AC Safety Quick Disconnect between Inverter and Solar Meter wiring

I'm confused.

I have an AC disconnect between the AC output of the Inverter and the Solar Meter installed by APS.  That solar Meter then feeds two breakers in my main box.  This is a new install and getting approved by APS

Today, the APS guy came out and did a continuity check from the top lugs of the AC Safety Disconnect to the bottom lugs of the Solar Meter.  He said, those shouldn't have continuity.  I said, the output of the Inverter (AC) goes to the bottom lugs on the disconnect and the top lugs of the disconnect go to the meter.  Of course you will have continuity between the top lugs of the disconnect and the bottom lugs of the meter, that's the point.  THe circuit, between the inverter and the meter however is broken.

I took my continuity checker and showed the output of the Inverter does not have continuity with the Solar Meter when the switch is in the OFF position, the circuit isn't closed.

The APS guy again said, the top lugs of the disconnect should not have continuity with the bottom lugs of the meter.  I then said, well, if I swap the wires in the disconnect, the the top lugs of the disconnect will then go to the inverter and the bottom lugs of the disconnect go to the Solar Meter and then the bottom lugs would have continuity so what the hell is the difference if continuity is between the top or bottom lugs as long as the circuit between the inverter and the Solar Meter is broken when the disconnect is in the off position?

The ONLY think I can see is that the top of the disconnect is labeled "LINE" and the bottom of the disconnect is labeled "LOAD"  I've read quite a bit that LOAD should go to inverter, however, the APS guy said LOAD should go to the Solar Meter.

As far as a circuit is concerned as long as the lugs at the top and bottom of the switch are disconnected, the circuit is broken.  But, the top lugs of the disconnect are marked "LINE" so I would think their thought is LINE should be INVERTER and not the Meter.  The circuit doesn't care, but, it's more of a semantics thing.

So, I said, if I swap the wires in the Disconnect so the top lugs of the disconnect go to the inverter and the bottom lugs of the disconnect go to the Solar Meter, then everything is ok.  He said "Yes".

Ok, I'm so frustrated, what the F*!* difference does it make on a quick disconnect as long as the circuit is broken?  IF I painted over those little "LINE" and "LOAD" stamps on the metal box, nothing changes.  I just don't get it.


  • BB.BB. Super Moderators, Administrators Posts: 31,784 admin
    edited January 29 #2
    I agree with your reading of the line/load labeling and where to connect the Utility Power (line) and the GT inverter (load)... 

    Generally, I would want to pull the disconnect, and the moving parts (typically load) would be "electrically dead"--Disconnect GT inverter from Line, the GT inverter cannot generate voltage/current so the moving parts are "electrically dead" and will not shock anyone.

    However the APS guy is "stuck" in the source of power/energy (the GT inverter) and the power going to the Grid (sort of the "load" in this scenario). I think he is wrong--But sometimes if you can simply rewire and get their approval, then just do it. And if it bothers you--Later rewire to the "correct" method. Does the disconnect go directly to the meter or to the main breaker panel? If to the main breaker panel, you can turn off the "GT Solar breaker" and rewire easily and safely. If the disconnect goes directly to the meter (should not--But who knows how APS requires there connections)--You would have to pull the meter and have it resealed to rewire (should not be an issue--I have pulled meters to do work on my home--Just called my local utility to reseal down when I was done).

    I just went out to my solar disconnect (installed 10+ years ago--Today, GT Solar disconnect switches are no longer required by my northern California Utility--PG&E--Olden days, utility required GT disconnect or they would pull your meter to disconnect gt solar inverter when lineman was working on service--Today they agree that GT Inverters shutdown safely when utility power is cut), and it is wired with Line to Utility Power, and Load to GT inverter output). My disconnect "Line" connects to Utility Power; and "Load" connects to GT Inverter AC output as wired by the original installer [added clarification. -BB]

    I am not sure that our inspectors ever checked the Line vs Load side connection for the GT Inverter. But in any case, either should disconnect "safely" (ignoring that all the "metal" of the switch is still "hot" with utility connected to load side of disconnect).

    Just as an aside, Many DC breakers (especially older ones) are very much polarity sensitive--If you connect the breaker "backwards", the reverse DC current flow can cause a sustained arc inside the circuit breaker and start a fire very easily (DC Arcs are much more "difficult" to "quench" vs AC Arcs--Breakers and switches have to be designed to properly direct the Arc into the suppression channels). DC arcs can be directed with a magnet--Which is polarity sensitive--Right way, the arc is "blown" into the arc suppression area. Backwards, the arc is pulled in the breaker's guts and continues to arc and start a fire. Also, there can be "correct breaker orientation" (hot arc rises into channels... upside down, arc "rises" into the "wrong" area).

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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