480VAC to 277V without transformer?

Discussion in 'General Electronics Chat' started by barnabus, Sep 17, 2013.

  1. barnabus

    Thread Starter New Member

    Sep 17, 2013
    3
    0
    Have an application that requires 277VAC, but only have 480VAC. I know I can get 277VAC by going from one leg to ground. Is this appropriate? Do I need a transformer? What happens if ground is lost - or do I need to worry about ground lost?
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,548
    2,373
    You should NEVER use Earth Ground as a circuit conductor, for mains power, anyway.
    If by one leg to ground you really mean neutral, and it is a valid neutral as per the electrical code then it would be OK, e.g. a transformer star point has been earth grounded at the transformer, and a separate conductor set up as the neutral.
    Ensure the total load connected to your supply is not sufficient to unbalance the other phases.
    Max.
     
  3. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,770
    970
    You should hire a competent electrician ASAP.
     
    #12 likes this.
  4. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,800
    1,104
    Presumably your 480V AC is a 3-phase supply and you are considering using the voltage from one phase terminal to neutral?
     
  5. barnabus

    Thread Starter New Member

    Sep 17, 2013
    3
    0
    Yes, this is correct. Wondering where I get a valid neutral. Normal installations that I see have three phases and a ground. Or - am I missing that they all have a neutral? Or - is the neutral not being brought to me?
     
  6. #12

    Expert

    Nov 30, 2010
    16,298
    6,810
    You have to understand the difference between "ground" and "neutral", then go look at the wires, maybe even verify with a volt meter, to see if a neutral is provided. We can't see it from here, so you have to do it. And be really careful! This kind of voltage will blow your fingers off and turn a Harbor Freight voltmeter into a ball of flames.
     
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,548
    2,373
    Are you in N.A.?
    If you have three 3 phase conductors and a ground, it would most likely mean that the Neutral point has been Earth grounded, but if this is the case, you cannot use this as a conductor, a separate neutral would have to be ran from this star point or ground point origin.
    You need to determine exactly what the supply consists of to progress any further.
    Max.
     
  8. gerty

    AAC Fanatic!

    Aug 30, 2007
    1,153
    304
    480 3 phase with a WYE connection will have a neutral, 480 DELTA does not have a neutral. You need to find out which you have. On some service panels, if you open the door there is a placard stating whether it's delta or wye.

    Failing that, the removal of the panel cover, by someone qualified, will reveal a neutral if there is one there.
     
    GopherT likes this.
  9. barnabus

    Thread Starter New Member

    Sep 17, 2013
    3
    0
    I am in North America. Is 480V Wye uncommon in North America - Michigan? I understand the difference between ground and common also - essentially that's why I'm asking the question. Thanks for your help on this.
     
  10. gerty

    AAC Fanatic!

    Aug 30, 2007
    1,153
    304
    WYE is very common. Where I worked last we had 480 WYE and used 277 volts for all the plant lighting. Where I work now we have 208 WYE, if anything I have seen less DELTA connections.

    edit: did you check the panel for the specs?
     
Loading...