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Thread: A/C wiring

  1. #1
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    Default A/C wiring

    Wiring from 240 V A/C unit to breaker was three wire. White neutral wire had black tape around it and was being used as second hot wire to breaker. Copper ground wire was connected to neutral bar at panel. This dosen't seem correct but I remember reading somewhere that this was acceptable if wired to A/C unit with service disconnect (which was present). Sorry no picture. Any comments?

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  2. #2
    David Banks's Avatar
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    Default Re: A/C wiring

    Sounds all right to me except black tape is not a permanent marking.
    I do not have the code.


  3. #3
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    Default Re: A/C wiring

    "must be permanently re-identified by painting or other effective means" and tape is not permanent.

    Tape is allowed to mark black for white (not required to be permanent) but is not allowed to mark white for black (is required to be permanent).

    And, not just there, but at everyplace "where it is visible and accessible" too.

    Jerry Peck, Construction / Litigation Consultant
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    Default Re: A/C wiring

    Once again, there is the disagreement over using tape to mark a wire. My opinion: Not a problem. Especially when a cable is used .... it's not like you can pull a new wire.

    Beyond that, it's a debate over what "permanent" is, and for that we need to defer to the "authority having jurisdiction." Whoever that may be, it's not us.


  5. #5
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    Default Re: A/C wiring

    No debate over permanent, tape is allowed for use when re-identifying black/red, etc., colors to other colors - if the tape comes off, the color is still a 'hot' color, whereas when white is re-identified to black/red etc., when the tape comes off it leaves a 'neutral' color ("white") which is not allowed.

    The code specifically allows tape for the former and does not require it to be "permanent", the code specifically requires white to be "permanently" re-identified "by painting" or other effective means for the later.

    However, something we all failed to address the first time around was:

    "White neutral wire had black tape around it and was being used as second hot wire to breaker. Copper ground wire was connected to neutral bar at panel."

    Not allowed.

    The ground wire is being used as a neutral the other 120 volt circuit that the white has been taped up for use with.

    NOT ALLOWED.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
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    Default Re: A/C wiring

    Thanks Jerry, Thats the part that concerned me, it should have been 4 wire with red and black as hots, white to neutral bar and ground to ground bar. I guess 3 wire is cheaper or they didn't have any.

    Tom Rees / A Closer Look Home Inspection / Salt Lake City, Utah

  7. #7
    Brandon Chew's Avatar
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    Default Re: A/C wiring

    Quote Originally Posted by Jerry Peck View Post
    However, something we all failed to address the first time around was:

    "White neutral wire had black tape around it and was being used as second hot wire to breaker. Copper ground wire was connected to neutral bar at panel."

    Not allowed.

    The ground wire is being used as a neutral the other 120 volt circuit that the white has been taped up for use with.

    NOT ALLOWED.

    Jerry - if this was a 120V multiwire branch circuit I would agree with you. It's for a 240V A/C circuit. If the "copper ground wire was connected to neutral bar at panel", and that panel is the one with the service equipment, and if the ground bar, neutral bar, and enclosure are all bonded together at the service equipment like they are supposed to be, then I don't see a problem with having the ground wire connected to the neutral bar. Am I missing something?


  8. #8
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    Default Re: A/C wiring

    Quote Originally Posted by Brandon Chew View Post
    Jerry - if this was a 120V multiwire branch circuit I would agree with you. It's for a 240V A/C circuit. If the "copper ground wire was connected to neutral bar at panel", and that panel is the one with the service equipment, and if the ground bar, neutral bar, and enclosure are all bonded together at the service equipment like they are supposed to be, then I don't see a problem with having the ground wire connected to the neutral bar. Am I missing something?
    Brandon,

    From the original post: "Wiring from 240 V A/C unit to breaker was three wire. White neutral wire had black tape around it and was being used as second hot wire to breaker. Copper ground wire was connected to neutral bar at panel."

    The only reason to "White neutral wire had black tape around it and was being used as second hot wire to breaker" would be to use that as a separate circuit, which would need to have a neutral return.

