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Feeders Vs Branch Circuits

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    Feeders Vs Branch Circuits

    Greetings to any knowledgeable engineer,
    Given the following layout, which are examples of feeders and which are examples of branch circuits? I assumed they were all feeders, but I was uncertain as to whether the conductors between HVAC equipment and a panel would be considered a feeder or a branch circuit. I am assuming most conductors that serve motor loads are considered feeders, but just wanted to verify? Also, is there a cutoff to where motor load equipment conductors are considered feeders and branch circuits? Please help.


    #2
    Even though your attachment isn't showing I know the answer to your question but since I'm not an engineer I will refrain from answering.

    Roger
    Moderator

    Comment


      #3
      Originally posted by roger View Post
      Even though your attachment isn't showing I know the answer to your question but since I'm not an engineer I will refrain from answering.

      Roger
      Per the NEC,

      Branch Circuit. The circuit conductors between the final overcurrent device protecting the circuit and the outlet(s). (CMP-2)

      Feeder. All circuit conductors between the service equipment, the source of a separately derived system, or other power supply source and the final branch-circuit overcurrent device. (CMP-2)

      If the panel contains the last overcurrent protection device before the HVAC eqiupment, by definition, the conductors between the panel and the HVAC equipment would be branch circuit conductors.

      Comment


        #4
        Originally posted by jtinge View Post

        Per the NEC,

        Branch Circuit. The circuit conductors between the final overcurrent device protecting the circuit and the outlet(s). (CMP-2)

        Feeder. All circuit conductors between the service equipment, the source of a separately derived system, or other power supply source and the final branch-circuit overcurrent device. (CMP-2)

        If the panel contains the last overcurrent protection device before the HVAC eqiupment, by definition, the conductors between the panel and the HVAC equipment would be branch circuit conductors.
        Well you are an engineer but are you a "knowledgeable engineer"

        Roger
        Moderator

        Comment


          #5
          Originally posted by roger View Post
          . . . but are you a "knowledgeable engineer"?
          Isn't that a contradiction in terms?

          FWIW, I agree with jtinge.

          Charles E. Beck, P.E., Seattle
          Comments based on 2017 NEC unless otherwise noted.

          Comment


            #6
            Originally posted by theophilus88 View Post
            I am assuming most conductors that serve motor loads are considered feeders, but just wanted to verify?
            Actually, the opposite is true.

            Originally posted by theophilus88 View Post
            Also, is there a cutoff to where motor load equipment conductors are considered feeders and branch circuits?
            Yes, and jtinge named it. It's the final overcurrent device before you get to the load. But I will put it another way. Consider the complete path of power flow from,
            1 The overhead lines along the nearby street,

            2 To the line that drops down the pole and goes underground to the service transformer,
            3 To the line that runs from the transformer secondary into the building's main service panel,
            4 Through one breaker on that main panel to a distribution panel,
            5 From one breaker on that panel to a branch circuit panelboard, and finally,
            6 From one breaker on that panel to the motor.

            Lines 1 and 2 belong to the utility company, and are not addressed in the NEC.
            Line 3 is called the "service conductors."
            Lines 4 and 5 are called "feeders."
            Line 6 is called a "branch circuit."
            Charles E. Beck, P.E., Seattle
            Comments based on 2017 NEC unless otherwise noted.

            Comment


              #7
              Originally posted by theophilus88 View Post
              I am assuming most conductors that serve motor loads are considered feeders, but just wanted to verify?
              Part of your confusion may be caused by some common slang.

              Most people refer to the conductors serving a motor as a "motor feeder". But going by the NEC definitions, they are usually "motor branch circuit conductors" and not feeders at all.



              Comment


                #8
                Originally posted by steve66 View Post



                Most people refer to the conductors serving a motor as a "motor feeder". But going by the NEC definitions, they are usually "motor branch circuit conductors" and not feeders at all.


                If the motor disconnect has OCP, then it's a feeder and if the motor disconnect does not have OCP it's a branch circuit?

                Comment


                  #9
                  If the OCPD at the motor is supplementary overcurrent protection it would still be a branch circuit from the OCPD to the supplementary OCP device.

                  240.10 Supplementary Overcurrent Protection. Where
                  supplementary overcurrent protection is used for luminaires,
                  appliances, and other equipment or for internal circuits and
                  components of equipment, it shall not be used as a substitute
                  for required branch-circuit overcurrent devices or in place of
                  the required branch-circuit protection. Supplementary over‐
                  current devices shall not be required to be readily accessible.
                  Rob

                  Moderator

                  All responses based on the 2017 NEC unless otherwise noted

                  Comment


                    #10
                    Originally posted by infinity View Post
                    If the OCPD at the motor is supplementary overcurrent protection it would still be a branch circuit from the OCPD to the supplementary OCP device.
                    Thank you (I should have known that).

                    Comment


                      #11
                      Thank you gentlemen for your additional clarifying comments to my original response. The reason I leverage so heavily on this forum.

                      Comment


                        #12
                        Originally posted by theophilus88 View Post
                        Greetings to any knowledgeable engineer,
                        Given the following layout, which are examples of feeders and which are examples of branch circuits?
                        Feeders are the aggregate circuit that serves a distribution device (panelboard, load center) containing multiple branch circuits. Feeders connect subpanels from the main panel, or the main panel from the service equipment.

                        Branch circuits connect the branch overcurrent device (e.g. branch breaker) to each load. Or to a daisy-chained group of loads, as is the case with receptacle and lighting circuits. The way to tell that it is a branch circuit, is that it will not have multiple paralleled overcurrent devices on the load side of the circuit.

                        In both cases, you can de-energize the feeders and branch circuits with customer-owned disconnects. Service conductors come ahead of feeders, ahead of the main service disconnect, with the essential difference being that you need the utility to shut down your service, to de-energize them.

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                          #13
                          Thank you everyone for your responses! These are definitely helpful. One thing that still bugs me is in regards to feeder/ circuits that serve a motor. Lets say you have a motor load being served from a main distribution panel. The conductors serving this equipment would be considered feeders would they not? Now let's say you have this same motor load being served from a branch panel (assuming our load is under 100A). Would the conductors serving the motor load from our branch panel be considered a branch circuit even though they are the same motor load? Let me know your thoughts.

                          Comment


                            #14
                            I don't see there being a difference which panel it came from.

                            Comment


                              #15
                              Originally posted by theophilus88 View Post
                              Thank you everyone for your responses! These are definitely helpful. One thing that still bugs me is in regards to feeder/ circuits that serve a motor. Lets say you have a motor load being served from a main distribution panel. The conductors serving this equipment would be considered feeders would they not? Now let's say you have this same motor load being served from a branch panel (assuming our load is under 100A). Would the conductors serving the motor load from our branch panel be considered a branch circuit even though they are the same motor load? Let me know your thoughts.
                              Isn't that a distinction without a difference? Would it make a difference to your wiring method if you called it one as opposed to the other?

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