Do I need to run a ground wire with conduit? I have installed a line of lights using 1/2 EMT and tied into another circuit that is grounded coming off the panel. There are about 7 lights in a back room at my business. In addition, should the last light in the circuit feed back to the panel? The lights are just for supplemental lighting in the work areas.
Not if you don't want to. The EMT piping is itself a valid ground path, provided there is a ground path that is continuous back to the panel. All my work is in EMT and I don't own any green wire.
If you need to bond from the EMT to a ground wire, most likely there is a hole tapped for a 10-32 screw on the metal junction box, it may be sitting up on a pucker to give the ground screw some clearance.
UK-style "ring circuits" are illegal in the United States and the wiring of the circuit should not be looped back to the panel.
Sometimes conduit winds up being laid in a ring simply out of coincidence but the wires inside do not go in a loop.