Argh this has had me running in loops all afternoon...
I have a single 120V 20A circuit for some exterior lighting.
Ensuring my voltage drop for this branch circuit is below 3%, I've upsized the conductors to #8 from #12.
Rather than just throw down (3)#8 on my plans for the circuit, I check Table 250.122 and see that equipment grounds are baseed only on the circuit overcurrent device, so that would initially lead me to use (2)#8 with (1)#12 ground.
I settle on (2)#8 with a #12G, but the problem grows in my mind like a bad itch...
... Won't the grounding conducter, if it's being used in a fault situation, be subject to the same voltage drop back to the grounding system? Does that voltage drop in excess of 3% mean the stray current will want to find an alternate path, or will the energy just dissipate more as heat on it's way to the grounding system?
My usual practice has been to match branch circuit grounding conductors to their VD-upsized partners, but now I'm all topsy-turvy on this issue...
In the process of trying to find a solution, I noted that #8's are what are normally used for 40A circuits before voltage drops are considered (T310.16), and a 40A circuit requires a #10G (T250.122)... Would this be the correct value if a #12 ground is no good?
Thanks in advance!