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Thread: 480 Volt Single Phase

  1. #1
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    Cool 480 Volt Single Phase

    I have been under the impression that 480 is only three phase. I have a Parking Lot light with 480 volts........only two phase wires and one ground. Is this right or should I have 3 phase wires and a ground........no neutrals are run to the pole. The breaker feeding these lights are 2 pole 20 amp.

  2. #2
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    There are plenty of things that utilize 480 volt single phase, site lighting is one common example.

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    Quote Originally Posted by InspecThis View Post
    I have been under the impression that 480 is only three phase. I have a Parking Lot light with 480 volts........only two phase wires and one ground. Is this right or should I have 3 phase wires and a ground........no neutrals are run to the pole. The breaker feeding these lights are 2 pole 20 amp.
    480 volt street lighting. One phase wire, 1 neutral, 1 ground.
    Unlimited Electric Contractor/Standard Electric Inspector/Traffic Signal Inspector/Highway Lighting and Level One Traffic Signal Installer.

    I know you believe that you understand what you think I said but I'm sure you realize that what you heard is not what I meant.

  4. #4
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    There are a number items that utilize single phase 480, along with the mentioned site lighting, there are pumps, fan motors, some commercial cooking equipment, transformers, to name a few.

    Roger
    Moderator

  5. #5
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    Quote Originally Posted by Cavie View Post
    480 volt street lighting. One phase wire, 1 neutral, 1 ground.

    Lets not confuse him, the 480 volt system he is using does not have a neutral at the poles and most will not.

    The system you work on is unusual for NEC applications.

  6. #6
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    Quote Originally Posted by iwire View Post
    Lets not confuse him, the 480 volt system he is using does not have a neutral at the poles and most will not.

    The system you work on is unusual for NEC applications.
    Just trying to show a 3rd system he didn't know about. I learned of at after only 40 years.
    Unlimited Electric Contractor/Standard Electric Inspector/Traffic Signal Inspector/Highway Lighting and Level One Traffic Signal Installer.

    I know you believe that you understand what you think I said but I'm sure you realize that what you heard is not what I meant.

  7. #7
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    Quote Originally Posted by Cavie View Post
    Just trying to show a 3rd system he didn't know about. I learned of at after only 40 years.



    So you got in the trade at 5 years old.

  8. #8
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    Quote Originally Posted by InspecThis View Post
    I have been under the impression that 480 is only three phase.
    Just about any voltage could be supplied from, and/or provided as single or three phase. It's true that 480v is a common commercial/industrial 3ph service voltage, and as either Delta or Wye.

    I have a Parking Lot light with 480 volts........only two phase wires and one ground. Is this right or should I have 3 phase wires and a ground........no neutrals are run to the pole. The breaker feeding these lights are 2 pole 20 amp.
    It's really no different than obtaining 208v 1ph from a 208Y/120v 3ph supply, or even from a (rare, but possible) 208v Delta 3ph secondary. The neutral makes bonding convenient even if the load doesn't need it.

    Your supply could be either Delta or Wye, and it may be single or three phase. It doesn't really matter; just treat every conductor as ungrounded. (The panel the 2-pole breaker is in has all the answers. )
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  9. #9
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    Quote Originally Posted by iwire View Post
    So you got in the trade at 5 years old.
    I'm kinda close; I wired our shed when I was around 10 or 11.
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  10. #10
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    Quote Originally Posted by LarryFine View Post
    I'm kinda close; I wired our shed when I was around 10 or 11.
    DIY work does not count .... if it did I got you beat.

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