Faulty AC Disconnect? You guys ever seen that happen?

HX_Guy
HX_Guy Solar Expert Posts: 296 ✭✭✭✭✭✭
in Solar Beginners Corner #1
Trying to trace why the inverter and meter are not getting power and it seems the problem is the AC Disconnect, though I can't for the life figure how this would go bad.

The top wires are coming from the main panel and I get a reading of 241v on the top two terminals. With the disconnect in the ON position, the bottom either reads 0V or fluctuates all over the places from 0...10...43...7. Seems all the disconnect should do is snap the bars into place when it's turned to the ON position, and the bars do snap in and visually look like they are making good contact.

Anyone ever run into this before?

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  • HX_Guy
    HX_Guy Solar Expert Posts: 296 ✭✭✭✭✭✭
    #2
    Re: Faulty AC Disconnect? You guys ever seen that happen?

    Problem ended up being the top left "clamp" was too far spread apart, bent it inward a bit and all is working.
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  • DanS26
    DanS26 Solar Expert Posts: 269 ✭✭✭
    #3
    Re: Faulty AC Disconnect? You guys ever seen that happen?

    Can't tell for sure, but it looks like heat damage in that switch.
    I would return for replacement....defective manufacturing.


    Man...you seem to be snake bit on this project. Hope you run the next ten years problem free because you sure have paid your dues up front.
    23.16kW Kyocera panels; 2 Fronius 7.5kW inverters; Nyle hot water; Steffes ETS; Great Lakes RO; Generac 10kW w/ATS, TED Pro System monitoring
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  • HX_Guy
    HX_Guy Solar Expert Posts: 296 ✭✭✭✭✭✭
    #4
    Re: Faulty AC Disconnect? You guys ever seen that happen?
    DanS26 wrote: »
    Can't tell for sure, but it looks like heat damage in that switch.
    I would return for replacement....defective manufacturing.


    Man...you seem to be snake bit non this project. Hope you run the next ten years problem free because you sure have paid your dues up front.

    Where are you seeing the heat damage Dan? Want to make sure and verify it if I can.
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  • DanS26
    DanS26 Solar Expert Posts: 269 ✭✭✭
    #5
    Re: Faulty AC Disconnect? You guys ever seen that happen?
    HX_Guy wrote: »
    Where are you seeing the heat damage Dan? Want to make sure and verify it if I can.

    Right under under the left hand lug, unless that is dielectric grease. If it is only grease then you are OK.
    23.16kW Kyocera panels; 2 Fronius 7.5kW inverters; Nyle hot water; Steffes ETS; Great Lakes RO; Generac 10kW w/ATS, TED Pro System monitoring
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  • HX_Guy
    HX_Guy Solar Expert Posts: 296 ✭✭✭✭✭✭
    #6
    Re: Faulty AC Disconnect? You guys ever seen that happen?

    Ah yeah, it's just grease. :)
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  • solarix
    solarix Solar Expert Posts: 713 ✭✭
    #7
    Re: Faulty AC Disconnect? You guys ever seen that happen?

    btw, that box is not grounded. First thing inspectors look for. The lug on the conduit bushing is just for the conduit. The box needs one too. Should be a self tapping, green screw into one of the little holes in the back of the box.
    And if you are relying on the equipment ground to also serve as the grounding electrode conductor (from the inverter to a irreversibly crimp to the ground rod, then you have to bond both ends of any conduit the GEC runs through. That means pulling the wire out and adding more bond bushings.
    Your installer doesn't know Jack (the inspector)
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  • HX_Guy
    HX_Guy Solar Expert Posts: 296 ✭✭✭✭✭✭
    #8
    Re: Faulty AC Disconnect? You guys ever seen that happen?

    Thanks Solarix. The ungrounded disconnect was also pointed out on another solar forum. Just to make sure I do it right, I can take a green 8awg cable and connect one end with a green, self tapping screw to a hole in the back of the box and the other end to the lug on the conduit bushing?