    The "Copper ground wire was connected to neutral bar at panel." was connected to the neutral terminal bar for that neutral return - however, it is an uninsulated bare copper wire, which is not allowed for use as a neutral (which is what everyone calls that conductor, it is really a "grounded" conductor, and not a "neutral" conductor, however, that does not affect the fact that it is required to be insulated).

    The problems, then, are (and maybe I should have gone into more detail):

    - The 'neutral' for the 120 volt circuit is the bare ground wire, which is not allowed for that use.

    - The 'ground' (which it may also be being used for) is now being used to carry intended current, and 'equipment grounding conductors' are not 'intended to carry current'.

    - The 'neutral' may not be also being used for a 'ground' in which case there would not be a ground to the a/c unit.

    - The correction is simple (yeah, right) in that all which needs to be done is to disconnect the black-taped-white-wire from the breaker, killing power to whatever it was feeding, and re-connect (make sure it is connected) the bare copper ground wire to the ground at the a/c equipment and at the panel.

    - Then, of course, a new circuit would need to be run for whatever was being feed from that circuit (the 'yeah, right' part).

    - OR ... if the breaker protecting the conductors to the a/c unit, and the conductors themselves, are large enough, a 4-6-8 circuit panel could be installed at the a/c equipment end, with the white being connected to the neutral terminal bar, the two hots to the two hot terminals, and the equipment ground to the ground terminal, then feed the a/c off a double pole breaker and feed whatever else off another breaker. All depending on *IF* "the breaker protecting the conductors to the a/c unit, and the conductors themselves, are large enough" ...

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  9. #9
    Brandon Chew's Avatar
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    Default Re: A/C wiring

    Jerry, this part, I am aware of and fully agree:

    Quote Originally Posted by Jerry Peck View Post
    Brandon,

    From the original post: "Wiring from 240 V A/C unit to breaker was three wire. White neutral wire had black tape around it and was being used as second hot wire to breaker. Copper ground wire was connected to neutral bar at panel."

    [portion snipped and quoted below]

    The "Copper ground wire was connected to neutral bar at panel." was connected to the neutral terminal bar for that neutral return - however, it is an uninsulated bare copper wire, which is not allowed for use as a neutral (which is what everyone calls that conductor, it is really a "grounded" conductor, and not a "neutral" conductor, however, that does not affect the fact that it is required to be insulated).

    The problems, then, are (and maybe I should have gone into more detail):

    - The 'neutral' for the 120 volt circuit is the bare ground wire, which is not allowed for that use.

    - The 'ground' (which it may also be being used for) is now being used to carry intended current, and 'equipment grounding conductors' are not 'intended to carry current'.

    - The 'neutral' may not be also being used for a 'ground' in which case there would not be a ground to the a/c unit.

    - The correction is simple (yeah, right) in that all which needs to be done is to disconnect the black-taped-white-wire from the breaker, killing power to whatever it was feeding, and re-connect (make sure it is connected) the bare copper ground wire to the ground at the a/c equipment and at the panel.

    - Then, of course, a new circuit would need to be run for whatever was being feed from that circuit (the 'yeah, right' part).

    - OR ... if the breaker protecting the conductors to the a/c unit, and the conductors themselves, are large enough, a 4-6-8 circuit panel could be installed at the a/c equipment end, with the white being connected to the neutral terminal bar, the two hots to the two hot terminals, and the equipment ground to the ground terminal, then feed the a/c off a double pole breaker and feed whatever else off another breaker. All depending on *IF* "the breaker protecting the conductors to the a/c unit, and the conductors themselves, are large enough" ...
    Here is where we differ:

