Announcement

Collapse
No announcement yet.

When can you use nameplate FLA?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    When can you use nameplate FLA?

    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??

    #2
    You use FLA for overload sizing. FLC for everything else under 430.

    But shat you are describing sounds more like a 440 application which uses totally different rules from normal motors. You use what’s on the name plate. Are you sure you are in the right section?


    Sent from my iPhone using Tapatalk

    Comment


      #3
      This may be helpful

      ) 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
      They say I shot a man named Gray and took his wife to Italy
      She inherited a million bucks and when she died it came to me
      I can't help it if I'm lucky

      Comment


        #4
        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??
        HP and nameplate FLA are two different things. FLA is input current. HP is output power. Tells you nothing about power factor or efficiency so you can't accurately determine FLA from that.

        Comment


          #5
          Example D8 Motor Circuit Conductors, Overload
          Protection, and Short-Circuit and Ground-Fault
          Protection uses 'nameplate FLC'

          Unfortunately ,many motors one places a probe on won't portray this value until placed under a full load.

          ~RJ~

          Comment


            #6
            Originally posted by paulengr View Post
            You use FLA for overload sizing. FLC for everything else under 430.

            But what you are describing sounds more like a 440 application which uses totally different rules from normal motors.
            Ignorant Brit strikes again. Two questions this time.

            What is the difference between FLA and FLC?
            Full load Amps and full load current?
            We'd usually use FLC as the abbreviation.

            Second question.
            By 440 application I assume you mean 440V ? Apart from that not being one of your standard voltages, in what way does it differ from what you consider to be a "normal" motor that requires totally different rules?

            Comment


              #7
              Thanks for replies. I guess what I'm unsure about is when you can just look at the motor/motor appliance data sheet and use the FLA listed here and NOT be required to go to the NEC tables.

              For example,

              - If I have a motor operated appliance such as a blender, I would use the FLA listed on the appliance to determine the conductors and OCPD, right?

              - What if I have a sump pump and control panel and the data sheet only lists Full Load Amps but doesn't give the horsepower. I would also use the full load amps right and not NEC tables?

              Sometimes data sheets just don't give you HP so then you can use the FLA??

              Comment


                #8
                Originally posted by Besoeker3 View Post
                Ignorant Brit strikes again. Two questions this time.

                What is the difference between FLA and FLC?
                Full load Amps and full load current?
                We'd usually use FLC as the abbreviation.

                Second question.
                By 440 application I assume you mean 440V ? Apart from that not being one of your standard voltages, in what way does it differ from what you consider to be a "normal" motor that requires totally different rules?
                FLA and FLC are the same thing. I find FLA more commonly used over here.

                “440” application refers to NEC article 440 - Air conditioning and refrigeration equipment.

                Comment


                  #9
                  Originally posted by retirede View Post
                  FLA and FLC are the same thing. I find FLA more commonly used over here.

                  “440” application refers to NEC article 440 - Air conditioning and refrigeration equipment.
                  Information appreciated. Thank you.

                  Comment


                    #10
                    Originally posted by retirede View Post
                    FLA and FLC are the same thing. I find FLA more commonly used over here. ...
                    No. That is incorrect. Commonly done, but commonly incorrect.

                    FLA is the marking on the motor nameplate by the motor manufacturer for the motor's Full Load Amps.

                    FLC (Full Load Current) is a current value from a table in the NEC (430.247 through 250 depending on source) that is assigned to each HP rating. You are REQUIRED by code to use the FLC values from the table, NOT the FLA from the motor, for sizing conductors, switching devices and short circuit protective devices. The reason is that someone may someday change the motor and it may have a different FLA on the nameplate, but if you sized everything via the chart, the numbers they used are conservative enough to make it (relatively) safe to do so.

                    The ONLY thing that you use FLA for is in selecting running Over Load protection, a.k.a. heaters or settings on adjustable OL relays, VFDs, soft starters etc..
                    __________________________________________________ ____________________________
                    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.

