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  1. #14
    Join Date
    May 2013
    Location
    Utah
    Posts
    57

    Conduit and Ground Faults

    Many years ago I was dispatched to a Lennox GCS series unit that was down. I found the main breaker tripped on a 480V 3 phase unit, and without an obvious good reason. So I was following some kind of intuitive sequence as I often do and I had the system running with the blower panel off as I was following something down. The conduit entrance to this machine came through the blower section as often they do. So what it comes down to is an intermittent Phase to Ground fault in that conduit run, near enough to the RTU to see a flash and hear it. Its an intermittent arc at potential that is not dead in contact with ground. Sometimes it would not trip the breaker.
    I then had to " show " the attending electrician the fault because he did not " get " why he was being asked to replace the wiring back to the nearest junction which in this case may have been the entire run. After he saw the demonstration he understood I knew what I was talking about.
    Around the same era I was in a tight crawlspace repairing a leak on top of a walk in cooler by flashlight. When I cut the suction line I got lit up with electricity. I broke out my meter and found about 90V between the now separated suction line. I was " hot " to say the least. I seem to recall asking the boss to come by the job and file through circuit breakers while I remained reading the potential that had got my attention. It turned out to be the box lighting circuit. Now start to imagine how everything was grounded with this system, or not. As far as wiring goes I personally never assume it is right. I have corrected major control issues on very large and expensive systems that were not wired right from the get go.

  2. #15
    Join Date
    Nov 2011
    Location
    St. Louis
    Posts
    3,650
    Quote Originally Posted by cws110 View Post
    Did it have the old Carlyle compressor? I have seen that style of Carrier and didn't think they were even as new as 77. It seemed like with those units- if they ran for four or five years then they would run forever.
    I wouldn't know an old Carlyle if it bit me on the nose. Two years with a Carrier dealer and I've seen plenty of mid to late 80's units. This was unlike any Carrier I've come across so far - so I'm thinking at least mid 70's.

    No doubt it's impressive the way they used to make them. However when I repair them, I make damn sure they understand I'm standing behind my repairs only. All bets off concerning the rest of the system, regardless of whether it's amping, ohming, charged, performing etc properly when I leave.

    My last on call week I took a call on the way to another about 9:30 PM or so. The gal said her unit stopped "pumping" again. I asked "again"? She then told me we were out a few days ago and read me the ticket - 521 kit added and run cap changed. She can tell the fan is spinning but doesn't hear the rumble of the compressor and she knows enough to feel the lines to see that they are neutral in temperature. I ask how old it is and she says about 23 years or so. I tell her it might be done then if the fan is spinning like it normally should and the compressor is not turning over; and she becomes quite upset. "Why did they make the repairs if this could happen so soon!?"

    Good question. The tech didn't even broach the subject of replacement nor warn her of this possibility. Just took the money and road off into the sunset with another glorious 521 and run cap notch (20 minutes and what...five wires?) on his toolbelt.

    The customer was not served well in this instance and it's not an isolated incident. And in her mind we are not to be called again or recommended to anyone.

  3. #16
    Join Date
    Dec 2012
    Location
    columbus, OH
    Posts
    2,193
    I was thinking temporarily wire it to observe its operation then decide if a whip is in the customers best interest.

  4. #17
    Join Date
    Feb 2010
    Location
    butler pa
    Posts
    1,073
    being round..those are easy to roll to the truck when changed out...my neighbors still have one chugging away and not missing a beat

  5. #18
    Join Date
    Jan 2006
    Location
    McQueeney, Texas
    Posts
    4,033
    Cut the conduit back 3" and just wire nut on another wire directly to the condenser with no conduit.
    Around here, some idiots think that is ok.

  6. #19
    Join Date
    Dec 2007
    Posts
    4,764
    Quote Originally Posted by walterc View Post
    Cut the conduit back 3" and just wire nut on another wire directly to the condenser with no conduit.
    Around here, some idiots think that is ok.
    at least they use wire nuts!!!
    The Food Stamp Program, administered by the U.S. Department of Agriculture, is proud to be distributing the greatest amount of free meals and stamps EVER.
    Meanwhile, the National Park Service, administered by the U.S. Department of the Interior, asks us to "Please Do Not Feed the Animals". Their stated reason for this policy "... the animals become dependent on handouts and will not learn to take care of themselves."
    from an excerpt by Paul Jacob in Sun City, AZ

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