Page 1 of 3 123 LastLast
Results 1 to 10 of 141

Thread: Indoor unit

Hybrid View

Previous Post Previous Post   Next Post Next Post
  1. #1
    Join Date
    Jul 2017
    Location
    MD, USA
    Posts
    628

    Indoor unit

    I have gas furance indoor unit which uses 3/4 hp 120v fan for heating. No MOCP is provided. Is it because this is not hematric motor or compressor for heating? What would be properly size overcurrent protection be for that fan nec 2014?

    Sent from my SM-G935U using Tapatalk

  2. #2
    Join Date
    Jan 2009
    Location
    3 Hr 2 Min from Winged Horses
    Posts
    15,682
    A disconnecting means would be required. It probably would not contain an OCPD, unless fuses are speced.

    The OCPD for short circuit and ground fault protection would prolly be the panel breaker.

    OCPD type and multiplier for start up current would be chosen per 430.52 , motor ampacity would be chosen from motor tables at end of 430, not the nameplate.

    overload protection is probably built into the motor given the size. nameplate should say or have “TP” as part of motor identification.
    "Electricity is really just organized lightning." George Carlin


    Derek

  3. #3
    Join Date
    Jul 2017
    Location
    MD, USA
    Posts
    628
    Quote Originally Posted by jumper View Post
    A disconnecting means would be required. It probably would not contain an OCPD, unless fuses are speced.

    The OCPD for short circuit and ground fault protection would prolly be the panel breaker.

    OCPD type and multiplier for start up current would be chosen per 430.52 , motor ampacity would be chosen from motor tables at end of 430, not the nameplate.

    overload protection is probably built into the motor given the size. nameplate should say or have “TP” as part of motor identification.
    Does not tell me percent to us based on RLA or FLA. Also what about table 430.248 i cannot use that?

    Sent from my SM-G935U using Tapatalk

  4. #4
    Join Date
    Jul 2017
    Location
    MD, USA
    Posts
    628
    Quote Originally Posted by codequestion View Post
    Does not tell me percent to us based on RLA or FLA. Also what about table 430.248 i cannot use that?

    Sent from my SM-G935U using Tapatalk
    Would 20 amp be ok?

    Sent from my SM-G935U using Tapatalk

  5. #5
    Join Date
    Jul 2017
    Location
    MD, USA
    Posts
    628
    Quote Originally Posted by codequestion View Post
    Would 20 amp be ok?

    Sent from my SM-G935U using Tapatalk
    Ok i got it nevwr mind percents are right there on table. So what about size of non fused disconnect itself for the fans. 20 amps non fused disconnect ok for the fans?

    Sent from my SM-G935U using Tapatalk

  6. #6
    Join Date
    Jan 2009
    Location
    3 Hr 2 Min from Winged Horses
    Posts
    15,682
    Quote Originally Posted by codequestion View Post
    Ok i got it nevwr mind percents are right there on table. So what about size of non fused disconnect itself for the fans. 20 amps non fused disconnect ok for the fans?

    Sent from my SM-G935U using Tapatalk
    What code section would or would not allow this? Look for motor disconnecting means in 430.

    What does it tell you?

    We can discuss your answer after you present one.
    "Electricity is really just organized lightning." George Carlin


    Derek

  7. #7
    Join Date
    Jan 2009
    Location
    3 Hr 2 Min from Winged Horses
    Posts
    15,682
    Quote Originally Posted by codequestion View Post
    Does not tell me percent to us based on RLA or FLA. Also what about table 430.248 i cannot use that?

    Sent from my SM-G935U using Tapatalk
    Why do you think you cannot use 250.248? You have a single phase AC motor.
    "Electricity is really just organized lightning." George Carlin


    Derek

  8. #8
    Join Date
    Aug 2006
    Location
    Miami Fla.
    Posts
    7,473
    See T430.52. OL protection is a different story.

    Or what Derek said

  9. #9
    Join Date
    Jul 2017
    Location
    MD, USA
    Posts
    628
    Pub un

    Sent from my SM-G935U using Tapatalk

  10. #10
    Join Date
    Dec 2011
    Location
    Wisconsin
    Posts
    460
    Quote Originally Posted by codequestion View Post
    Pub un

    Sent from my SM-G935U using Tapatalk
    Not sure what this means.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •