Grounded neutral in an old sub-panel

Well, yeah, me too -- a bit. At least he recognizes that he has some things to learn, and is trying to learn them. I'll take that over an "already know everything" attitude _any_ day.
Reply to
Doug Miller
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Perhaps you could attach conduit to the underside of the beams?
That'll work.
Right.
Derating applies with more than three current-carrying conductors, which INcludes the neutral but EXcludes the ground.
Yes.
Waaaaaaaay too much work IMO.
Reply to
Doug Miller
|>|>| |>| Since the neutral conductor is uninsulated, it is in contact with the |>| sub-panel (it is in the conduit bringing the feed conductors into the |>| sub-panel). In a sub-panel the neutral and ground are not supposed to be |>| connected. |> |>That neutral conductor is, in today's terms, a grounding conductor (so it |>seems from your description). | | Incorrect. It is carrying return current and is therefore an uninsulated | neutral. He does not have a separate equipment grounding conductor.
You misunderstand what I am saying. I'll stand by my statement, but clarify it further for you: As a grounding conductor it is being misused by allowing it to carry current. If he adds an insulated conductor (marked white) and rewires the panel so the neutral current goes over the new conductor (which must be wired along side the phase conductors, of course), then the grounding conductor he already has can be used "as" a grounding conductor (as long as there are no other gotchas in his system that might otherwise disqualify it).
|>Another alternative: install a 240 to 120/240 volt transformer and derive a |>new neutral at the subpanel. That new neutral would be bonded to the ground |>at the transformer itself. | | That's also a Code violation. Neutral is required to be bonded to ground at | the service entrance, and is prohibited from being connected to ground at any | other point.
Wrong. The transformer creates a new derived system. The neutral of that new system BEGINS at the secondary of the transformer. It would be bonded to the ground at that point and that is how a it is done.
Reply to
phil-news-nospam
| It sounds like you have a subpanel feeding only 240V loads, with no | neutrals and what you have is no _neutral_ bus. The bare conductor being | a ground. Either that, or this is not in compliance with current code.
It sure sounded like a 240V only sub to me. But I bet it got used for 120V loads (out of compliance and likely dangerously). That's one reason I offered the transformer suggestion (isolation only, an autotransformer would not meet code there as it could still have ground currents).
Reply to
phil-news-nospam
| |>|>>Since the neutral conductor is uninsulated, it is in contact with the |> |>No, that is not an neutral conductor. It is a ground conductor. | | Actually, it *is* an uninsulated neutral (because it's carrying return | current). He has no ground.
It is physically wired LIKE a grounding wire. It is apparently used LIKE a neutral wire. It is wrong no matter which way you look at it.
But if you think of what is there now AS a grounding conductor, and if a new insulated current carrying conductor can be added to the existing conductors correctly (I don't know if that is the case), then that new one can be marked (white taped) as neutral and used that way, using the old uninsulated conductor as ground instead (if it is physically wired right for grounding).
Consider an old electric dryer circuit wired with 2 insulated conductors and one uninsulated conductor, terminating at a NEMA 10-30R outlet. You could replace the 10-30R with a 6-30R and make it legal (if the origin is a subpanel, be sure that ground wire is on the separate grounding bus). Of course the big problem is very few things work on 240 volt 30 amps. Maybe an arc welder. I wish they would make all dryers 240-volt-only in the future (they'd still work on a 14-30R circuit and be safer on the old 10-30R circuits).
Reply to
phil-news-nospam
I don't disagree -- but the fact that it *is* carrying current makes it a neutral.
Correct.
Incorrect. Bonding the neutral of the transformer secondary to the grounding conductor on the primary side is a Code violation.
Reply to
Doug Miller
Code violation. The grounded (neutral) conductor is required to have *continuous* white or gray insulation. White wires are permitted to be marked black, red, blue, etc. to identify them as ungrounded (hot), but not the reverse.
Reply to
Doug Miller
Sorry, my fault. Not a violation in this case. That requirement applies only to conductors 6AWG and smaller, and we're talking about at least 3AWG here.
Reply to
Doug Miller
A true neutral - that carries only the unbalanced current of the 2 phase conductors in this case - does not count. If there is a 60A load in any combination between A-B, A-N, B-N there will only be 60A 'going' and 60A 'returning'.
Reply to
bud--
| |>|>>But if you think of what is there now AS a grounding conductor, and if a |>>new insulated current carrying conductor can be added to the existing |>>conductors correctly (I don't know if that is the case), then that new |>>one can be marked (white taped) as neutral |> |>Code violation. The grounded (neutral) conductor is required to have |>*continuous* white or gray insulation. White wires are permitted to be marked |>black, red, blue, etc. to identify them as ungrounded (hot), but not the |>reverse. | | Sorry, my fault. Not a violation in this case. That requirement applies only | to conductors 6AWG and smaller, and we're talking about at least 3AWG here.
