(03-03-2021, 01:04 PM)Eurekan Wrote: One additional suggestion for you. Hopscotch your circuits along a wall. Space them about 3 ft apart and alternate the circuits. If you run multi heavy duty systems simultaneously this will keep you from blowing the circuit. You can use a common common as long as they are on alternate legs. (I think)
TDKPE has already explained the mechanics of using a mwbc. But, additionally, no matter the circuit type you can certainly share the ground conductor.
In fact, since you are using emt, make sure all your set screws are snug, then snug them again . If you properly ground the first box (or if it is securely grounded at the panel) , you can use the conduit as your ground. Tests have shown properly assembled metallic raceways have less resistance than the NEC required size ground conductor.
Then, by using the approved surface cover plate for your devices, you are allowed to use the cover plate as your grounding connection, eliminating the need for any green or bare grounding conductors and the associated pigtails anywhere in your run.
Edit: For those interested and wondering what an approved cover looks like:
A. The cover must be flat where it connects to the box
B. The device must attach by at least two places
C. The attachment must be permanent or semi permanent. The NEC gives as examples rivets or screws with locknuts. Raco covers come with a small bag of #6 screws with serrated nuts/washers.
Check your outlets, too. Many come with approved nuts. If the strap/yoke screws are held captive by those plastic squares, remove them. Many outlets are moving to small spring wire to capture the strap screws.