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Thread: Wiring Diagram Needed for SquareD QO Breaker Box

  1. #1

    Default Wiring Diagram Needed for SquareD QO Breaker Box

    I am in the process of wiring a square D QO breaker box to a 12VDC solar application. I am looking for diagrams and specific information on how to do this. Does anyone know where I can find pictures, diagrams, diy info online specific to this application?
    Thanks!

  2. #2
    Join Date
    Jun 2007
    Location
    Williams Lake, BC
    Posts
    3,247

    Default Re: Wiring Diagram Needed for SquareD QO Breaker Box

    What is your specific problem? Are these lights? If so you may have trouble getting QO circuit breakers small enough. I know they make 10A but locally only 15A are available...
    100% Off Grid @ 51* 46' N lat 124* 44' W long

    New House system: coming - 2 arrays @ 2240W
    CL150&Epanel 2 @140 W 12v PVs , 24V C&D AT-15P AGM @ 950Ah
    + CL150 2@120W 12 V panels, 24V C&D AT-15P AGM @ 950Ah
    Cotek ST1500W inverter, TBS 30a-24v Omni-charger, Honda Eu3000is,

    Guest cabin system: 3 - 70W panels to SB 2000e CC, with 2 - 100 ah 12v SAFT wet NiCd's , 600W TSW Inverter

  3. #3
    Join Date
    Jul 2007
    Location
    Quetico, Ontario
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    5,040

    Default Re: Wiring Diagram Needed for SquareD QO Breaker Box

    I used a QO box and breakers. It is pretty simple. Assuming it is a split phase panel, you can wire a jumper between the two hot buss lugs, if you choose not to use a main breaker. Then you bring the positive from the battery to one of the lugs. (fused at the battery as well). If you choose to use w main breaker, you can jump between both lugs of the main to energize the busses. Then install what ever branch circuits as desired, properly sized and wired. Energize the Breakers with the positive. Then return the negs to the neutral buss, while attaching the home run to the neutral lug on that buss, returning to the battery neg.

    Hope this helps,

    Tony

    Ps I would lable every end of every positive with red tape so that you don't get confused ns accidentally short a positive to a negative.

    T
    Please note, being a moderator does not add any weight to my opinions 300 watts Siemens/BP panels,plus a Sun 90,, making ~400. ~30 amps into Rogue MPT-3024, 450 ah of Trojan T-105, Morningstar ts300 inverter, a Tri-Metric meter.a collection of antique generators, plus 2 Honda eu-1000i's (also a BS2512 IX controller) and assorted other stuff!

  4. #4

    Default Re: Wiring Diagram Needed for SquareD QO Breaker Box

    Tony, I'm going to use a main breaker it is a 40 I will run my positive from battery to this breaker, and then can I use this same breaker to run to my charge controller or do I need a separate breaker? I have a jumper between both hot lugs that come in contact with the breakers. also on my neutral bus, do I just run a wire off my negative on my battery to the neutral bus lug? And furthermore I put a ground bus bar in my box and have run all the grounds to this including a ground wire out to a grounding rod, is it okay for this to be in the box? Also my Iota is wired to a 20 breaker in box does a wire need to run off this breaker to positve on battery or when I power up charger will it run back down through the box to the main breaker and down to battery?? Tony I really appreciate your help this is a long time coming and I am very excited to finally see this come to fruition...

  5. #5
    Join Date
    Jul 2007
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    Quetico, Ontario
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    5,040

    Default Re: Wiring Diagram Needed for SquareD QO Breaker Box

    First, don't forget a fuse at the battery, ideally something like a Bluesea terminal fuse.

    Next, I would not share the breaker with the PV. I would put the PV on it's own breaker(s) That way yuan [your can?] still energize your loads if you need to de energize the PV at any point. You can tie the negs to the neutral buss bar.

    The neutral Buss can be bonded to the ground buss, and then carry the grounds out to a single grounding rod. Be careful however not to mix DC grounds with AC grounds as you can induce ground loops that can wreak havoc on certain things, like electronic volt controllers on gennies. I am not a grounding expert, but I'm sure others will chime in if I am in error.

    As for running the Iota charge leads through the panel and but I would put it on its own breaker. By using the same "main" breaker, you run the risk of over current if the charger is putting out full current, the PV is putting it full current, and the loads are drawing current. Each charging source, and each load circuit needs to be independently breakered ( or fused) Personally, I would also consider fusing the output of the Iota directly at eh charger (if it doesn't have it's own fuse) as well as breakering it at the box.

