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  1. #1
    Join Date
    Aug 2006
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    Electrical question

    I am working on top of an old building in downtown dallas. No where in site is an electrical outlet to run my pump. So the question begs, what do you do to run your vacuum pump after doing an install.

    I am pretty sure it is not legal to create a temporary plug from the Disconnect Box...so what do you do. Do you rent a generator?
    That would be a real drag.

  2. #2
    Join Date
    Jul 2006
    Location
    Anytown USA
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    2,060
    if its 208-230 i just snag a leg of power from the disconnect. If 460 volts our shop has a couple 460-120volt 20amp step down transformers we can use. This is what I do, do only what you feel comfortable doing.

  3. #3
    Join Date
    Sep 2006
    Location
    Rhode Island
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    This is a fairly common problem.... It really makes you appreciate it when you see a newer unit that someone has installed with a 110ac plug at the unit.

    Long extension cord...... I haven’t seen a rooftop unit yet that I couldn’t run a cord to. You may have to run it a long way and even might have to spring for a heavy duty cord or two.

  4. #4
    Join Date
    Nov 2007
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    I am unsure myself
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    widow maker but only as a last resort only done it twice in the last ten years.

  5. #5
    John Culpepper's Avatar
    John Culpepper is offline CHANGE YOUR EMAIL ADDRESS Professional Member*
    Join Date
    Oct 2007
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    Austin Texas
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    1,776
    Here's a glimpse into a unit that I have. No 120v for a few hundred yards and no water for a few hundred yards. Fortunately there is no VD on water.


    I had an electician mount a permanent trans and a GFI outlet on the unit.
    Nemo me impune lacessit.

    How much blood do I have to bathe in to get clean?

    Don't look down on anyone unless you're helping them up.

  6. #6
    Join Date
    Oct 2008
    Location
    Near sacramento, CA
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    Quote Originally Posted by y7turbo View Post
    if its 208-230 i just snag a leg of power from the disconnect. If 460 volts our shop has a couple 460-120volt 20amp step down transformers we can use. This is what I do, do only what you feel comfortable doing.
    I use a temporary pigtail plug and do the same thing.

  7. #7
    Join Date
    Dec 2006
    Location
    Middle Tennessee
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    been using cheater cords and widowmakers for a long time!

    yes, i been shocked by my widowmaker a few times

    when only 480 is available, i run a long cord!



    .

  8. #8
    Join Date
    Sep 2008
    Location
    Western PA
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    Quote Originally Posted by Airmechanical View Post
    been using cheater cords and widowmakers for a long time!

    yes, i been shocked by my widowmaker a few times

    when only 480 is available, i run a long cord!



    .
    Pigtail plug.

  9. #9
    Join Date
    Aug 2006
    Location
    Wisconsin
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    1,504
    Around here on a new install it is code that there has to be 120 installed or you have to be able to get it within 50' of that new unit.. I think in the last 17 years I have only had a problem getting 120 maybe once or twice.
    Buy American! The job you save may be your own.

  10. #10
    Join Date
    Dec 2006
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    Quote Originally Posted by jpsmith1cm View Post
    Pigtail plug.
    use a pigtail on 480



    .

  11. #11
    Join Date
    Jul 2000
    Location
    Dallas,Texas
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    4,953
    If you are going to do this very often, get a 480/240 X240/120 transformer rated 2.5 - 3 KVA. You can make up a receptacle for the low voltage side and leave it wired for 120. Make up a pigtail for the line voltage side and change for 480 or 240 as need dictates. I have used the same set up for years and even run a small wire welder wa-a-a-a-y back on a roof to repair a blower bracket.

  12. #12
    Join Date
    Aug 2006
    Location
    Dallas
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    105
    Thanks for the comments. I will investigate the various options, and see which one suites me best...

  13. #13
    Join Date
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    Quote Originally Posted by wolfdog View Post
    If you are going to do this very often, get a 480/240 X240/120 transformer rated 2.5 - 3 KVA. You can make up a receptacle for the low voltage side and leave it wired for 120. Make up a pigtail for the line voltage side and change for 480 or 240 as need dictates. I have used the same set up for years and even run a small wire welder wa-a-a-a-y back on a roof to repair a blower bracket.
    you will need a pretty big (and heavy) transformer to run that vacuum pump!



    .

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