    For the inverter grounding, the installer ran a 6awg bare copper wire, exposed (not in conduit) to the GEC...is that the correct way?
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  • solarix
    solarix Solar Expert Posts: 713 ✭✭
    #9
    Re: Faulty AC Disconnect? You guys ever seen that happen?

    yes, just a jumper wire is sufficient - you might have trouble getting two #8's into the lug though. The jumper could be #10 solid. There is some question as whether these lay-in lugs are listed for "double-lugging" - that is joining two wires, but never had an inspector pull that one though. The external GEC sounds good.
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #10
    Re: Faulty AC Disconnect? You guys ever seen that happen?
    solarix wrote: »
    yes, just a jumper wire is sufficient - you might have trouble getting two #8's into the lug though. The jumper could be #10 solid. There is some question as whether these lay-in lugs are listed for "double-lugging" - that is joining two wires, but never had an inspector pull that one though. The external GEC sounds good.

    My inspector pulled the double lug problem and required a separate bolt in ground lug bar. Grounding was the biggest issue with the permitting on my system, took 3 trips by the inspector.

    My AC disconnect is troublesome as well. It needs to be slammed home to get the proper connections. My issue is APS put a lock on the disconnect, you cant just open the box and push the connection together.
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #11
    Re: Faulty AC Disconnect? You guys ever seen that happen?
    HX_Guy wrote: »
    Thanks Solarix. The ungrounded disconnect was also pointed out on another solar forum. Just to make sure I do it right, I can take a green 8awg cable and connect one end with a green, self tapping screw to a hole in the back of the box and the other end to the lug on the conduit bushing?

    For the inverter grounding, the installer ran a 6awg bare copper wire, exposed (not in conduit) to the GEC...is that the correct way?
    I don't think you can put two conductors in that ground lug. You might have to add a ground bar to the switch and run your ground wires into it and to the bushing lug.
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  • HX_Guy
    HX_Guy Solar Expert Posts: 296 ✭✭✭✭✭✭
    #12
    Re: Faulty AC Disconnect? You guys ever seen that happen?

    How does this look? Good to go?

    Used a 8AWG bare copper wire, scratched off a bit of the paint inside for a good bond, and used the same grounding lug. It looks good to me, but I have no experience with this.

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #13
    Re: Faulty AC Disconnect? You guys ever seen that happen?

    That may not pass inspection... There should have been a ground symbol of some sort next to the screw hole:

    Attachment not found.

    And there is a specific ground screw:

    Attachment not found.

    Will your inspector say anything--I have not clue.

    -Bill "not a licensed electrician" B.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • fire88
    fire88 Registered Users, Users Awaiting Email Confirmation Posts: 1 ✭
    edited June 2022 #14
    shouldn't you have install a neutral bar???
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #15
    Welcome to the forum Fire88,

    Most GT Inverters are 240 VAC single phase (for North America use in homes). They don't need/connect to any neutral wiring/bus bar.

    There are some that do connect to a neutral--It appears to have been added for safety--Basically the Neutral connection is used to measure the voltage between L1 and N (or L1 and L2 vs Neutral).

    There are some relatively common connection failures from Neutral on the pole transformer and Neutral in the home. Ideally, should measure Lx to N ~ 120 VAC. If there is a bad neutral connection somewhere, the L1 and L2 will not be 120 VAC to neutral. I.e., a heavy load on L1 will "collapse" the N voltage to below 120 VAC, and then L2 to N voltage will be > 120 VAC.

    You can see this in your home... For example the refrigerator starting will have some lights flicker dim (on same circuit as fridge) and other lights flicker bright (on other circuit).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #16
    I'm looking specifically at the top right screw connector.  Several wire strands are not going into their orifice.

    That reduces ampacity and increases heating.  And when they break off and fall ????

      Several other wires look oddly spread, I can't tell if the setscrew has spread them or the wire is fanned out too wide
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  • Wheelman55
    Wheelman55 Registered Users Posts: 243 ✭✭✭
    #17
    OP. Per Mike’s observation…I use these tin plated copper sleeves when I’m working with stranded wire. Buy the smallest size that will fit over your bare wire. 

    These sleeves make for a very secure connection, and will eliminate the issues that Mike pointed out. 

    BTW, these are replacement sleeves for the Polaris Grey 600 volt connectors. 


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