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  1. #1
    Join Date
    Aug 2002
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    391
    I have a book, Electricity and Controls for heating, Ventilation, and Air Conditioning, from Delmar Publishing. In the sections that deal with start relays, it shows its motors using common connected to a neutral (page 129) when using 120 v and common connected to L2 when 240V. All my other books use common for the 120V line or L1 when using 240V. This is the reverse of everything I have seen when wiring motors, what is up with this?
    The obvious is obvious

  2. #2
    Join Date
    Sep 2004
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    3,157
    On a single phase 220 volt circuit there are three wires. usually a black a red and a white -white wire will be the common- the red will have 110 potential volts -the white will have 110 potential volts -AC-

    so if we are talking about two motors side by side that are 110 volt motors- you would connect the hot red on one motor and the hot black on the other motor and the common wires can all be connected together

    I guess I could have said that the red and the black are two seperate 110v-ac lines-however in the power panel you will find the two hot wires connected to the same breaker

  3. #3
    Join Date
    Apr 2003
    Location
    Eugene, Oregon
    Posts
    1,209
    Originally posted by jrc2905
    I have a book, Electricity and Controls for heating, Ventilation, and Air Conditioning, from Delmar Publishing. In the sections that deal with start relays, it shows its motors using common connected to a neutral (page 129) when using 120 v and common connected to L2 when 240V. All my other books use common for the 120V line or L1 when using 240V. This is the reverse of everything I have seen when wiring motors, what is up with this?
    120v indeed uses common to neutral. 240 common is L1 or L2 as they reffer common as a constant voltage potential and the other line going to a relay to complete the circuit when called.
    Proud supporter of Springfield Millers and Oregon Ducks.

  4. #4
    Join Date
    Sep 2004
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    3,157
    btw page 129 in my book talks about commercial control systems- I have the 6th edition

  5. #5
    Join Date
    Aug 2002
    Posts
    391
    My book is the second edition. I was looking at the motor as if it was a PSC hermetic compressor motor. What I was trying to find is a wiring diagram that shows the wiring for a PTC with a hermetic compressor.

    [Edited by jrc2905 on 04-06-2005 at 02:14 PM]
    The obvious is obvious

  6. #6
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,594
    Many 240 volt multi speed motors will label the white wire as common, the black, red, and blue are your speed taps.

    It just means that the white wire is hooked to the contactor, and which ever speed tap.


    Check out the brown cap wires, ever wonder about the brown wire with the white stripe.




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  7. #7
    Join Date
    Jul 2004
    Location
    West TN
    Posts
    983
    long day.... brains went numb....

    Someone refresh my memory.

    A PTC capacitor is the little blue one with terminals on each end and one on the side right? Has a jumper you put between each end terminal... Think Carrier used them alot about 10-15 yrs ago maybe

    Am I on the right foot?
    Extend to others the grace that God has given you.

  8. #8
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,594
    Carrier,York, and others have used them, York still does.
    There blue, or black.
    Has a heater in it to drop it out of the circuit, after the compressor starts.
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  9. #9
    Join Date
    Nov 2004
    Posts
    2,927
    Originally posted by jrc2905
    My book is the second edition. I was looking at the motor as if it was a PSC hermetic compressor motor. What I was trying to find is a wiring diagram that shows the wiring for a PTC with a hermetic compressor.

    [Edited by jrc2905 on 04-06-2005 at 02:14 PM]
    I dont have the book you are talking about ,but I will attempt to answer anyway. The ptc is connected across the run capacitor.

  10. #10
    Join Date
    Nov 2004
    Posts
    2,927
    Originally posted by wormy
    long day.... brains went numb....

    Someone refresh my memory.

    A PTC capacitor is the little blue one with terminals on each end and one on the side right? Has a jumper you put between each end terminal... Think Carrier used them alot about 10-15 yrs ago maybe

    Am I on the right foot?
    yes,that is right wormy.do you replace them,or pull them off and use a supco hard start?

  11. #11
    Join Date
    Nov 2004
    Posts
    2,927
    Originally posted by jrc2905
    . All my other books use common for the 120V line or L1 when using 240V. This is the reverse of everything I have seen when wiring motors, what is up with this?
    It doesnt matter.(As long as you dont cross them)

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