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    Largest 120/208 volt service

    What is the largest 120/208 volt Y service you've ever encountered in your career?
    Our comedian shamelessly joked about a blackout. Talk about dark humor.

    #2
    Originally posted by mbrooke View Post
    What is the largest 120/208 volt Y service you've ever encountered in your career?
    Common here is 400/230V Y as nominal voltage LV distribution. Typically they are around 1.5MVA.

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      #3
      I recall being involved in a design that had a 120/208V, 5000 amp main board. It was for a mixed use high rise building. There was an interest in an even higher rating. But there was some issue with the utility company's limits on their metering equipment.
      Charles E. Beck, P.E., Seattle
      Comments based on 2017 NEC unless otherwise noted.

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        #4
        Originally posted by Besoeker3 View Post

        Common here is 400/230V Y as nominal voltage LV distribution. Typically they are around 1.5MVA.
        What is the perspective fault current on something like that?
        Our comedian shamelessly joked about a blackout. Talk about dark humor.

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          #5
          Our current project has 4-4000 amp services at 208Y/120 volts. That's the largest I've ever installed at that voltage. If I remember correctly years ago we had a 5000 amp service at 480Y/277 volts.
          Rob

          Moderator

          All responses based on the 2017 NEC unless otherwise noted

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            #6
            Originally posted by mbrooke View Post

            What is the perspective fault current on something like that?
            Around 40kA at the transformer terminals. Obviously lower at the end of the conductor runs.

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              #7
              Not bad.
              Our comedian shamelessly joked about a blackout. Talk about dark humor.

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                #8
                Originally posted by infinity View Post
                Our current project has 4-4000 amp services at 208Y/120 volts. That's the largest I've ever installed at that voltage. If I remember correctly years ago we had a 5000 amp service at 480Y/277 volts.
                I’m curious about this.... what type of facility is it? I’m guessing it had to be more cost effective to purchase the transformers from the utility and have them install.


                Sent from my iPhone using Tapatalk
                [COLOR="Blue"]Brought to you by Carl's Jr.[/COLOR]

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                  #9
                  Originally posted by infinity View Post
                  Our current project has 4-4000 amp services at 208Y/120 volts. That's the largest I've ever installed at that voltage. If I remember correctly years ago we had a 5000 amp service at 480Y/277 volts.


                  What type of facility? How many POCO transformers? How many stories?
                  Our comedian shamelessly joked about a blackout. Talk about dark humor.

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                    #10
                    Originally posted by brantmacga View Post

                    I’m curious about this.... what type of facility is it? I’m guessing it had to be more cost effective to purchase the transformers from the utility and have them install.


                    Sent from my iPhone using Tapatalk
                    Me too. Seems like taking service at MV and distributing that around rather than sending that much 208 around from one (or 4) locations would be more efficient.
                    Ethan Brush - East West Electric. NY, WA. MA

                    "You can't generalize"

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                      #11
                      Originally posted by brantmacga View Post

                      I’m curious about this.... what type of facility is it? I’m guessing it had to be more cost effective to purchase the transformers from the utility and have them install.
                      Originally posted by mbrooke View Post
                      What type of facility? How many POCO transformers? How many stories?
                      Apartment complex, two towers, one 26 stories the other 40 stories. About 720 units with a large amenities space. Not sure why they went with a 208Y/120 volt services typically these would be 480Y/277. Could be they didn't want to put in a 480 volt network system which requires space within the building. So we now have about a dozen step-up substations in the service room of the building, some 480 volts some 4160. The 4160 is stepped down to 208Y/120 for apartment power as it goes up the building.
                      Rob

                      Moderator

                      All responses based on the 2017 NEC unless otherwise noted

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                        #12
                        Originally posted by infinity View Post



                        Apartment complex, two towers, one 26 stories the other 40 stories. About 720 units with a large amenities space. Not sure why they went with a 208Y/120 volt services typically these would be 480Y/277. Could be they didn't want to put in a 480 volt network system which requires space within the building. So we now have about a dozen step-up substations in the service room of the building, some 480 volts some 4160. The 4160 is stepped down to 208Y/120 for apartment power as it goes up the building.
                        That sounds like a fun project; I have zero experience with buildings of that size. Is the 480 for HVAC and common area/exterior lighting?
                        [COLOR="Blue"]Brought to you by Carl's Jr.[/COLOR]

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                          #13
                          Originally posted by infinity View Post



                          Apartment complex, two towers, one 26 stories the other 40 stories. About 720 units with a large amenities space. Not sure why they went with a 208Y/120 volt services typically these would be 480Y/277. Could be they didn't want to put in a 480 volt network system which requires space within the building. So we now have about a dozen step-up substations in the service room of the building, some 480 volts some 4160. The 4160 is stepped down to 208Y/120 for apartment power as it goes up the building.
                          You got any help on this project or just you?
                          Ethan Brush - East West Electric. NY, WA. MA

                          "You can't generalize"

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                            #14
                            Originally posted by infinity View Post



                            Apartment complex, two towers, one 26 stories the other 40 stories. About 720 units with a large amenities space. Not sure why they went with a 208Y/120 volt services typically these would be 480Y/277. Could be they didn't want to put in a 480 volt network system which requires space within the building. So we now have about a dozen step-up substations in the service room of the building, some 480 volts some 4160. The 4160 is stepped down to 208Y/120 for apartment power as it goes up the building.
                            I might have done it the same way. If 208 makes the bulk of the load it makes sense IMO. Hate to see a 225kva step down on every floor.
                            Our comedian shamelessly joked about a blackout. Talk about dark humor.

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                              #15
                              190911-2216 EDT

                              Not AC and I never saw it run except in some movies. If memory is correct 240 VDC at about 25,000 A. Maximum distance to any load was probably under 2000 ft. I have no idea of possible short circuit current. There were about 12 of these side by side in the Ford Highland Park Model T plant. I believe installed before 1915. The one remaining unit is in the Henry Ford Museum. It is a huge machine. The flywheel is possibly about 20 ft in diameter.

                              Movie of the generator1919 https://www.youtube.com/watch?v=JIVEKxKDexU
                              the movie that follows this one is 1937 or 8 of the Rouge plant. This is only about 6 years after two of my classmates fathers worked in a very small group that developed the V8. This movie is very much like movies that were shown at the Ford Rotunda in days past.

                              There were many times I climbed around that hugh generator and looked at its construction.

                              .
                              Last edited by gar; 09-11-19, 11:02 PM.

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