oversized grounded conductor

[wyboy]

In older installations I sometimes see several #12 ungrounded conductors to a j box pulled with an oversized grounded conductor (not a multiwire branch circuit) landing in a neutral bar in the j box then running # 12 neutrals with the individual circuits. I can?t find a specific article in the code that disallows this. Any ideas?

 

[A/A Fuel GTX]

Wow......never seen that. Bizarre to say the least.

 

[dcspector]

Tom and wyboy almost sounds like the super neutral MC cable.

 

[A/A Fuel GTX]

Sure sounds like a great way to overload the neutral going back to the panel.

 

[roger]

It is specifically allowed in 225.7(B) and is not specifically prohibited anywhere else in the NEC.

Roger

 

[charlie b]

This doesn't sound right. But it may be that I simply do not understand the description of the installation. Is this what you are trying to describe:

• In the panelboard, you have some number of breakers, let us say six, from which you have 6 single ungrounded #12 AWG conductors going through the same conduit, to a junction box.
• In the same panelboard, you have one large grounded conductor, let us say it is #8 AWG, that connects to the panelboard's neutral bar, that travels through the same conduit as the 6 #12s, that enters the same junction box, and that is landed on a neutral bar within the j-box.
• From the j-box, you have six outgoing conduits going different directions, each with one of the #12 ungrounded conductors.
• Within the j-box, you have 6 grounded #12 conductors that are connected to the neutral bar, and one of these goes into each of the outgoing conduits.

I am certain that this would constitute a violation of 210.4. But if this is not what you mean, then please try to describe it again. A sketch would be useful.

 

[jap]

I have seen this also.
A 2" conduit run from a panel to a Junction Box with several Ungrounded Conductors and a 1/0 Neutral. The only difference in the one I witnessed is there was no neutral bar in the junction box. All of the individual #12 and #10 Neutrals were split bolted to the 1/0. There had to be at least 15 or 20 of them.

 

[charlie b]

It is specifically allowed in 225.7(B) . . . .

Please help me out here. I don't understand what 225.7(B) is talking about, and I don't see its relationship to the present question. :-?

 

[charlie b]

A 2" conduit run from a panel to a Junction Box with several Ungrounded Conductors and a 1/0 Neutral.

If you leave a 3-phase panel with three ungrounded and one grounded, you have a MWBC. If you leave the same panel with 4 or more ungrounded and only one grounded, you have a violation. Or am I missing something here (seems likely)? :-?

 

[augie47]

I have seen installations that wyboy describes on older installs. A half dozen or so branch circuits installed with a #6 (or so) grounded conductor to serve all.
It would appear the new requirements in 210.4(B) might make that a violation.

 

[Dennis Alwon]

If you leave a 3-phase panel with three ungrounded and one grounded, you have a MWBC. If you leave the same panel with 4 or more ungrounded and only one grounded, you have a violation. Or am I missing something here (seems likely)? :-?

I am not sure it is prohibited if the neutral is sized to carry the entire load of the circuits. I find this to be a terrible install but cannot find an article that disallows it. Since it is not a MWBC by definition then the disconnecting of all ungrounded conductors doe not enter into the equation.

 

[don_resqcapt19]

If you leave a 3-phase panel with three ungrounded and one grounded, you have a MWBC. If you leave the same panel with 4 or more ungrounded and only one grounded, you have a violation. Or am I missing something here (seems likely)? :-?

Charlie,
The installation would be something like this: Three #12s on 20 amp breakers and all of the breakers on the same phase. The #12s would be used with a #6 grounded conductor. There is nothing in the code that I am aware of that would prohibit this type of installation.

 

[macmikeman]

I have seen this also.
A 2" conduit run from a panel to a Junction Box with several Ungrounded Conductors and a 1/0 Neutral. The only difference in the one I witnessed is there was no neutral bar in the junction box. All of the individual #12 and #10 Neutrals were split bolted to the 1/0. There had to be at least 15 or 20 of them.

I bet I could find you a listing violation for that there split bolt at least.....:roll:

 

[jap]

The one I ran across was like this.

30 circuit Flush mount panel in the wall. 208/120v 3phase.
(1) 2" emt conduit coming out of the top of the panel into the cavity above the layin ceiling.
Conduit ran approx 50' to a 24x24x6 J-box mounted in the center of an office area.
Not sure of the # of ungrounded conductors in the 2" emt but there were at least 12 of them each landed on its own 20 amp breaker. They did not pull a neutral for 3 circuits or a neutral for each circuit, they ran a 1/0 thhn taped white from the panel to the junction box. from the junction box it was a spider web of 1/2" emt's going to various receptacles and fixtures with only a
#12 hot and #12 neutral in each of the 1/2" conduits.The hots were wirenutted to the individual ungrounded conductors coming form the panel and all of the neutrals were split bolted to the 1/0 Neutral pulled from the panel.

 

[charlie b]

I . . . cannot find an article that disallows it. Since it is not a MWBC by definition then . . . .

There is nothing in the code that I am aware of that would prohibit this type of installation.

It's tricky, but I think it is there.

