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Thread: Anyone have a link to insulation codes (XHHW, TW, RH, THHN etc)

  1. #11
    Join Date
    Feb 2008
    Location
    Indiana
    Posts
    266
    Quote Originally Posted by zbang
    I think you have to consider some letters as two-letter codes, for instance MT/MC/MI, since M could be either metal or machine. Also that a letter might have one meaning in the first position and others later in the code.

    S- I've always heard that as "Stage", it's not silicone.
    J- Junior (thinner insulation)
    O- Oil reisitant
    OO- Really oil resistant
    A- Asbestos
    I was thinking S was silicone as in SRML - Silicone Rubber Motor Lead

  2. #12
    Join Date
    Feb 2008
    Location
    Houston
    Posts
    663

    Building Wire and Cable Designations


  3. #13
    Join Date
    Feb 2008
    Location
    Indiana
    Posts
    266
    Quote Originally Posted by Chamuit
    That gets a lot of them. Thanks for the link. Here's a cut and paste from the link:

    Building Wire and Cable Designations


    by Technical Support


    Technical Information & Technical Bulletins



    THW-2: Thermoplastic Insulation (usually PVC), Heat Resistant (90C rating), suitable for Wet locations.



    THWN-2: Same as THW except Nylon jacket over reduced insulation thickness. Also rated THHN.



    THHN: Thermoplastic Insulation (usually PVC), High Heat Resistant (90C rating), dry locations only, Nylon jacket. Also rated THWN.



    TFFN: Thermoplastic Insulation (usually PVC), Flexible Fixture wire, Nylon jacket. Also rated MTW and AWM.



    TFN: Thermoplastic Insulation (usually PVC), Fixture wire, Nylon jacket. Also rated AWM.



    XHHW-2: Cross-linked Polyethylene Insulation (X) High Heat Resistant (90C rating) for Wet and dry locations.



    RHH: Rubber Insulation (we actually use cross-linked polyethylene because it qualifies for rubber), High Heat Resistant (90C rating) for dry locations only.



    RHW-2: Rubber Insulation (again, cross-linked polyethylene is used by most manufacturers), Heat Resistant (90C), Suitable for Wet locations.



    USE-2: Underground Service Entrance. Most utilize cross-linked polyethylene insulation rated for 90C in direct burial applications. Product is usually triple rated RHHRHW2-USE-2.



    MTW: Machine Tool Wire. Usually thermoplastic insulation (PVC) or thermoplastic insulation with nylon jacket. Most MTW is rated 60C. Southwire's copper type THHN is also rated MTW.



    AWM: Appliance Wiring Material. Usually thermoplastic insulation (PVC) or thermoplastic insulation with nylon jacket. Southwire's stranded copper type THHN in AWG sizes 14 through 6 is also rated AWM. As AWM, the product carries a 105C rating.



    NM-B: Nonmetallic-Sheathed Cable. The "B" denotes that individual conductor insulation is rated 90C; however, ampacity is limited to that for a 60C conductor (see NEC Section 336-26, 1999 edition). Thermoplastic (PVC) conductor insulation-nylon jacketed, with overall PVC cable jacket.



    UF-B: Undergound Feeder. The "B" denotes that individual conductor insulation is rated 90C; however, ampacity is limited to that for a 60C conductor (see NEC Section 339-3(a)(4), 1999 edition.) Thermoplastic (PVC) conductor insulation-nylon jacketed, with overall PVC cable jacket.



    SEU: Service Entrance Cable, Unarmored. Usually type XHHW insulated conductors with overall PVC jacket. As such, the cable is rated for 90C dry, 75C wet locations. Another school of thought is the "U" in the designation denotes the shape of the cable (if you look at the end, it resembles a closed "U" shape).



    SER: Service Entrance Cable, Round. Same construction material-wise as SEU, but round construction affords use of more than 3 conductors to which SEU is limited.

  4. #14
    Join Date
    Jun 2006
    Location
    Ohio
    Posts
    15,465
    Quote Originally Posted by C3PO
    I believe you can find that in the UL marking guides also.
    http://www.ul.com/regulators/W&CMG_April2007_Final.pdf

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