I have to run a dedicated circuit for an air compressor and I want to run to circuits interdependently to one outlet. that was I can use the empty receptacle for my light. I am an A/C sub so I know enough to install the new breaker, I just want to make sure that I run each circuit correctly.

First, on the outlet I need to break the tab on the hot side, but can I leave the tab on the common side?

Second, if I can leave the tab on the common side then can I run one 12/4 set, black to top, red to bottom, white to common, green or bare to ground?

Third, assuming that the above is correct, then one dual pole 20amp breaker should work, top-black, bottom-red (or brown, depending on the set, I have seen it both ways) with white to common and green to ground.

I only have enough room in the box for one more breaker so I am hoping that this can work, otherwise I will not have the use of the top half of this outlet.

If I cannot use a mutual common, then what would be the correct procedure?

Any help is greatly appreciated, thank you in advance for your help.

 

Welcome to the forums! You will be creating a MWBC, or multi wire branch circuit, which is perfectly fine. You will be using 12/3 with ground, or BRW&G THWN in conduit. The method you describe is correct. Leave the tab on the neutral (not common) side and attach your hots, one to one screw, break tab and the other to the other screw. Grounds are connected normally. Double 20 amp breaker. If this is a detached garage, your neutral buss and ground buss should be separated, so keep them that way.

 

I typo'd the 12/3, sorry about that one.

Thanks for the help.

 

If the receptacle is in an unfinished basement or the garage it will require GFI protection. If so you will need a 2 pole GFI breaker. A GFI receptacle cannot be split wired.