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Compressor Wiring

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  • Compressor Wiring

    I have a new air compressor to hook up, calls for 230 volts, 14.7 amps. I have a piece of equipment I just removed that used 480 volt 3 phase on a 20 amp breaker. It had 3 hots and a ground. If I only use 2 hots and the ground, does that leave me with a proper circuit for the compressor?

  • #2
    Re: Compressor Wiring

    NO! If you hook up a 230V motor across a 480V source you will let the smoke out of the motor and as many of us have experienced - all electrical devices must retain their full load of smoke in order to function properly.

    Your motor is designed to run on household power where the 2 'phases' are 180° out of phase.
    Last edited by wbrooks; 07-04-2008, 09:11 PM.

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    • #3
      Re: Compressor Wiring

      No and going from neutral to one of the hot won't normally work either. Depending on the electrical system many large places have what's called 277/480 Volt type Y electrical service. Only if you had a center tapped transformer could you maybe have 240 + 240 Volts from neutral to each end. Such is a rare situation. In most cases they have 3 step down transformers with 480 Volt primary and 120 Volt secondary windings. In some cases they may have the electric company setup a second service coming in that's 120/208 Volts Y three phase or they may go for 120/240 single phase. In any case it has to be kept totally separated.

      If what you have is in fast 3 hots with 480 Volts from L1 - L2, L1 - L3 and L2 - L3 then you must connect up a step down transformer from any two hots where it is made as a 480 primary and 240 Volt secondary transformer. It must be rated with a high enough KVA rating to handle the load.

      Bottom line: Save equipment, the building and maybe some lives. Call in a good licensed electrician to help with this. You got to know exactly what Voltages are in the building and where. Do not try to connect up small motors to the wrong Voltage or it will be KABOOM and FIREWORKS time.

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      • #4
        Re: Compressor Wiring

        depending on the situation it may be jsut as easy to replace the motor on the compressor (if the 240 volt is not easy to be found),
        replace with a 3phase motor that will run on 480 volts.

        you will jsut have to do some figures and compare, on what needs to be done to get the proper voltage, or the cost of the motor and starter, or if you have some thing used, check the RPM of the motor and if difference adjust pulley size.

        depending on the compressor and dealer if new you could talk to the distributor/dealer and see you could trade it for one of the proper motor and voltage set up for what you have available.
        Push sticks/blocks Save Fingers
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        • #5
          Re: Compressor Wiring

          Take the compressor back and exchange it for a 3 phase 480v one.
          The 3 phase motors are much more durable and I think more efficient.

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