Can someone, anyone help me better understand multi wire branch circuits? This panel I inspected today shown in picture had a 3 wire circuit feeding two breakers in the panel. Both feeding 20 amp breakers. Tried to trace this circuit but lost it…labeled dining room. If I’m correct this is acceptable no…should be 2 pole breaker or the singles should have handles tied together?
Sorry about the flipped picture!!
Yes, since it’s a MWBC sharing a neutral the two single pole CB’s need to be handle tied together or replaced with a 2 pole CB. This NEC requirement is relatively new (2008 NEC) so older panels didn’t need to meet the requirement when they were originally installed.
OK, just to be clear, I’m not trying to look smart or tell anyone how to do their job. This is a legitimate question so I can be sure I am not misunderstanding a key point.
The use of two energized conductors fed into a single lug on a breaker (as seen in the OP’s photo), constitutes a double-tap at the breaker, and should be called out on the report as a deficiency, correct?
If any part of the above statement is not correct, please explain to me why. Again, just trying to identify and plug holes in my knowledge here.
I know that some breakers are designed to do this safely, but this does not appear to me to be one of them.
I saw the double-tap and didn’t realize the forum is run like a quiz show What I don’t see (and if you can help me please do) anything that indicates a multiwire branch circuit is run. The red wire? I guess if you could trace it to a 12/3 NM cable - but I don’t see that in the pic. I mean we can only partly see one grounded bus so I can’t count the neutrals, so what evidence (from the pic) is there that the two 20 amp circuits share a neutral? Curious minds want to know.
If there is cable like NM then a two wire cable will be Blk/Wht and a three wire will be Blk/Wht/Red. Four wire cable could be Blk/Wht/Red/Blu or Blk/Wht-Red/Wht.
You would need to trace the conductors back to where they enter the panel to see what type of cable you have and if it’s actually setup as a MWBC. If it is then the two circuits need to be on opposite “phases” and if under the 2008 or later NEC the circuits need to terminate on handle tied single pole CB’s or a multi-pole CB.