True, not switching ground. But of three wires from switchbox to inverter, ground could be one.
Alternatively, there is a toothed washer where socket head cap screw mechanically holds switchbox to inverter. But I'd rather only depend on those to ground incidental metal objects, like a cover. Not to complete the intentional fault-clearing (or safety ground) path between inverter and array.
With diode check and capacitor scales I think I've confirmed Red is PV+ and Black is PV-. But Orange has funny connections to red and black, also shows diode and capacitance.
For now, I've capped Orange, connected Red and Black to MC3 pigtails so they diode-check same as my "new" SB -41.
Orange is same gauge as Red and Black. Don't know what function would require 3rd wire for non-isolated PV array, except safety ground.
With AC connected to 120/240V split-phase + ground (twist-loc extension cord), DC connected to PV+/PV- + ground (UF & safety switch), I turned on AC first, DC second. Display says, "Electric Arc Detected" "Check DC Generator" "Please confirm by tapping"
So I knocked and I knocked, but no body home.
RTFM:
"8206
Electr. arc detected
Please confirm by tapping The inverter has detected an electric arc and was recommissioned after a disconnection. By tapping, you are confirming that you have repaired any possible damage to PV modules, cables or plugs in the PV system.
Corrective measures: •Tap on the display within ten seconds of the display message appearing in order to recommission the inverter."
So I gotta go back and cycle power, work faster this time.