    Quote Originally Posted by Jerry Peck View Post
    The only reason to "White neutral wire had black tape around it and was being used as second hot wire to breaker" would be to use that as a separate circuit, which would need to have a neutral return.
    What is wrong with running a 10-2 w/ground NM cable (assuming proper conductor and breaker sizes) from the panel that contains the service equipment to the disconnect for the A/C unit, permanently re-identifying the white conductor at each end as an ungrounded conductor, and then inside the panel with the service equipment (where the grounded conductors, grounding conductors, and enclosure are bonded together as required), you make the following connections?:
    • black conductor to a breaker on one bus
    • original white, now permanently re-identified conductor, to a breaker on the other bus
    • bare copper grounding conductor to either the grounding or grounded conductor terminal bars
    You have a three wire circuit with two "hots" (ungrounded) supplying the 240V, no "neutral" (grounded), and a bare "ground" (grounding). This is a typical wiring method for 240V A/C circuits around here. The "problem" that I see with the original post is that the tape does not "permanenty re-identify" the white conductor.

    Last edited by Brandon Chew; 03-28-2008 at 09:28 AM. Reason: add last sentence to post.

  10. #10
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    Default Re: A/C wiring

    Quote Originally Posted by Brandon Chew View Post
    What is wrong with running a 10-2 w/ground NM cable (assuming proper conductor and breaker sizes) from the panel that contains the service equipment to the disconnect for the A/C unit, permanently re-identifying the white conductor at each end as an ungrounded conductor, and then inside the panel with the service equipment (where the grounded conductors, grounding conductors, and enclosure are bonded together as required), you make the following connections?:
    • black conductor to a breaker on one bus
    • original white, now permanently re-identified conductor, to a breaker on the other bus
    • bare copper grounding conductor to either the grounding or grounded conductor terminal bars
    You have a three wire circuit with two "hots" (ungrounded) supplying the 240V, no "neutral" (grounded), and a bare "ground" (grounding). This is a typical wiring method for 240V A/C circuits around here. The "problem" that I see with the original post is that the tape does not "permanently re-identify" the white conductor.
    Not sure if you missed this in the original post "Wiring from 240 V A/C unit to breaker was three wire." or if you are missing the fact that a (from your example) "2 w/ground NM cable" is a two-wire circuit, not a three wire circuit as stated.

    The original poster said "Wiring from 240 V A/C unit to breaker was three wire.", that means it had one black, one red, one white (i.e., three wires) and one ground.

    The way I am visualizing what was stated is: (three wire circuit)

    - black to breaker
    - red to breaker
    - white taped and to another breaker
    - ground to neutral and being used as the neutral for the 'hot' taped up white conductor connected to another breaker.

    Regarding your example: "2 w/ground NM cable", yes, you could: (two wire circuit)
    - black to breaker
    - permanently re-identify the white to red (or black) by painting, then red to breaker (and do that permanent re-identification at all accessible and visible locations)
    - ground to ground, which, at the service equipment, would also be the neutral bar

    I think the mis-communication is in the understanding of what two-wire and three-wire means. The equipment ground is not counted when making those determinations (the equipment ground could be a metal raceway and not a "wire").

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  11. #11
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    Default Re: A/C wiring

    Quote Originally Posted by Jerry Peck View Post
    Regarding your example: "2 w/ground NM cable", yes, you could: (two wire circuit)

    - black to breaker
    - permanently re-identify the white to red (or black) by painting, then red to breaker (and do that permanent re-identification at all accessible and visible locations)
    - ground to ground, which, at the service equipment, would also be the neutral bar

    I think the mis-communication is in the understanding of what two-wire and three-wire means. The equipment ground is not counted when making those determinations (the equipment ground could be a metal raceway and not a "wire").
    I think the question wasn't clear to begin with, but I think he was asking whether it was OK for the ground conductor to terminate at the neutral busbar. We obviously don't know if the neutrals and grounds are bonded together in the panel, so it's hard to answer that question.

    I think it is obvious that the reference is to a 2 wire + ground, although he's not using the correct terminology. There's no mention of a red conductor.

    What the service disconnect part of the question means, i don't know.