210.2 explicitly states that, "Branch circuits shall comply with this article." The "article" is the entirety of 210, not just 210.2. Therefore, if a branch circuit is not built in the manner allowed within 210, it violates 210.

So, 210.2 tells me I can build something that fits the definition of "branch circuit." Then, in 210.4, it states that branch circuits shall be permitted as MWBCs. That tells me I can build something that fits the definition of a MWBC. Between these two, I infer that I can't build something, unless it fits one of those two definitions. Looking back at the definition of a branch circuit, I see that it uses the term "overcurrent protection device" in the singular.

Conclusion: If you have more than one OCPD, and if it is not a MWBC, then it violates 210.

 

[don_resqcapt19]

It's tricky, but I think it is there.

210.2 explicitly states that, "Branch circuits shall comply with this article." The "article" is the entirety of 210, not just 210.2. Therefore, if a branch circuit is not built in the manner allowed within 210, it violates 210.

So, 210.2 tells me I can build something that fits the definition of "branch circuit." Then, in 210.4, it states that branch circuits shall be permitted as MWBCs. That tells me I can build something that fits the definition of a MWBC. Between these two, I infer that I can't build something, unless it fits one of those two definitions. Looking back at the definition of a branch circuit, I see that it uses the term "overcurrent protection device" in the singular.

Conclusion: If you have more than one OCPD, and if it is not a MWBC, then it violates 210.

Charlie,
I don't see it there. I don't see anything in the definition of a branch circuit that says all of the wires must be exclusive to that circuit. I don't see a provision that says a branch circuit can't share a grounded conductor with other branch circuits. In my example there are 3 branch circuits that share a single grounded conductor. It is not a MWBC because it does not meet the definition of one.

 

[charlie b]

Sorry, Don, I wasn?t clear.

I don't see anything in the definition of a branch circuit that says all of the wires must be exclusive to that circuit.

Not what I said (or tried to say). The definition of branch circuit requires the use of one, and only one, overcurrent device. If you have more than one OCPD, you do not have ONE branch circuit.

I don't see a provision that says a branch circuit can't share a grounded conductor with other branch circuits.

The definition of branch circuit speaks only about the ungrounded. We learn about the ability to share the grounded, when we learn about MWBCs, in 210.4. Since the code goes through the trouble of saying it is OK in this case, we have to conclude that if we don?t do it that way, it is not allowed. I think this is the point with which you will probably disagree.

In my example there are 3 branch circuits that share a single grounded conductor. It is not a MWBC because it does not meet the definition of one.

I agree that it is not a MWBC. Here is where that takes me:
(1) It is not ?a branch circuit,? and
(2) It is not a MWBC either, so therefore
(3) It is not covered by 210, and thus,
(4) It is not allowed.

Let me offer the following thought:
? A revision in the 2008 NEC requires handle ties, if I use an ungrounded from Phase A and an ungrounded from Phase B, and if I share the neutral.
? We must presume that they put that in because there would be a hazard, if there were no handle tie, and a person wanted to work on one circuit, without first opening both breakers.
? If I use two breakers and two ungrounded conductors from the same phase, and if I share the neutral, that same hazard (whatever it is) would exist here as well.
? That makes me happy that it is not allowed.

 

[roger]

? That makes me happy that it is not allowed.

But it is allowed in 225.7

Roger

 

[charlie b]

But it is allowed in 225.7

Thanks, Roger, that helped a bit.

I see you got that figure from the handbook. I see that the handbook has a similar figure for a three-phase panel. But I also see that the handbook's description of the two figures describes this situation as a multi-wire branch circuit, which it is not. So my level of confusion has not diminished. :-? :-?

 

[don_resqcapt19]

...
The definition of branch circuit speaks only about the ungrounded. We learn about the ability to share the grounded, when we learn about MWBCs, in 210.4. Since the code goes through the trouble of saying it is OK in this case, we have to conclude that if we don?t do it that way, it is not allowed. I think this is the point with which you will probably disagree.

Yes, it is my opinion that the code is a permissive code and that which is not specifically prohibited is permitted.

I agree that it is not a MWBC. Here is where that takes me:

(1) It is not ?a branch circuit,? and

It is not a single branch circuit....it is multiple branch circuits.

(2) It is not a MWBC either, so therefore

(3) It is not covered by 210, and thus,
(4) It is not allowed.

It is not specifically prohibited, so therefore it is permitted,

Let me offer the following thought:

? A revision in the 2008 NEC requires handle ties, if I use an ungrounded from Phase A and an ungrounded from Phase B, and if I share the neutral.
? We must presume that they put that in because there would be a hazard, if there were no handle tie, and a person wanted to work on one circuit, without first opening both breakers.
? If I use two breakers and two ungrounded conductors from the same phase, and if I share the neutral, that same hazard (whatever it is) would exist here as well.
? That makes me happy that it is not allowed.

Yes there is a hazard, but just because the code did not address that hazard, does not mean that the code prohibits this circuit. It is the CMPs position, a position that I do not agree with, that the two specific permissions to use this type of circuit act to prohibit all other uses of this type of circuit.
This all should be a moot issue when the 2011 is issued as there is an accepted proposal for Article 200 to prohibit this type of circuit except where specifically permitted elsewhere in the code.