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When can you use nameplate FLA?

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    #16
    I guess I would say it this way:
    From a technical perspective, FLA and FLC are the same (motor current in amps at full load), but conventions have evolved where the context of use implies a different source of the data.

    ??!

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      #17
      From a grammar standpoint, it would also depend on the nature of a question as asked.

      Q: “What is the Full Load Current of that motor?
      A: “123 Amps

      Q: “What is the Full Load Amps of that motor?
      A: “123

      In the second version it would be redundant to respond “123 amps” because amps was already embedded in the question. But I can’t think of a way to word that question to where the proper response would be “123 Full Load Current
      __________________________________________________ ____________________________
      Many people are shocked when they discover I am not a good electrician...

      I'm in California, ergo I am still stuck on the 2014 NEC... We'll get around to the 2017 code in around 2021.

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        #18
        I should have given this reference originally:

        430.6 Ampacity and Motor Rating Determination.
        (A) General Motor Applications. For general motor applications, current ratings shall be determined based on (A)(1) and (A)(2).
        (1) Table Values. Other than for motors built for low speeds (less than 1200 RPM) or high torques, and for multispeed motors, the values given in Table 430.247, Table 430.248, Table 430.249, and Table 430.250 shall be used to determine the ampacity of conductors or ampere ratings of switches, branch-circuit short-circuit and ground-fault protection, instead of the actual current rating marked on the motor nameplate. Where a motor is marked in amperes, but not horsepower, the horsepower rating shall be assumed to be that corresponding to the value given in Table 430.247, Table 430.248, Table 430.249, and Table 430.250, interpolated if necessary. Motors built for low speeds (less than 1200 RPM) or high torques may have higher full-load currents, and multispeed motors will have full-load current varying with speed, in which case the nameplate current ratings shall be used.


        Exception No. 3: For a listed motor-operated appliance that is marked with both motor horsepower and full-load current, the motor full-load current marked on the nameplate of the appliance shall be used instead of the horsepower rating on the appliance nameplate to determine the ampacity or rating of the disconnecting means, the branch-circuit conductors, the controller, the branch-circuit short-circuit and ground-fault protection, and any separate overload protection.


        Question is what does exception 3 typically apply to?

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          #19
          Originally posted by cppoly View Post
          ...
          Question is what does exception 3 typically apply to?
          "Appliance" is defined in article 100;
          Appliance. Utilization equipment, generally other than industrial, that is normally built in standardized sizes or types and is installed or connected as a unit to perform one or more functions such as clothes washing, air-conditioning, food mixing, deep frying, and so forth.
          Then Section 422 is devoted to them and it is in 422 that they first state that "motor-driven" appliances must follow article 430 rules, then they go on to describe non-motor driven appliances, like the frying and resistance heating type. So exception 3 is just reiterating what was already brought up in 422.
          __________________________________________________ ____________________________
          Many people are shocked when they discover I am not a good electrician...

          I'm in California, ergo I am still stuck on the 2014 NEC... We'll get around to the 2017 code in around 2021.

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            #20
            I stand corrected on nonlinear loads.

            https://www.ecmag.com/section/codes-...n-remains-same

            There are rules and weasel worded informational notes for neutrals based on nonlinear loads but that’s it.

            However as VFDs are or should be continuous loads (three hours or more) even though output fluctuates in an elevator application it certainly qualifies for the 125% rule for continuous loads. Most VFDs are powered continuously because the precharge circuits are not designed for routine power up. Many times installers on retrofits put the VFD on the output of a starter only to find it burns up frequently. The VFD manufacturers warn about this but the correct installation removes the contactor and powers it directly off the fuse/breaker. The exception is units with built in input contactors,


            Sent from my iPhone using Tapatalk

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              #21
              Originally posted by retirede View Post
              FLA and FLC are the same thing. I find FLA more commonly used over here.
              That's probably because you guys use "amperage" to mean current.

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                #22
                Originally posted by cppoly View Post
                If a motor operated appliance lists FLA, you're allowed to use this current and you're not required to get the FLC from the NEC tables right?

                So by extension, when a motor or motor appliance only lists HP, then you must use the tables??
                If it is a "motor operated appliance" then you should be using art 422, though it may send you to art 430 for certain things.

                Standard sized motors that are listed in tables at end of 430 need to use those table values for motor circuit calculations, this partly so that should motor need replaced (with same HP rating) the conductors should already be sufficient size even though the replacement may have some difference in efficiency rating.

                If you have a non standard sized motor (not in the tables) I see no choice but to use the motor nameplate rating for motor circuit calculations.

                In all cases motor overload protection is based on nameplate ratings, and overload protection may need replaced or readjusted when replacing a motor.
                I live for today, I'm just a day behind.

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                  #23
                  Originally posted by cppoly View Post
                  ...

                  Exception No. 3: For a listed motor-operated appliance that is marked with both motor horsepower and full-load current, the motor full-load current marked on the nameplate of the appliance shall be used instead of the horsepower rating on the appliance nameplate to determine the ampacity or rating of the disconnecting means, the branch-circuit conductors, the controller, the branch-circuit short-circuit and ground-fault protection, and any separate overload protection.
                  Question is what does exception 3 typically apply to?
                  That exception was added to address appliances such a central vacuum power units, air compressors and others where they use some very creative horsepower ratings for marking purposes.
                  Don, Illinois
                  (All code citations are 2017 unless otherwise noted)

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                    #24
                    Originally posted by don_resqcapt19 View Post
                    That exception was added to address appliances such a central vacuum power units, air compressors and others where they use some very creative horsepower ratings for marking purposes.
                    Or IMO, any other situation where a rating that is not in table in NEC is encountered. Those usually are OEM type applications though.

                    I run into a lot of crop drying fan motors that are single phase rated 12, 12.5 15, 16 Hp.

                    Used to be most of them were air-over rated on axial fans where the motor is in the airstream, but in more recent years have run into several 16 HP that are driving centrifugal fans and the motor is not in the air stream.

                    Largest motor in the NEC table for single phase is 10HP.
                    I live for today, I'm just a day behind.

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                      #25
                      Originally posted by paulengr View Post
                      ...

                      However as VFDs are or should be continuous loads (three hours or more) even though output fluctuates in an elevator application it certainly qualifies for the 125% rule for continuous loads. Most VFDs are powered continuously because the precharge circuits are not designed for routine power up. Many times installers on retrofits put the VFD on the output of a starter only to find it burns up frequently. The VFD manufacturers warn about this but the correct installation removes the contactor and powers it directly off the fuse/breaker. The exception is units with built in input contactors,


                      Sent from my iPhone using Tapatalk
                      Art 100 definition:
                      Continuous Load.
                      A load where the maximum current is expected to continue for 3 hours or more.
                      Just because something is powered continuously doesn't mean it is drawing "continuous load" all the time it is powered.

                      Certain code sections do state we must treat the particular load that section is about as continuous loads regardless of what kind of cycling you may see in the field. But that is the general way the NEC works, anything with a higher section number can overrule a lower section number for the most part.

                      I don't know elevator section very well at all and did glance through it. I don't know if an elevator motor is intended to be treated as continuous load or not. I'd guess nature of load would be non continuous, but NEC may still state you need to treat this one as continuous load, especially if it is a motor that is nameplated as a continuous duty motor. If it has any kind of intermittent duty on the nameplate then that is generally what triggers the ability to use conductors and overcurrent protection based on intermittent duty allowances when it comes to motors in general.
                      I live for today, I'm just a day behind.

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