For those of you who like receptacle stabs

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I think you need to reread the OP. It said there was 12/3 BX feeding to a junction box. The neutral terminals of the back-stabbed receptacle served as the common point for several multi-wire branch circuits.

I did read it and nowhere in the OP was it clear that the circuit TO the junction box is served by TWO different circuit breakers on TWO different legs eg. L1 AND L2. 12/3 RX wire is unknown to me and you're generously allow for a typo. As I pointed out the three wires could be serving Phase, Neutral and Ground. There were TWO circuits leaving from that point on, and the OP called those MWBC but unless there were two different legs involved in the feeder to the JB then that description is inaccurate.

The description was almost as incomplete as one would read a newspaper articles description of an overstated case because of the lack of understanding on the journos part, not an accurate description by a professional.

Sorry for for pointing out that accuracy is an essential part of communication and unambiguity is not unlike cleanliness.:happysad:
 

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
Because 300.13(B) doesn't allow it.:happyno:
Understood. But, just because the sign in a restaurant's restroom says "Employees must wash hands" doesn't mean they will. Unless an inspector inspects that JB either during the rough or at the final to pick up on that violation then 300.13(B) doesn't exist (technically)
 

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
The OP complains about shoddy installation practices and then suggests another code violation as a remedy.

Classic.
Sorry Cow, I didn't mean to suggest that I would commit such a heinous crime:happyno:. What I was inferring was that if someone were of the frame of mind to wire a MWBC without splicing the neutrals through the least they could do is wire it so that the chances of the feed neutral separating from the outgoing neutrals would be slim. But now, the more I think about it whoever wired this didn't give a crap anyway so why would they think that way:?
 

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
I am just wondering how the alleged loose wires caused the equipment damage?
If the feed neutral of the MWBC comes apart from the junction point (in this case at that first receptacle) and the outgoing neutrals to each of the opposing phased circuits are still tied together, then phase 1 feeds from the breaker panel, goes out through an appliance (lets say the refrigerator motor for example) and seeks a return path through its own neutral, comes to the defective junction point and sees no return path to the breaker panel via the MWBC neutral, then goes out through the neutral of circuit 2 (lets say the microwave) and back to phase 2. At that point there will be something close to 240 VAC running through the appliances. Anything on these kitchen circuits that requires 120VAC constantly (like digital displays) are toast.
 

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
I did read it and nowhere in the OP was it clear that the circuit TO the junction box is served by TWO different circuit breakers on TWO different legs eg. L1 AND L2. 12/3 RX wire is unknown to me and you're generously allow for a typo. As I pointed out the three wires could be serving Phase, Neutral and Ground. There were TWO circuits leaving from that point on, and the OP called those MWBC but unless there were two different legs involved in the feeder to the JB then that description is inaccurate.
Judging from the amount of posts you have it looks as though you've been around here for a while. By now you should have known or realized that MWBC is short for multiwire branch circuit. If you've been in the trade even the shortest amount of time you would know that a MWBC shares a neutral with two opposing phase single phase circuits (or 3 in the case of 3 phase systems).
The description was almost as incomplete as one would read a newspaper articles description of an overstated case because of the lack of understanding on the journos part, not an accurate description by a professional.
Yes, you are correct, I did not explain what a MWBC was but I was under the impression that we here in the forum are all either in the trade or related to the trade in some form or another. We've been discussing MWBC's since the forum was established and quite frankly I'm a bit taken back that there are still some here that don't know what they are.
Sorry for for pointing out that accuracy is an essential part of communication and unambiguity is not unlike cleanliness.:happysad:
I mean this respectfully my friend, I think it is you who needs the education in effective communication and not me.:happyyes:
 

Cow

Senior Member
Location
Eastern Oregon
Occupation
Electrician
I did read it and nowhere in the OP was it clear that the circuit TO the junction box is served by TWO different circuit breakers on TWO different legs eg. L1 AND L2. 12/3 RX wire is unknown to me and you're generously allow for a typo. As I pointed out the three wires could be serving Phase, Neutral and Ground. There were TWO circuits leaving from that point on, and the OP called those MWBC but unless there were two different legs involved in the feeder to the JB then that description is inaccurate.

The description was almost as incomplete as one would read a newspaper articles description of an overstated case because of the lack of understanding on the journos part, not an accurate description by a professional.

Sorry for for pointing out that accuracy is an essential part of communication and unambiguity is not unlike cleanliness.:happysad:

Anyone on here who is actually an electrician knew what the OP meant. Rather than admitting you just didn't know because you're not familiar with the topic at hand you'd rather type several paragraphs explaining why you think the description was insufficient when all along everyone knew what he was talking about. Except you. Good grief. :roll:
 
Anyone on here who is actually an electrician knew what the OP meant. Rather than admitting you just didn't know because you're not familiar with the topic at hand you'd rather type several paragraphs explaining why you think the description was insufficient when all along everyone knew what he was talking about. Except you. Good grief. :roll:

Excuuuuuse me!!!!!!:happyno:
  1. I did not know that this forum is restricted to electricians.
  2. Could you explain to me what RX wire is?
  3. Should the OP phrased that the 12/3 ORIGINATED as an MWBC and not only labeling it as such AFTER it is leaving the junction box would have cleared things up.
  4. Oh I am sure that just me, the dumb engineer, who did not understood this highly accurate and descriptive soliloquy.
 

JES2727

Senior Member
Location
NJ
  1. Could you explain to me what RX wire is?
  2. Should the OP phrased that the 12/3 ORIGINATED as an MWBC and not only labeling it as such AFTER it is leaving the junction box would have cleared things up.
Weressl,

RX is, presumably, romex. It's not an abbreviation I use, but I'm pretty sure that's what he's referring to.
The '3' in 12/3 refers to the current-carrying conductors. The 3 wires would be black, red, and white. The bare ground is not included in the count.(Unless you're buying rubber cord. 12/3 SJ would be black, white, and green. I don't know why...) Those of us that work with these materials every day understand that if you're installing 12/3 romex it is most likely a MWBC.

I hope this helps clear it up for you.
 
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
Those that keep track will be able to tell us when, but it wasn't all that long ago we could use MWBC to each kitchen duplex receptacle. One duplex could satisfy the need for 2 circuits to a small kitchen counter top. We were not forced to tail out the neutral, nor were we reguired to use handle ties or 2 pole breakers. Back stabbing was a legal and accepted practice.

Multiple neutrals were installed in one hole. Just the way it was done. That change wasn't all that long ago either.


Read it again, the installers were weinies and just didn't torque the screws to the first click of the wrist.
 
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Weressl,

RX is, presumably, romex. It's not an abbreviation I use, but I'm pretty sure that's what he's referring to.
The '3' in 12/3 refers to the current-carrying conductors. The 3 wires would be black, red, and white. The bare ground is not included in the count.(Unless you're buying rubber cord. 12/3 SJ would be black, white, and green. I don't know why...) Those of us that work with these materials every day understand that if you're installing 12/3 romex it is most likely a MWBC.

I hope this helps clear it up for you.

  1. Don't deal with presumptions. Deal - not happily - with designations provided in the NEC.
  2. That would be 3#12+G on any drawing that I sign, indicating the ground size ONLY if it is different than the main conductors.
 

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
Those that keep track will be able to tell us when, but it wasn't all that long ago we could use MWBC to each kitchen duplex receptacle. One duplex could satisfy the need for 2 circuits to a small kitchen counter top. We were not forced to tail out the neutral, nor were we reguired to use handle ties or 2 pole breakers. Back stabbing was a legal and accepted practice.
You are correct. What has changed is that the receptacle mfr's now make receptacles so that the stab holes will only accept 14 ga. wire (go figure - like that makes a difference).
 

hurk27

Senior Member
Those that keep track will be able to tell us when, but it wasn't all that long ago we could use MWBC to each kitchen duplex receptacle. One duplex could satisfy the need for 2 circuits to a small kitchen counter top. We were not forced to tail out the neutral, nor were we reguired to use handle ties or 2 pole breakers. Back stabbing was a legal and accepted practice.

Multiple neutrals were installed in one hole. Just the way it was done. That change wasn't all that long ago either.


Read it again, the installers were weinies and just didn't torque the screws to the first click of the wrist.

as to the above in red, it's been a code requirement for a while, maybe it wasn't called out in your area, but here its been required as long as I can remember?

Heres from the 1999 NEC:
300-13(b) Device Removal. In multiwire branch circuits, the continuity of a grounded conductor shall not depend on device connections such as lampholders, receptacles, etc., where the removal of such devices would interrupt the continuity.

Not sure when it was put into the code?
 
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GeorgeB

ElectroHydraulics engineer (retired)
Location
Greenville SC
Occupation
Retired
  1. Don't deal with presumptions. Deal - not happily - with designations provided in the NEC.
  2. That would be 3#12+G on any drawing that I sign, indicating the ground size ONLY if it is different than the main conductors.
NEC designation is NM, non-metallic sheathed cable. Romex(r) is Southwire's trademarked brand of it. I don't know if the deep-link works, but try http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheet6. From that,

Southwire's Romex SIMpull? Type NM-B (nonmetallic-sheathed cable) may be used for both exposed and concealed work in normally dry locations at temperatures not to exceed 90?C (with ampacity limited to that for 60?C conductors) as specified in the 2011 National Electrical Code. NM-B cable is primarily used in residential wiring as branch circuits for outlets, switches, and other loads. NM-B cable may be run in air voids of masonry block or tile walls where such walls are not wet or damp locations. Voltage rating for NM-B cable is 600 volts.

I'm accustomed to your designation when individual conductors are pulled. BUT ... with yours, I'd expect 3 black wires and 3 phase ... how is Black/Red/White/Green noted?
 

growler

Senior Member
Location
Atlanta,GA
Multiple neutrals were installed in one hole. Just the way it was done. That change wasn't all that long ago either.


Read it again, the installers were weinies and just didn't torque the screws to the first click of the wrist.

Sure, even when they pig tail if they don't make a good connection and leave the wire nut loose you get the same problem.

I have seen a lot of open neutrals just because a wire slipped from under the wire nut. That's why I do the old school method and twist conductors to make a good connection and then install the wire nut.

But after 15-20 years since the install there may have been other tampering with the original install ( changing the receptacle or whatever).
 

gndrod

Senior Member
Location
Ca and Wa
Sure, even when they pig tail if they don't make a good connection and leave the wire nut loose you get the same problem.

I have seen a lot of open neutrals just because a wire slipped from under the wire nut. That's why I do the old school method and twist conductors to make a good connection and then install the wire nut.

But after 15-20 years since the install there may have been other tampering with the original install ( changing the receptacle or whatever).

Pre-twist worked for me even after 40 years.
 

realolman

Senior Member
you guys are trying to open up another can of worms...

to pre or not to pre..... that is the question.

I will stick my two cents in: If you skin the conductors longer than is necessary, bundle them all up where the top of the bare conductors are even , twist them together with a pair of pliers , and cut off the excess length, and then put on a wire nut....You can see what it's gonna look like before you put on the wire nut.

I don't see how you could make a better connection with a wire nut. I feel I will find out shortly:)

I have sort of a side question. I installed a light fixture the other day where the instructions said to tape the wirenuts.... If the manufacturer' s instructions tell you to do that, are you supposed to do that?
 
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