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Grid-Tie+Battery Hybrid System Install Done, Inspected, and Producing Power (cont'd)

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  • Grid-Tie+Battery Hybrid System Install Done, Inspected, and Producing Power (cont'd)

    (Continued from previous post due to image attachment limits. But you do want to see lots of pretty wiring pictures, don't you?)



    The battery cables are 4/0, plenty big enough. Conductor surfaces prepared with a Scotch-Brite pad (thanks, Sunking) and wiped clean with microfiber cloth, then torqued and later re-torqued to 10 N*m per manufacturer (Rolls-Surrette) specs. Because these are AGM batteries, they can be in the same enclosure with the rest of the equipment. And no messing around with sulphuric acid for me. I'll pay extra for that.




    This sub-panel also served as a pull box on the way to the critical loads panel and main panel, and as an AC disconnect for the critical loads wiring. The AC grid input wires just pass through. The solid-state relay is on the upper right. There's a spare two-pole breaker for a planned mini-split heat pump.

    The wires are 4 AWG, which was expensive, a challenge to pull, and overall a bit crazy. I could have gotten away with 6 AWG per code, though just barely. But you know what? The lights fed by my critical loads panel, which make a 240 ft. round trip from the service entrance to the Radian inverter and back again to the critical loads panel, do not flicker at all when someone turns the microwave oven on. I like low voltage drop.



    A pull box on my long and meandering way to the critical loads panel and service entrance. NEC requires 8" for 4 AWG wire, and you know what? It wouldn't work with anything smaller. The small wires are for the planned heat pump branching off from the previous sub-panel.



    At last, the critical loads sub-panel. Note the AC grid input conductors all nicely wrapped up in a plastic sleeve and feeding through this from the main panel (boring and not shown). Also note that my branch circuit EGCs are separated from neutral because this is a sub-panel.

    One more thing: The guy who built my house went crazy with his branch circuit wiring, dedicating 20A breakers and 12 AWG conductors to every little thing. (I seriously have an entire branch circuit and breaker for a light over my kitchen sink.) The blue connectors are a UL-listed way to combine two branch circuits onto one breaker.

    Because the big wires are 4 AWG, I didn't need them to be colored white for the neutrals. (Two hots and a neutral each for the AC grid in and AC inverter out.) Electrical tape took care of my color coding for me--white for the neutral of the AC grid in and grey (also NEC acceptable) for the neutral of the AC inverter out.

    Obligatory disclaimer: Although I know my way around electricity, I'm not a licensed electrician. I'm not giving you advice here about how to comply with applicable building codes or safety practices. But you knew that already.
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