electricalgroundinggrounding-and-bonding
I have EMT leading to a metal junction box, and from that box goes plastic liquid tight to some equipment. Currently I have a ground conductor running all the way back to the panel, but I'm wondering if it's enough to terminate that ground at the metal junction box (so that the EMT back to the panel forms the remainder of the equipment ground).
Related question: how do I properly bond the 10 ga grounding conductor in the liquid tight to the metal box? Crimp a ring terminal on it?
I will do my best here. I take it the reason you are asking about using NM wire is to save money? Purchasing NM is much cheaper. You can still run NM inside the conduct if there is room left. So if your conduit is 3/4 inch. you maybe able to pull 14/2 wire through with Lube.
Your subpanel would need a separate ground bus since the conduct is considered the (Ground) By installing a Ground bus and using the NM 14/2 or 12/2 you must connect the Neutral and Ground separate as for the panel is not bonded. I believe the term is floating ground and neutral. Your Subpanel is connected to your Building since it is not Bonded. The question i have is why is your panel has only 1 bus bar? There should be 2 one for the Neutral and the other for the Ground. Your subpanel should have 1 Aluminum service line that contains 2 hots leads and 1 neutral and 1 ground. The other question i have is the service line coming from the Main Panel inside metal conduct as well? The gang boxes are grounded by the Conduct, but I would recommend you put a Pig Tail in the box.
Please see this answer, for more detail. Basically if you have equipment grounding conductors enter the box, you add 1 fill unit.
In the example you've provided you have 12 if it's a box without internal clamps, and 13 if it has internal clamps.
Current Carrying Conductors
Ungrounded (hot) 4
Grounded (neutral) 3
----------------------------------
7
Equipment Grounding Conductor 1
Clamps (maybe) 1
Devices 2
x2
----------------------------------
4
----------------------------------
Total 13
Best Answer
Yes, it's allowable to tie a ground wire to a junction box and let the metal conduit carry it the rest of the way back.
However, if the ground wire is already in the pipe, I'd leave it in there - belt and suspenders - unless you need the conduit fill.
You terminate a ground wire at a junction box by attaching it to a ground screw. Virtually all junction boxes have a hole tapped #10-32 specifically for ground screws, which are sold either with or without pigtails. You can put 1 wire on that screw, or any sensible number of ring terminals. Make sure the ring terminals are UL listed for use in mains power.