB/LL/LR fitting (314.28(A)(3) says you can use those figures rather than the standard NEC sizing method), it ends up being quite a bit less than the max allowable fill for the same trade size conduit. Many Many LB's are actually too small for what is put in them even if the raceway fill is compliant.
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