Multi-wire Branch Circuits

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Jimmy7

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Boston, MA
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Electrician
I have a question about an existing 120v 20 amp mult-wire branch circuit in a single family residence. The circuit is fed from two 20 amp two single pole breakers with no breaker tie with a 12-3 romex. The 12-3 romex then goes into the first single gang box where the red wire and white wire are backstabed on the receptacle. There is also 12-2 romex that terminates in this box and then goes to another outlet receptacle. The black of the 12-3 and the black of the 12-2 are spliced together, and the white of 12-2 is backstabbed on the receptacle as well.

1. I don’t like backstabbing receptacles, and think the white wires should be spliced with a pigtail to the neutral of the receptacle
2. Do the breakers need to be on different phases, and do they need a breaker tie? (Someone told me that you only need a breaker tie when the multiwire terminates on two yokes of a duplex receptacle, is that true?)
 
Jimmy7 said:
I have a question about an existing 120v 20 amp mult-wire branch circuit in a single family residence. The circuit is fed from two 20 amp two single pole breakers with no breaker tie with a 12-3 romex. The 12-3 romex then goes into the first single gang box where the red wire and white wire are backstabed on the receptacle. There is also 12-2 romex that terminates in this box and then goes to another outlet receptacle. The black of the 12-3 and the black of the 12-2 are spliced together, and the white of 12-2 is backstabbed on the receptacle as well.

1. I don’t like backstabbing receptacles, and think the white wires should be spliced with a pigtail to the neutral of the receptacle
2. Do the breakers need to be on different phases, and do they need a breaker tie? (Someone told me that you only need a breaker tie when the multiwire terminates on two yokes of a duplex receptacle, is that true?)
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NEC has required splicing neutral for at least 30 years if not more in situation like this. Can't remember exactly how it is worded but basically removal of the device can not interrupt continuity of the grounded conductor when it feeds on to other devices.

Handle tie wasn't always required though such requirement does go back even farther for when you are supplying both "circuits" to the same yoke. But since about 2005 or so all multiwire circuits regardless of conditions or location have required either handle ties or common trip breakers.

Each ungrounded conductor does need to be on different "phase". If not the neutral conductor is not carrying current imbalance it is carrying additive current. For 20 amps of load on each half of the circuit would end up making the neutral carry 40 amps if the two ungrounded were on same "phase"
 
1. Neutral should have a wirenut & pigtail to the receptacle
2. Definitely on different phases and handle tie required (210.4)
 
See 300.13(B) concerning the neutral through the device.
When the wiring was installed a handle tie may not have been necessary but in todays code it would be needed or a multi pole breaker.

BTW, a duplex receptacle is mounted on one yoke.
 
Stupid question.. If I install a handle tie, will both breakers trip okay if only one breaker senses a fault?
 
Jimmy7 said:
I have a question about an existing 120v 20 amp mult-wire branch circuit in a single family residence
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Joint and several liability makes touching any remodel, a legal exercise in hazard documentation, with dissected code violations, photos, and remaining defect disclosure for transfer on sales TOS.

There is no profit opening these cans of worms, without billing for the paperwork, which takes longer than field labor repairs.

Thats why most electricians are panel flippers that refuse to touch interior wiring.
 
ramsy said:
Joint and several liability makes touching any remodel, a legal exercise in hazard documentation, with dissected code violations, photos, and remaining defect disclosure for transfer on sales TOS.

There is no profit opening these cans of worms, without billing for the paperwork, which takes longer than field labor repairs.

Thats why most electricians are panel flippers that refuse to touch interior wiring.
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This is actually my mother-in-law’s home (Insert joke here), so I’m just trying to do the right thing.
Actually, I have one more question. If you change a service that has multi-wire circuits with no handle ties, do we need to install handle ties in the new panel?
 
ramsy said:
Joint and several liability makes touching any remodel, a legal exercise in hazard documentation, with dissected code violations, photos, and remaining defect disclosure for transfer on sales TOS.

There is no profit opening these cans of worms, without billing for the paperwork, which takes longer than field labor repairs.

Thats why most electricians are panel flippers that refuse to touch interior wiring.
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What on earth are you talking about? 🤔. Sounds about as ridiculous as the pub with no beer.
 
If this happens to be counter tops with gfi, you may have some other issues...
Even the old backstab stuff, i dont remember any accepting #12's unless you opened up the hole.
 
Are the 20A breakers full size or tandems and are they installed on the same side of the panel? If they are tandems, you are likely on the same side of the 240 and that's a serious problem. If they are full size and on the same side and next to each other, they are probably on different sides of the 240 and you are ok. The code required a handle tie at some point and is a good idea. At least for full size breakers, they make handle ties that will only trip the over current side, but if you shut off the breaker manually, they both get shut off.
 
This is why I filed my Public Inputs.
 

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Jimmy7 said:
do we need to install handle ties in the new panel?
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Yes, and if it takes 8000.hrs for the special-order parts delivery, and you fill out the owner builder Project Experience certification form, my state will give you a C 10 electrical license.
 
tthh said:
Are the 20A breakers full size or tandems and are they installed on the same side of the panel? If they are tandems, you are likely on the same side of the 240 and that's a serious problem. If they are full size and on the same side and next to each other, they are probably on different sides of the 240 and you are ok. The code required a handle tie at some point and is a good idea. At least for full size breakers, they make handle ties that will only trip the over current side, but if you shut off the breaker manually, they both get shut off.
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roger said:
Maybe maybe not but the real reason is for manually operating the breakers together, not common tripping.
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For as long as I remember, breakers have been required to have "trip free" operation, meaning that the breaker must open when the load conditions require it, even when the operating handle is forced to stay in the ON position.
Two adjacent breakers which are not part of a common assembly will not implement a "common trip" condition where both open if one senses a a fault, even if they are connected by a handle tie. The common trip function cannot be implemented by something external to the breaker(s).
 
GoldDigger said:
For as long as I remember, breakers have been required to have "trip free" operation, meaning that the breaker must open when the load conditions require it, even when the operating handle is forced to stay in the ON position.
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Correct, which is the reason we are allowed to lock breakers in the closed position with a add on device.

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