Does anybody know any tricks to prove whether a circuit is it home run or not?
Sure, if you have access to and test every possible receptacle/switch/light/equipment.
There are of course steps you can take to achieve this. Try not to assume anything though.
Today there was a circuit that was no longer needed that was a lot closer to the air handler I needed to wire than the panel was
In this case, turn off the circuit and test
every light and recep in the house. Check especially for hidden, added receps or ceiling fans. They will spin really fast for a short time. :jester
This happen often when changing a 120V AH circuit to a 240V circuit. Around here, the AH circuit is generally dedicated but you can't assume that someone, someday didn't tap it so, before we make the swap, we make damn certain that there is nothing else on it.