Junkman
Well-known member
Was watching a youtube video this afternoon that someone sent to me to ask if it was correct. Starting at 4:40... Yes or no???
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Is this correct???
- Thread starter Junkman
- Start date
TRWham
Well-known member
Yes. It's called a multi-wire branch circuit (MWBC). Perfectly acceptable, though I am skeptical it makes fiscal sense given the cost of 12/2 vs 12/3 cable.
Terry D
Well-known member
The first example where he was wiring the 240 volt circuit is not a MWBC. There is no neutral, just 2 hots and a ground. He is just sharing one 240 volt circuit for two machines. I will say, I have never seen a NM-B cable with just a black, red and ground, it is still just a 12/2. The second example is a MWBC, since it has a neutral which carries the unbalanced load from two different 120 volt circuits from different legs. he used a 12/3 or 14/3
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TRWham
Well-known member
I only saw the 120 V receptacles at 4:40.
Terry D
Well-known member
I only saw the 120 V receptacles at 4:40.
Your right, I was just talking about the whole video. The second part is a MWBC
The first example where he was wiring the 240 volt circuit is not a MWBC. There is no neutral, just 2 hots and a ground. He is just sharing one 240 volt circuit for two machines. I will say, I have never seen a NM-B cable with just a black, red and ground, it is still just a 12/2. The second example is a MWBC, since it has a neutral which carries the unbalanced load from two different 120 volt circuits from different legs. he used a 12/3 or 14/3
I have not watched the video but by chance is the poster from Canada? That product seems to be a Canadian thing.
Terry D
Well-known member
I have not watched the video but by chance is the poster from Canada? That product seems to be a Canadian thing.
You are correct Norcal, I just looked the you tube channel up and he is from Canada
The video is correct, at least at the 4:40 mark. He does not get twice as much juice at that point. All he gets is a separate circuit. A two wire circuit is one circuit. A three wire circuit, in this case provides for two circuits. MWBC's are the most common method of wiring, in anything other than residential wiring. The biggest problem you find with them is when neutrals from other MWBC's get wired where they don't belong.
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exranger06
Well-known member
My house has a few MWBCs and I hate them. For one, you can't put arc fault or ground fault breakers on them. Just the cheap way of doing things. When I can, I run a separate wire and get rid of the MWBC.
You can use arc fault and ground fault breakers on MWBCs. You just have to use a double pole breaker.
nadogail
Well-known member
IMHO, it is correct enough.