                    Comment


                      #11
                      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??
                      The current is motor-specific, so overload protection needs to be sized for that.

                      The horsepower is application-specific, so replacements must be accommodated.
                      Master Electrician
                      Electrical Contractor
                      Richmond, VA

                      Comment


                        #12
                        Originally posted by Jraef View Post
                        No. That is incorrect. Commonly done, but commonly incorrect.

                        FLA is the marking on the motor nameplate by the motor manufacturer for the motor's Full Load Amps.

                        FLC (Full Load Current) is a current value from a table in the NEC (430.247 through 250 depending on source) that is assigned to each HP rating. You are REQUIRED by code to use the FLC values from the table, NOT the FLA from the motor, for sizing conductors, switching devices and short circuit protective devices. The reason is that someone may someday change the motor and it may have a different FLA on the nameplate, but if you sized everything via the chart, the numbers they used are conservative enough to make it (relatively) safe to do so.

                        The ONLY thing that you use FLA for is in selecting running Over Load protection, a.k.a. heaters or settings on adjustable OL relays, VFDs, soft starters etc..
                        There is nothing in the NEC that says that, in fact the language from 430.32 says:
                        ...motor nameplate full-load current rating ..
                        .
                        It has often been taught that way, but the code language never uses the term FLA. I teach nameplate current and Table or NEC current when I teach motors.
                        Don, Illinois
                        (All code citations are 2017 unless otherwise noted)

                        Comment


                          #13
                          Now i'm confused....~RJ~

                          Comment


                            #14
                            [QUOTE=don_resqcapt19;2012521]There is nothing in the NEC that says that, in fact the language from 430.32 says:
                            ...motor nameplate full-load current rating ..
                            OK, I see what you mean. You're right, it never says FLA vs FLC. It is explicit as to the difference between using the nameplate and using the charts, but it doesn't actually say FLA (or the words) anywhere. I stand corrected, I guess that was something I was taught in order to help avoid that confusion.

                            But maybe this is why... since you will never see the term FLA anywhere OTHER than on the motor nameplate, that's a good way to keep it straight. In fact NEMA MG 1 gives a definition of FLA as meaning "Full Load Amperes", and requires that "Amps" be shown on the nameplate, but it does NOT provide a definition of "FLC" nor use the word "current" in the nameplate requirements.

                            Semantics though.
                            Last edited by Jraef; 08-07-19, 07:49 PM.
                            __________________________________________________ ____________________________
                            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.

                            Comment


                              #15
                              [QUOTE=Jraef;2012531]
                              Originally posted by don_resqcapt19 View Post
                              There is nothing in the NEC that says that, in fact the language from 430.32 says:


                              OK, I see what you mean. You're right, it never says FLA vs FLC. It is explicit as to the difference between using the nameplate and using the charts, but it doesn't actually say FLA (or the words) anywhere. I stand corrected, I guess that was something I was taught in order to help avoid that confusion.
                              That’s what I was taught. And yes 440 is for HVAC which includes compressors and equipment that includes motors where the sizing rules are a bit different. I might have to actually visit Europe some day to be called an ignorant Brit. Guess dumb southern redneck will have to do. I learned 440 in the Code not on the wall socket. Under that section there is no table...you use name plate.

                              I’m going to look closer though because at least on the exam for 9 states they use FLC and FLA as you describe them. I know there are some trick answers where using name plate gives you the wrong answer. JC Rodriguez writes the tests for 8 states and he doex it that way. He doesn’t write NC exams but they do it that way.

                              And I agree with your logic especially because I work for a motor shop. FLA changes a little even when we rewind.

                              Not 100% sure but I think the table values are based on converting HP to kw then applying a 0.85 power factor and using the ANSI standard utilization voltage so for instance 460 then calculating amos. That should be pretty close to worst case on just about any motor except maybe some strange ones like NEMA curve D.


                              Sent from my iPhone using Tapatalk

                              Comment

                              Working...
                              X