I have a 12/3 wire running to an outlet that controls two different things. The outlet is switched and has the black wire connected, while the white and ground wires are pigtailed together. There's a separate switch for another circuit using the red wire and a black pigtail from the same bundle—this connects to the porch light. I'm wondering if it's common practice to have this kind of setup, where both outlets are switched instead of having individual power lines. Shouldn't each 12/3 wire be dedicated to its own outlet or switch to prevent them from both being controlled together? I'm frustrated because I can't seem to fix it without more wiring.
1 Answer
What you're describing is known as a Multi-Wire Branch Circuit (MWBC). It can be safe if set up right, meaning the two breakers should be tied together to prevent overloading and must be on opposite busses in the panel. Check those connections to ensure everything's compliant. If they're correct, then it sounds like whoever set it up did a good job!
So just to confirm, if a single breaker controls both the light and switch, that might not fit the MWBC rules, right?