Hooking up three phase power that is only being used as single phase.

Discussion in 'General Electronics Chat' started by Mark074, Apr 25, 2009.

  1. Mark074

    Thread Starter New Member

    Apr 24, 2009
    3
    0
    Hello,
    I am hoping this question is not to basic, but i am trying to understand this better and i am hoping someone will be able to point me in the right direction so i will be better informed.
    Okay, i am in a 25 year old industrial building in western Canada and have 100 amp three phase service that has only been used as single phase since the building was new. I am installing some equipment with three phase motors and would like to better understand what is going to be needed to have this job done. I am assuming the panel will need to be changed but what i am unclear about is how or what is going to be required to run this equipment and still have the single phase power running the rest of the equipment in the building. I do apologise if the question is to basic, but i am not an electrician although i do understand the basics of a single phase system. I just want to be clear on what is going to be required to hook up my equipment. Trying to google the information gives so many results that it gets mind numbing trying to find an answer. I have attached a pic to let you know what i have and i can list off all the equipment that is getting installed if that helps. I appreciate anyones advice and i am just trying to be informed. Thank you.

    [​IMG]
     
  2. leftyretro

    Active Member

    Nov 25, 2008
    394
    2
    Well looking at your picture it seems to me your getting multiple power sources feeding into the box. The cables coming from the top center and top right look to be single phase power sources that wire to the top of breaker bank on the right.

    The 3 phase power is coming from the large hole in the center left side and wire to the top of the 3 phase breaker and it seems that nothing is presently being powered by the 3 phase breaker as there are no wire leaving the bottom of the 3 phase breaker.

    It's best to let a qualified electrician evaluate your installation as the sources for those power wires will have to be traced to determine the original power sources, their current capacity, etc.

    All you need to tell the electrician is how many total amps of service and how many different load circuits, if there are single phase or 3 phase and their individual current requirements and where there terminal power location will be.

    Lefty
     
    Last edited: Apr 25, 2009
  3. Wendy

    Moderator

    Mar 24, 2008
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    I don't see anything off the breaker for 3ph. Have you measured the input voltages between the legs? What are they?
     
  4. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
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    I respectfully disagree.

    The wires coming in the back are the type commonly running from a distribution panel. Note the neutral implying wye input. We also plainly see red, blue, and black wires from the breakers - standard scheme for single phase 120V power tapped off 120-208V three-phase wye input.

    The top raceways contain 208V outputs from the breakers. First position of the top group of breakers is unused. Second and third positions are phase A and B. Fourth and fifth positions are phase B and C. Sixth and seventh positions are phase C and A. Next three positions (phases A, B, and B) are unused. Not sure what's going on with the two top right breakers (both phase C)... where are the return conductors for them?

    A three phase output from this type of system simply needs three breakers of the appropriate phases feeding the load. Said three breakers should be physically linked so that all trip if one trips. The panel will indeed require upgrade, unless one is willing to give up some existing circuits.
     
  5. Wendy

    Moderator

    Mar 24, 2008
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    I read this as an unused 3 phase breaker, do you disagree?

    [​IMG]

    If that is what it is he could put a second breaker box next to the first, and go from there.
     
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  6. thingmaker3

    Retired Moderator

    May 16, 2005
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    Respectfully, I see it as the main input breaker. There should be three bus-bars fed by it, hiding behind the green plastic. They can just barely be seen to the left of the breakers they feed in turn.
     
  7. Wendy

    Moderator

    Mar 24, 2008
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    I've been wrong before, so I'm not sweating it. Only the OP can see the total setup in context. I'm still curious what AC voltage the three heavy wires are compared to each other, and to ground.
     
  8. leftyretro

    Active Member

    Nov 25, 2008
    394
    2
    Well my eyes see what I already stated and I've seen hundreds of power panels at the refinery I worked on. However neither of us are in a position to be able to prove our statements. A qualified electrican is required in either case and he or she will find out the true state of that panel.

    Again I feel the 3 phase breaker has wires feeding in but no loads are wired out and there are no 'hidden' buss bars under such a haphazed layout as that one. But then again my eyes are on the older side, I don't even see the color green anywhere except a few wires! ;-)

    Lefty
     
    Last edited: Apr 27, 2009
  9. Pich

    Active Member

    Mar 11, 2008
    119
    4
    Mark
    From what I see in the picture it ia a 3 phase 4 wire panel 208/120 volts, all that's needed is to get the manufacturer of the panel and purchase a 3 phase breaker with the proper amperage rating for your addition. Problem may be that there may not be enough space for the breaker in the panel.
     
  10. greendean

    Member

    Dec 20, 2008
    19
    0
    If you have to ask.
    Hire someone.

    If you don't understand what you looking at in that panel than just close it up and walk away.

    I am an industrial electrician and I am begging you to just please walk away.
     
  11. thingmaker3

    Retired Moderator

    May 16, 2005
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    I concur whole-heartedly!
     
  12. Mark074

    Thread Starter New Member

    Apr 24, 2009
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    Thank you for your input gentleman. Indeed the three phase power is the power source and that is a 100 amp breaker. The other larger cables coming out of the panel are for a compressor and an oven. I am not doing the work myself, i am just trying to be informed so i can understand the electrician when he tells me what he is going to charge me to do the install. I always have felt that it is wise to know what you are dealing with instead of going in blind hoping that the guy you are dealing with is honest. I just have never dealt with three phase power before and want to learn about it. I am not the kind of person who believes if you have to ask, forget about it. To me that is just putting blind faith into someone you don't know. I am just not sure how this works with the three phase power coming into the panel and how it is hooked up so that it is single phase. Does this mean that there is the possibility of being able to use 100 amps of service on 3 different legs? I guess what i am really wondering is it possible and legal to hook up another panel to wire up the three phase breakers and just leave this single phase panel alone? Is there a difference between single phase panels and three phase ones? Can anyone point me to a link where i could see pictures of similar systems and or read up on this? Thanks again for all the replies, i mean't to get back sooner but have been very busy.
     
  13. greendean

    Member

    Dec 20, 2008
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    You have a 3-phase panel there.
    There is nothing single phase in there.
    You have single pole breakers coming off one of three busbars.

    The main breaker there (100 amp) is feeding 3 bus bars behind that plastic cover. Then on the right side of the panel the branch circuit breakers are connected to the bus bars. Depending on the circuits you are using a one, two or three pole breaker to power them.

    All you would have to do in that panel to add a 3 pole motor control would be to just install a 3 pole breaker in that spot i see with 3 spots open.

    Very very simple.

    Sorry about my "just walk away" answer before.
    People really scare me when they start opening panels on thier own.
     
  14. Mark074

    Thread Starter New Member

    Apr 24, 2009
    3
    0
    Thank you for your answer. So in other words, as long as there is enough room in there for the 3 pole breaker the panel is fine. I just was not sure how you got single phase power out of a three phase supply. No problem on the walk away comment, people always should do things safe and professional. I just am trying to know what the electrician will be talking about before i have one come over.
     
  15. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
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    The top feed has the red/black/blue wires, though it appears blue wire (white after a couple inches) is connected to the ground bus,though it is difficult to say for sure. The heavy gauge 3 phase input at left has a ground wire (grey), also connected to the ground bus. This implies the top input is a single/split phase input, but NOT with certainty.

    I can only strongly urge calling a couple electricians to get independent quotes.
     
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