grounding circuits for warehouse home runs


Senior Member
I am wiring a metal framed warehouse. It has an outdoor meterbase and panel box. The warehouse has a few wood framed offices. I plan to run the HVAC, and 20amp general lighting circuits from the outdoor panel box through EMT conduit to the office area. My largest circuit would be for the central heat. So a #6 is my largest wire. Above the office area I plan to put a splice box where I would convert from the emt conduit, and thhn wire to romex.
Could I run a single #6 grounding wire through that same emt conduit from the panel box for the equipment grounding conductor, or would I need to run an individual grounding wire for each circuit from the panel box.


Senior Member
you only need to run and size a ground wire for the largest ampacity. also you don't need a wire ground with EMT.


EC, Westchester, New York NEC: 2014
What I would do is drill & tap for a ground lug in the back of box for your #6 from the heat. Then another lug for a #12 pigtail, or just a #12 pigtail with a green ground screw, then wire nut all your #12 grounds to it. No need to pull a separate ground.



Staff member
If a #6 is the largest ungrounded circuit conductor you might only need a #10 EGC. Look at Table 250.122.