So using my example above of two duplex outlets (4 individual outlets) in a 2-gang box, is that one or two yokes?
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Multiwire Branch Circuit?
- Thread starter BigE
- Start date
Terry D
Well-known member
2 yokesSo using my example above of two duplex outlets (4 individual outlets) in a 2-gang box, is that one or two yokes?
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Terry D
Well-known member
OK, what constitutes a single yoke? A web search (which is not the same as "code says" suggests the frame that holds the individual outlets in a duplex outlet is the yoke.
https://diy.stackexchange.com/questions/133104/what-is-a-yoke-in-nec-electrician-parlance
If I put two duplex outlets
https://www.homedepot.com/p/Leviton...-Outlet-White-10-Pack-M24-05320-WMP/100055784
in a plastic 2 gang box does that make all four outlets part of the same yoke? What if I the two duplex outlets in a metal box
Plastic box
https://www.homedepot.com/p/Carlon-...rical-Switch-and-Outlet-Box-B232ACP/202065285
metal
https://www.homedepot.com/p/Steel-C...re-Handy-Box-Case-of-8-2G4DV1234-8R/202590014
What I proposed was basically two duplex outlets in a common 2 gang box. If the box is the yoke then yes, these are a common yoke. If not then these are separate. I could certainly see why everything in a multi-gang box should be powered down at the same time.
My description however was ambiguous. It would have applied to the case where two single gang boxes were placed near one another which would them make them normal, independent circuits.
The box is not the yoke. It is the strap that houses the device. So if you have a duplex receptacle, which shares the yoke. And you have broken the tab(s) off and split the two electrically, and feed it with two separate circuits, then the two breakers need to handle tied together so both ungrounded conductors ( hots) can be disconnected simultaneously. This has been code for a long time
The box is not the yoke. It is the strap that houses the device. So if you have a duplex receptacle, which shares the yoke. And you have broken the tab(s) off and split the two electrically, and feed it with two separate circuits, then the two breakers need to handle tied together so both ungrounded conductors ( hots) can be disconnected simultaneously. This has been code for a long time
OK, the reason why I asked was in reference to this post
Ummm the breaker would need to be handle-tied since they share the same yoke.
I might not have been clear in my earlier post but that intent was two duplex outlets (2x a duplex outlet) in a 2-gang box. Each duplex outlet is fed by a different breaker-wire. The only thing they share is a common box. If I understand your answer, that would be two yokes, one for each duplex outlet and thus no need for a tiebar across the breakers. It would be treated the same as if they were in separate single gang boxes.
I might not have been clear in my earlier post but that intent was two duplex outlets (2x a duplex outlet) in a 2-gang box. Each duplex outlet is fed by a different breaker-wire. The only thing they share is a common box. If I understand your answer, that would be two yokes, one for each duplex outlet and thus no need for a tiebar across the breakers. It would be treated the same as if they were in separate single gang boxes.
That's correct. What you're describing is pretty common in commercial settings. Lets you have two different breakers available at the same box, which is useful if you have two high draw appliances or tools next to each other. My garage, basement shop, and sewing space are all wired like this for just this reason.
It's pretty common to wire these as MWBCs, which means you have three wires going into each box, instead of four. In that case, they have to be handle tied breakers (at least for installations post 2008 NEC). But they don't have to be, and in romex land, it's less common.
That's correct. What you're describing is pretty common in commercial settings. Lets you have two different breakers available at the same box, which is useful if you have two high draw appliances or tools next to each other. My garage, basement shop, and sewing space are all wired like this for just this reason.
It's pretty common to wire these as MWBCs, which means you have three wires going into each box, instead of four. In that case, they have to be handle tied breakers (at least for installations post 2008 NEC). But they don't have to be, and in romex land, it's less common.
But I was always thought the make sure the outlets are separated inside the box from each other. So in case you have to work on one circuit and only turn off the one break that way you don’t still have live wires open where you are working. Now that’s if the outlet was not in my own house personally I don’t care and the outlets being separate.
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Wouldn't the tied neutrals prevent you from pulling more than the 15A the breaker is rated for?Maybe the original owner was using two high draw tools/items in that location at the same time, and he needed more than just a single 15 amp circuit to run them due to tripping a single circuit.
Jim
But I was always thought the make sure the outlets are separated inside the box from each other. So in case you have to work on one circuit and only turn off the one break that way you don’t still have live wires open where you are working. Now that’s if the outlet was not in my own house personally I don’t care and the outlets being separate.
Keeping one circuit to a box is pretty standard DIY advise, in large part because DIY electricians get confused by anything that isn't just a black and white wire. In residential Romex-land, it's pretty straightforward to do this, as cables don't have to enter a box unless there's a termination for that cable in the box.
But in commercial work, it's harder, you have multi-gang light switch boxes where many circuits are switched, you have high draw loads that require their own circuit. The quality of the people working on this should be higher as well, and they're presumed to know to test things before assuming they're actually turned off.
Wouldn't the tied neutrals prevent you from pulling more than the 15A the breaker is rated for?
Yes... and no.
Yes, if the breaker sees more than 15A going through either L1 or L2 it should trip. But you could still use say 2, 12A space heaters (24A total) with an outlet like the OP had *if* L1 and L2 are on opposite legs then you can draw a total of 15A at 120V per leg out of the outlet (240V total, 15A total). If you think of this as DC wiring then you can think of it as the current from the +120V leg can either go to neutral or into the -120V leg. If the -leg has no load then the current returns via the neutral wire. If the -leg has a load exactly equal to the +leg then the current returns via the -leg (no current flows through the neutral). If their is a difference then some current returns via the neutral and some via the -leg. The important part is that no individual wire sees more than 15A.
If they are mistakenly wired so L1 and L2 are on the same phase then you have an issue. Now all the current returns via the neutral wire which has no over current protection. Thus 15A from L1 + 15A from L2 become 30A through the now overloaded neutral wire.
That makes sense to me. Perhaps that was why it was wired that way.Yes... and no.
Yes, if the breaker sees more than 15A going through either L1 or L2 it should trip. But you could still use say 2, 12A space heaters (24A total) with an outlet like the OP had *if* L1 and L2 are on opposite legs then you can draw a total of 15A at 120V per leg out of the outlet (240V total, 15A total). If you think of this as DC wiring then you can think of it as the current from the +120V leg can either go to neutral or into the -120V leg. If the -leg has no load then the current returns via the neutral wire. If the -leg has a load exactly equal to the +leg then the current returns via the -leg (no current flows through the neutral). If their is a difference then some current returns via the neutral and some via the -leg. The important part is that no individual wire sees more than 15A.
If they are mistakenly wired so L1 and L2 are on the same phase then you have an issue. Now all the current returns via the neutral wire which has no over current protection. Thus 15A from L1 + 15A from L2 become 30A through the now overloaded neutral wire.
It was suggested to me today that this could have been an accommodation for a window A/C unit since there is a window just a few feet away. However, I thought those we designed for either 240V or a standard household 120V outlet. Does that sound plausible?
wyliesdiesels
Well-known member
That makes sense to me. Perhaps that was why it was wired that way.
It was suggested to me today that this could have been an accommodation for a window A/C unit since there is a window just a few feet away. However, I thought those we designed for either 240V or a standard household 120V outlet. Does that sound plausible?
naw that wouldnt make sense.
a 240v outlet for a window shaker would be a single receptacle not a duplex because of the size of the LCDI and the space it takes up.