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.
How can you be sure the piping has a solid electrical connection at the joints.? May 5, 2017 at 16:00
@Decapod basic care in assembly, common sense (e.g. don't reuse conduit that's been paimted), using the products according to their labeling and instructions, and periodic inspection of exposed areas. If you feel that is inadequate to your application, running a ground wire is correct, or the heavier IMC or rigid may suit better. May 5, 2017 at 16:39
The Dutch standard NEN 1010 prohibits this kind of installation. May 5, 2017 at 17:11
I hear they also prohibit wire nuts and backstabs. However, they do seem to allow construction on flood plains, so each to their own I suppose. May 9, 2017 at 15:01
Piping can be used for mechanical protection. The general rule is that everything should be double insulated. So if you use metal conduit you cant put single wires inside. A cable however is allowed. May 9, 2017 at 19:37