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    single phase 208v neutral

    IN a single phase 208v application in most cases no neutral is needed, is there no return path. No one has explained this to me properly. Also is what is refered to as a "common" wire another term for neutral.

    #2
    If you start with a three phase, 120/208 volt system, and if you connect a load between two phases, you will get 208 volts to the load, and the neutral wire will not be part of the circuit. Any current that flows from the source via one ungrounded conductor, and passes through the load, will return to the source via the other ungrounded conductor.





    Does that answer your question?
    Charles E. Beck, P.E., Seattle
    Comments based on 2017 NEC unless otherwise noted.

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      #3
      Originally posted by Matt B
      IN a single phase 208v application in most cases no neutral is needed, is there no return path. No one has explained this to me properly. Also is what is refered to as a "common" wire another term for neutral.
      Charlie is absolutely correct. I have heard of "common" being referred to as the neutral or grounded conductor. It is not good terminology because it can mean many things.
      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 Matt B
        IN a single phase 208v application in most cases no neutral is needed, is there no return path. No one has explained this to me properly. Also is what is refered to as a "common" wire another term for neutral.
        I wouldn't make that statement relating to 208 volts. I often do an apartment complex with a 120/208 volt 3 phase service and 120/208 volts single phase to each apartment. These have a neutral and provide 120 volts for lights, receptacles, etc. I can use 208 volts without a neutral, but I regularly have a 120/208 volt single phase system with 2 hot wires and a netural.
        I have heard the neutral referred to as a common, but agree with Charlie and Dennis that it is more often used for a dc system.

        Jim T

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          #5
          jtester:

          The term single phase with 208 is common terminology and I believe by definition meets the criteria.

          Three phase - 120/208 3-phase 4 wire wye
          Which allows:

          3-phase 3-wire 208 VAC
          Single phase 2-wire 208 VAC
          Single phase 2-wire 120 VAC


          In addition what you describe, 120/208 2 p hases/ 2 ungrounded conductors and a grounded conductor (3-phase 3 wire) is commonly referred to as single phase.

          Not positive if all these meet the definition of single phase, but the terminology is utilized, of course as noted in another post some lay people call the neutral/grounded conductor a common.

          Will research this when I get to my office.



          http://www.windstuffnow.com/main/3_phase_basics.htm
          Last edited by brian john; 02-15-07, 08:44 PM.
          Brian John
          Leesburg, VA

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            #6
            Brian

            In my post I was cautioning against thinking that 208 usually didn't need a neutral. I didn't mean that it couldn't be single phase. I'm sorry for the confusion.

            In this area, if someone tells me it is a 208 single phase system, I can't assume it doesn't have a neutral.

            Jim T

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              #7
              Single phase 2-wire 208 VAC SINGLE PHASE TWO WIRE CIRCUIT
              Single phase 2-wire 120 VAC SINGLE PHASE TWO WIRE CIRCUIT
              120/208 2 phases/ 2 ungrounded conductors and a grounded conductor (3-phase 3 wire) . SINGLE PHASE THREE-WIRE CIRCUIT


              All of these terms have a definition in the IEEE dictionary and a somewhat similar definition in the "dictionary For The electrician With formulas" by Tom Henry
              Brian John
              Leesburg, VA

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                #8
                Originally posted by brian john
                .....120/208 2 phases/ 2 ungrounded conductors and a grounded conductor (3-phase 3 wire) . SINGLE PHASE THREE-WIRE CIRCUIT


                All of these terms have a definition in the IEEE dictionary and a somewhat similar definition in the "dictionary For The electrician With formulas" by Tom Henry

                Why do you call that (3 phae 3 wire)?

                Jim T

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                  #9
                  Originally posted by jtester
                  Brian

                  In my post I was cautioning against thinking that 208 usually didn't need a neutral.

                  Jim T

                  I believe Charlie B was referring to Utilization equip. (i.e. motors, heaters....) not necessarily a feed to a sub panel. I believe it was well explained by him.
                  ____________________________

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                    #10
                    Originally posted by barbeer
                    I believe Charlie B was referring to Utilization equip. (i.e. motors, heaters....) not necessarily a feed to a sub panel. I believe it was well explained by him.
                    I agree.

                    Jim T

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                      #11
                      JimT typo....My Mother always told me to take typing. In the 60"s I never saw a need for it.
                      Brian John
                      Leesburg, VA

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                        #12

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