    Good luck and keep in touch,

    Tony
    Please note, being a moderator does not add any weight to my opinions 300 watts Siemens/BP panels,plus a Sun 90,, making ~400. ~30 amps into Rogue MPT-3024, 450 ah of Trojan T-105, Morningstar ts300 inverter, a Tri-Metric meter.a collection of antique generators, plus 2 Honda eu-1000i's (also a BS2512 IX controller) and assorted other stuff!

  6. #6

    Default Re: Wiring Diagram Needed for SquareD QO Breaker Box

    so I decided to fuse my pos. run from battery to main lug instead of using a breaker. so now the charge controller has its own breaker. so not sure about this charger, you mentioned not to mix ac/dc grounds, is this what Im doing if my charger is run on ac and I have it tied into my ground bus in the box? How do I ground the charger if this is wrong? should I even have the charger on a breaker in my box and the neg. of charger tied into my neutral bus or is their another way of doing this? so its fine to bond the neutral bus to the ground bus should this wire be bare? If this setup for the Iota is correct, (by the way it does have its own fuse), do I need to run a wire off the Iotas breaker to the positve on battery or will it run power from charger to bat. through the main line connected to the hot lug? thankyou so much for your time and thought!

  7. #7

    Default Re: Wiring Diagram Needed for SquareD QO Breaker Box

    Quote Originally Posted by Crystal View Post
    so I decided to fuse my pos. run from battery to main lug instead of using a breaker. so now the charge controller has its own breaker. so not sure about this charger, you mentioned not to mix ac/dc grounds, is this what Im doing if my charger is run on ac and I have it tied into my ground bus in the box? How do I ground the charger if this is wrong? should I even have the charger on a breaker in my box and the neg. of charger tied into my neutral bus or is their another way of doing this? so its fine to bond the neutral bus to the ground bus should this wire be bare? If this setup for the Iota is correct, (by the way it does have its own fuse), do I need to run a wire off the Iotas breaker to the positve on battery or will it run power from charger to bat. through the main line connected to the hot lug? thankyou so much for your time and thought!
    your help will be greatly appreciated.

  8. #8
    Join Date
    Mar 2006
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    SF Bay Area (California)
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    Default Re: Wiring Diagram Needed for SquareD QO Breaker Box

    Every wire that leaves the common battery connection point should have a fuse/breaker for the rated load...

    For example a 14 awg wire should have a 15 amp fuse/breaker, a 12 awg wire should have a 20 amp breaker, and so on (if you are using the NEC requirements). For example, here is a basic chart on NEC vs fusing:

    Wire Current
    Ampacities NEC Table 310-16


    The NEC is pretty conservative in its ratings--So a good place to start. Also remember to "derate" your wiring for the loads.

    For example, if you have a 16 amp average load, then the wire/fuse minimum rating should be:
    • 16 amps * 1.25 NEC derating = 20 amp minimum fuse/breaker/wire awg


    Or if you have a 50 amp rated fuse/wiring, then the maximum continuous current would be:
    • 50 amps * 0.80 NEC derating = 40 amp maximum continuous load


    Every positive wire that leaves the common connection point (bus bar, breaker panel, etc.) should have such a fuse/breaker.

    And, since the battery is generally the largest source of current in the system--It would be a good idea to have a large fuse/breaker from the battery to the bus bar (100-400 amp or so, depending on the size of your wiring and your total loads/charging current). Something like the BlueSea Battery Terminal Fuse assembly (as Tony mentioned) is a simple solution there.

    -Bill
    20x BP 4175B panels (replacement) + Xantrex GT 3.3 inverter for 3kW Grid Tied system + Honda eu2000i Inverter/Generator for emergency backup.

  9. #9
    Join Date
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    Default Re: Wiring Diagram Needed for SquareD QO Breaker Box

    It gets more interesting with battery based applications because you ah e current source at multiple points. For example a wire between a battery and a battery charge, can be energied from the battery, but can also be energized from the charger, and ergo may need to be fused at both ends!

    Bottom line, you can seldom go wrong with too many or too small fuses, and size the fuses for the wire size, not the loads!

    Tony
    Please note, being a moderator does not add any weight to my opinions 300 watts Siemens/BP panels,plus a Sun 90,, making ~400. ~30 amps into Rogue MPT-3024, 450 ah of Trojan T-105, Morningstar ts300 inverter, a Tri-Metric meter.a collection of antique generators, plus 2 Honda eu-1000i's (also a BS2512 IX controller) and assorted other stuff!

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