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  1. #1
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    Get the code book.

    I had a report that a contractor received a red tag for improper whip to CU. THHN conductor inside NM liquid tite not OK. Must have UF cable inside NM liquid tite conduit. Apparently, in the new mechanical code,

    Anybody know of this code?

  2. #2
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    Wire rated for underground? Maybe because it has a ground wire embedded.

    Maybe that red tag was because the contractor did not pull a ground.
    If you were a real tech, you'd solder a relay on that board and call it good to go.

    I do a triple evac with nitro to remove non condensables.

    I use 56% silver on everything except steel.

    Did you really need the " If you were a real tech " ??

  3. #3
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    Was the wire dual rated THHN and THWN? I am not aware of that code, but it sounds like an inspector that does not know his job.
    Why is the mechanical inspector checking that? That is under the NEC code.

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  4. #4
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    What code? National Electric Code Year?, International Mech. Code Year? etc. Give us some info. Maybe a Texas amendment to a code. Never heard of that requirement. Nothing in the IMC-2012 Edition on power to a condenser at all. Sounds like BS to me. What code books and edition is Texas using? Give a little info. Thank you very much
    "I could have ended the war in a month. I could have made North Vietnam look like a mud puddle."

    "I have little interest in streamlining government or in making it more efficient, for I mean to reduce its size. I do not undertake to promote welfare, for I propose to extend freedom. My aim is not to pass laws, but to repeal them. It is not to inaugurate new programs, but to cancel old ones that do violence to the Constitution."
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  5. #5
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    The electrical part of mechanical codes is derived from the national electrical code.

    It sounds to me as though the inspector did not observe the fact that most THHN wire today is coded for multiple uses, as in THHN, THHN-2, THWN, etc.... which means that it is suitable for outdoor use, and seal tight is a correct choice for that. In addition, the seal tight is permissible for use as a ground in the code up to a certain current based upon the diameter of the seal tight becaise of the spiral metal used inside. Not all liquid tite raceway is listed for that use, so you have to know the product listing.

    Now.... it is possible that there was something about that installation which does not meet the local code, and the local code can be as restrictive as they want to make it, as long as it has been adopted into law as an ordinance of that municipality.

    So you would have to look into this further to know whether or not the failure was justified or if it was not.
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  6. #6
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    I have to question the idea that the failure was for THHN, and that the inspector wanted UF cable instead.

    Some folks believe that NM - B uses THHN listed for outdoor use, and that is not the case. If the outer jacket says NM-B, it cannot be used anywhere outdoors...in wet or damp locations... NM-B is strictly an indoor use only cable, and the inspector may have said if you want to use an assembled cable for this application it must be UF..... and that would be correct.
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  7. #7
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    Thread Starter
    Quote Originally Posted by timebuilder View Post
    I have to question the idea that the failure was for THHN, and that the inspector wanted UF cable instead.

    Some folks believe that NM - B uses THHN listed for outdoor use, and that is not the case. If the outer jacket says NM-B, it cannot be used anywhere outdoors...in wet or damp locations... NM-B is strictly an indoor use only cable, and the inspector may have said if you want to use an assembled cable for this application it must be UF..... and that would be correct.
    So what would you use NM liquid tight (seal tite) for? Just a casing for UF or inside? Why not just forget the seal tite all together.
    I am aware that some percent of a filled conduit reduces its ampacity, but don't know if omly pertains to current carrying wires.

  8. #8
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    Quote Originally Posted by timebuilder View Post
    I have to question the idea that the failure was for THHN, and that the inspector wanted UF cable instead.

    Some folks believe that NM - B uses THHN listed for outdoor use, and that is not the case. If the outer jacket says NM-B, it cannot be used anywhere outdoors...in wet or damp locations... NM-B is strictly an indoor use only cable, and the inspector may have said if you want to use an assembled cable for this application it must be UF..... and that would be correct.
    Also UF because of the jacket is limited to an amperage rateting of 60 Centigrade , 140 F.
    This must be Plano thing as I do the classroom CE and no mention of a change such as this.

  9. #9
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    As I understand it you can not put romax or UF cable inside conduit because of the possibility it will get to hot from the extra jacket. If this is the case it would make no sense to put UF inside NM sealtite. No I have seen where guys will try to run sealtite metal or NM from the hole in the house into the disconnect or from disconnect into the hole in the cabinet of the equipment with no fitting on 1 end. Without that fitting it makes the inside of the conduit a wet location which would require UF or other suitable cable.

  10. #10
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    The only limitation on placing a cable assembly in a raceway is adherence to conduit fill requirements. The cable dimension at it's widest is used as a conductor diameter for use with the tables in the back of the NEC book.
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  11. #11
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    Quote Originally Posted by timjimbob View Post
    I had a report that a contractor received a red tag for improper whip to CU. THHN conductor inside NM liquid tite not OK. Must have UF cable inside NM liquid tite conduit. Apparently, in the new mechanical code,

    Anybody know of this code?
    Huh?

    Which Mechanical Code?

    The NEC, doesn't call for UF to be run in liquid -Tite for a CU.
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  12. #12
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    Quote Originally Posted by DavidDeBord View Post
    Huh?

    Which Mechanical Code?

    The NEC, doesn't call for UF to be run in liquid -Tite for a CU.
    First, we are not getting the full story. The OP got it second hand.

    Next, imagine the contractor saying, "I want to just put a cable in the sealtite. What will you accept?"

    The code guy says, "you can put UF in there if you want to install a cable."

    Bottom line....if the THHN was manufactured in the last 10 years, it is most likely coded for all THHN variants

    it IS possible that he bought a bunch of discount whips that are not mult- use coded, too.
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  13. #13
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    Everyone here knows that you can buy pre made whips that are UL rated. Yes they have THHN wire inside and not cable.

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