  12. #12
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    Default Re: A/C wiring

    Tom R., can you clarify where the wiring was beginning. Was it at the service panel or a downstream panel? I think if it is at the service panel, there isn't anything wrong with connecting the ground to the neutral bar, since they are one and the same (or should be) as the ground bar. White wire should be painted or permanently marked but I have yet to see it. I'm lucky if they bother to tape it.

    Jim Robinson
    New Mexico, USA

  13. #13
    Brandon Chew's Avatar
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    Default Re: A/C wiring

    Quote Originally Posted by Jerry Peck View Post
    I think the mis-communication is in the understanding of what two-wire and three-wire means. The equipment ground is not counted when making those determinations (the equipment ground could be a metal raceway and not a "wire").
    Therein lies the rub. When he said "Wiring from 240 V A/C unit to breaker was three wire" and then described the white as a "second hot", made no mention of a red, and then spoke of the ground, I was thinking that he was using slang to say the cable had three "wires" (two insulated conductors plus one bare one), and not that he was using the formal term "three-wire circuit". This thought was reinforced by Tom's reply to you with:
    Thanks Jerry, Thats the part that concerned me, it should have been 4 wire with red and black as hots, white to neutral bar and ground to ground bar. I guess 3 wire is cheaper or they didn't have any.:
    I made my own mistake when I incorrectly called my 10-2 w/ground example a three wire circuit. You're right, that's a two wire circuit ... I think I had three wire stuck in my brain...

    Now Tom - help us clear this up and give you some good consistent advice. How many conductors were running between the A/C unit and the panel, what colors were they and to what were they connected?


  14. #14
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    Default Re: A/C wiring

    Sorry about this whole mess up. Let me start over. I made the same mistake and called two wire three wire. This is how circuit was wired: there was a 10-2 w/ground NM running from A/C service disconnect breaker to electrical service panel. So there was a black wire, a white wire and a bare ground wire. The black wire and white wire (with black tape on it) were wired to 240 breaker as hots. Bare ground wire was connected to neutral bar at service panel. There was no neutral wire since there were only the white (with black tape), black and bare ground. The A/C service disconnect breaker was locked so I could not see inside it and had no way to get key at the time. I will be more careful to fully explain the situation next time.

    Tom Rees / A Closer Look Home Inspection / Salt Lake City, Utah

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    Default Re: A/C wiring

    Tom,

    Okie dokie - let's "start over".

    *IF*, as you stated in the first post, this is "service equipment" with the main disconnect, then ...

    ... the comments about the permanent re-identification from white still apply.

    Forget about the other comments about the ground being used as a return for another circuit.

    Easier?

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  16. #16
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    Default Re: A/C wiring

    Thanks Jerry.

    Tom Rees / A Closer Look Home Inspection / Salt Lake City, Utah

  17. #17
    Brandon Chew's Avatar
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    Default Re: A/C wiring

    Quote Originally Posted by Jerry Peck View Post
    Tom,

    Okie dokie - let's "start over".

    *IF*, as you stated in the first post, this is "service equipment" with the main disconnect, then ...

    ... the comments about the permanent re-identification from white still apply.

    Forget about the other comments about the ground being used as a return for another circuit.

    Easier?
    Agreed. If this is service equipment, the defect is that tape doesn't "permanently re-identify" (<--code term) the white. At the service equipment and only at the service equipment, it is OK to have the ungrounded conductors (white/neutrals) and the grounding conductors (bare/grounds) land on the same terminal bar. This is because at the service equipment the ungrounded conductors and the grounding conductors are required to be bonded to each other and everywhere else downstream they are required to be kept separate. If this is the service equipment and they are not bonded, that's another defect to call out.

    While we are on this subject, this would be a good time to remind some folks that every ungrounded conductor (white/neutral) is required to be alone, by itself, under a terminal screw. Not doubled up with another ungrounded conductor or with a grounded (bare/ground) conductor. The latter situation is found frequently ... it's wrong ... it's been wrong for many many years but the practice persists ... so in the latest version of the NEC they spell it out to make it clear to everyone.

    Thanks Tom & Jerry.

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