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  1. #1
    Join Date
    Apr 2004
    Posts
    158

    Confused Trouble with primary winding on transformer

    Why would the primary winding open 2 days in a row?
    This customer had major electrical issues a few months ago but he claims
    He had them fixed. The problem is on a 4 yr old Carrier but I think its in
    His wiring. Any help is appreciated, thanks.

  2. #2
    Join Date
    Jun 2004
    Location
    Eugene, Oregon
    Posts
    1,018
    Please describe the major electrical issues. I don't think I've ever seen the primary windings of a xfmr go.

  3. #3
    Join Date
    Jun 2012
    Location
    Fayetteville, NC
    Posts
    286
    The last few i have seen other than direct shorts have been low voltage coils with 0 resistance ie, contactors

  4. #4
    Join Date
    Apr 2004
    Posts
    158
    He has half the house on the same circuit as the furnace. A few months ago the breaker kept tripping and the kitchen lights were blowing out. He said electrician found some bad nuetral connections but didnt run seperate line for furnace only. I told him the furnace needs its own breaker, but this guy was a contractor for 50 years and knows everything.

  5. #5
    Join Date
    Sep 2012
    Location
    Central Florida
    Posts
    885
    The only times I have seen the primary side of a transformer blow is when it has taken to much voltage. Some one in our shop will use the tap for 208 on a unit that's meant to run on 460. Have you verified correct voltage for the system?

  6. #6
    Join Date
    May 2005
    Location
    Michigan
    Posts
    124
    Codes everywhere require that, the heating equipment be on it's own desingnated circuit.
    If half of the house is also on heating circ. " anything goes " as far as what the cause could be.

    You told the customer the right thing, " Put the equip. on it's own circ. "

    When I give customers my pro. advice, and they still " Don't listen "

    Many times I " FIRE EM' "
    I may not be the sharpest knife in the drawer, but compared to some I'm a razor...

  7. #7
    Join Date
    Nov 2006
    Location
    Southeastern Pa
    Posts
    18,391
    Quote Originally Posted by mike d373 View Post
    He has half the house on the same circuit as the furnace. A few months ago the breaker kept tripping and the kitchen lights were blowing out. He said electrician found some bad nuetral connections but didnt run seperate line for furnace only. I told him the furnace needs its own breaker, but this guy was a contractor for 50 years and knows everything.
    Bingo.

    This buzzard is using multiwire branch circuits. When a neutral opens, the voltage goes from 120 to 240 on whatever is connected.

    That's why he is losing transformer primaries.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

    AOP Forum Rules:







  8. #8
    Join Date
    Aug 2012
    Location
    NE wisconsin
    Posts
    402
    You've told him what needs to be done to correct the problem, maybe after he buys 15 or 20 xfmers from you at full price he might decide to fix the real problem.

  9. #9
    Join Date
    Apr 2004
    Posts
    158
    Unfortunately hes still in warranty. I told the boss whats going on and hes gonna have to tell him because he doesn't want to hear it from me. Yes i had 118 volts to furnace.

  10. #10
    Join Date
    Aug 2012
    Location
    NE wisconsin
    Posts
    402
    Failure to correct the real problem will usually void any warranty, check with the warranty provider. At least that's what I would tell the customer.

  11. #11
    Join Date
    Nov 2006
    Location
    Southeastern Pa
    Posts
    18,391
    Quote Originally Posted by mike d373 View Post
    Unfortunately hes still in warranty. I told the boss whats going on and hes gonna have to tell him because he doesn't want to hear it from me. Yes i had 118 volts to furnace.
    Loose neutrals on multiwire circuits can still read 120 most of the time. It's when that contact breaks...for just a moment......
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

    AOP Forum Rules:







  12. #12
    Join Date
    Mar 2012
    Location
    Birmingham Al
    Posts
    232
    Quote Originally Posted by timebuilder View Post
    Bingo.

    This buzzard is using multiwire branch circuits. When a neutral opens, the voltage goes from 120 to 240 on whatever is connected.

    That's why he is losing transformer primaries.
    I fully agree with this. i got the ---- shocked out of me by a "dead neutral" because of a back feeding circuit. same situation with the transformer. interesting that the board in the unit will take that.

  13. #13
    Join Date
    May 2011
    Posts
    79
    Quote Originally Posted by mike d373 View Post
    He has half the house on the same circuit as the furnace. A few months ago the breaker kept tripping and the kitchen lights were blowing out. He said electrician found some bad nuetral connections but didnt run seperate line for furnace only. I told him the furnace needs its own breaker, but this guy was a contractor for 50 years and knows everything.
    BTDT. Last one was at a home that a young couple lived in. They had just bought the house from a guy who was a handyman legend in his own mind. Why wouldn't you wire your entire finished basement and half of your kitchen on the same circuit as the furnace?

    When I told her on the phone what was going on (nobody home while I was there), she said she wasn't surprised due to all the other things that had gone wrong since she bought the place, and that it was probably no coincidence that the fridge and disposal had stopped working too.

    "*blink blink* Well, I left the bill for our time on the kitchen table. Call an electrician."

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