I believe it is "smaller than 6AWG" (e.g. 8AWG or smaller) based on the availability of insulation colors in a variety of sizes.
BTW, this is a rule that I would like to see another exception made for:
Using a cable assembly with conductors colored white,black,red,blue and in a dwelling building supplied only with single phase, the blue conductor may be marked white and used as a separate neutral paired to the red conductor.
Reply to
phil-news-nospam
| | | | Doug Miller wrote: |> |>Doug Miller wrote: |> |>>Code violation. The grounded (neutral) conductor is required to have |>>*continuous* white or gray insulation. White wires are permitted to be |>>marked black, red, blue, etc. to identify them as ungrounded (hot), |>>but not the reverse. |> |>Sorry, my fault. Not a violation in this case. That requirement applies only |>to conductors 6AWG and smaller, and we're talking about at least 3AWG here. | | (Mental picture of someone painting overhead high tension lines... )
Those are governed by a separate code: the NESC
Reply to
phil-news-nospam
"An insulated grounded conductor of 6AWG or smaller shall be identified by a continuous white or gray outer finish..." [2005 NEC, Article 200.6(A)]
Reply to
Doug Miller
|>|>|>|>|>| |>|>| Since the neutral conductor is uninsulated, it is in contact with the |>|>| sub-panel (it is in the conduit bringing the feed conductors into the |>|>| sub-panel). In a sub-panel the neutral and ground are not supposed to be |>|>| connected. |>|> |>|>That neutral conductor is, in today's terms, a grounding conductor (so it |>|>seems from your description). |>| |>| Incorrect. It is carrying return current and is therefore an uninsulated |>| neutral. He does not have a separate equipment grounding conductor. |> |>You misunderstand what I am saying. I'll stand by my statement, but clarify |>it further for you: As a grounding conductor it is being misused by allowing |>it to carry current. | | I don't disagree -- but the fact that it *is* carrying current makes it a | neutral.
It makes it used _as_ a neutral. Turn off the power and disconnect it from source and loads, and look only at the feeder and you won't know that it was used as a neutral. It could be the grounding conductor of a 2 wire 240 volt circuit.
My point is by looking at it that way, it may be repurposed (used) as the real grounding conductor (if it fully qualifies in all aspects of how it is installed) and a neutral would be added. Then you only need to add one conductor instead of two.
|> If he adds an insulated conductor (marked white) and |>rewires the panel so the neutral current goes over the new conductor (which |>must be wired along side the phase conductors, of course), then the grounding |>conductor he already has can be used "as" a grounding conductor (as long as |>there are no other gotchas in his system that might otherwise disqualify it). | | Correct. |> |> |>|>Another alternative: install a 240 to 120/240 volt transformer and derive a |>|>new neutral at the subpanel. That new neutral would be bonded to the ground |>|>at the transformer itself. |>| |>| That's also a Code violation. Neutral is required to be bonded to ground at |>| the service entrance, and is prohibited from being connected to ground at any |>| other point. |> |>Wrong. The transformer creates a new derived system. The neutral of that |>new system BEGINS at the secondary of the transformer. It would be bonded |>to the ground at that point and that is how a it is done. |> | Incorrect. Bonding the neutral of the transformer secondary to the grounding | conductor on the primary side is a Code violation.
Please cite code! (I think you will not find any such code unless it has been misinterpreted or misapplied)
Where would YOU bond it? To a separate grounding system not connected to the upstream? The grounding all has to be interconnected. Each neutral must be bonded to ground either at the entrance if it is part of a system entering the building, or at the system origin (the transformer itself or in certain cases the one panel being immediately fed by the transformer).
Think of a building that has 480Y/277 coming in and uses transformers to get either 208Y/120 (or 3 sets of 240/120 via three transformers). This is quite common. How do YOU think it is grounded?
Reply to
phil-news-nospam
|>| |>| Sorry, my fault. Not a violation in this case. That requirement applies only |>| to conductors 6AWG and smaller, and we're talking about at least 3AWG here. |> |>I believe it is "smaller than 6AWG" (e.g. 8AWG or smaller) based on the |>availability of insulation colors in a variety of sizes. | | "An insulated grounded conductor of 6AWG or smaller shall be identified by a | continuous white or gray outer finish..." [2005 NEC, Article 200.6(A)]
Great! You looked it up faster than I did. But now we know you have a copy of the code and know how to read it. So after you review 310.15(B)(4) regarding the exemption of the neutral from being counted in the multiple conductor adjustment factor, you can take a look at 250.30(A)(1) exception number 2 before hunting for that code you think prohibits bonding of the neutral of a separately derived system to the grounding electrode of the feed to the transformer primary side.
Reply to
phil-news-nospam
Of course; but I don't recall anybody suggesting that the OP needed to add two conductors.
Hmmmm. I think you're right. Thanks for educating me.
Reply to
Doug Miller

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