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What Wire Size Is Required?

Discussion in 'Electrical Codes' started by jar546, Nov 22, 2018.

  1. jar546

    jar546 *****istrator

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    If you were to inspect this AC unit in an industrial warehouse that is fed by a 120/240 Delta with a 208 High Leg, and this was a single phase 240 fed by a double pole breaker, what wire size would you expect to see for this interior installation if the circuit was piped in with EMT to FMC?

    Would you check the position of the breaker in the panel or is it not relevant?

    IMG_1822.JPG
     
  2. RJJ

    RJJ Platinum Member

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    Is this unit on a roof top or ground set up? Is there a temp adjustment needed? What size conduit?
     
  3. jar546

    jar546 *****istrator

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    RJJ

     
  4. RJJ

    RJJ Platinum Member

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    I would check! AT Least an 8
     
  5. north star

    north star Sawhorse

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    @ ~ @

    RJJ,

    Why check the position the breaker, and what Article \
    Table would specify the AWG # 8 ?.....Also, what
    edition of the NEC is applicable ?

    Thanks !


    @ ~ @
     
  6. jar546

    jar546 *****istrator

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    #8 THHN is only good for 50A. This is not a 208 Wye
     
  7. ICE

    ICE Sawhorse

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    Prudence calls for qualifying the statement. #8 THHN is only good for 50A if all terminals etc. are rated at 75°.... it is not a # used for deration purposes.

    The equipment in your exercise was manufactured in 2002 and Shirley, the rest of the installation is an open question.
     
  8. jar546

    jar546 *****istrator

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    The Minimum Circuit Ampacity for this HVAC unit is 55A, therefore a #6 wire is required. Since there were only 2 current carrying conductors in the conduit and this is an interior installation, no derating was required.
     
  9. RJJ

    RJJ Platinum Member

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    Without seeing the breaker off the top of my head was the # 8. There are many factors to be considered. How far away is the breaker and under which code. Wire size to my knowledge has not changed over the last three code cycles.
     

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