Strange results with 120VAC house wiring

Discussion in 'General Electronics Chat' started by Louis Teceno, May 15, 2015.

  1. Louis Teceno

    Thread Starter New Member

    May 15, 2015
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    I hope this is the right place to post this question. It may be long but the details need to be there.

    Ok, had a new guy I hired at my apartment community. He was wiring up some outlets and switches and when finished, started checking everything. He got to the last switch and when he turned it on, heard an arcing noise and then the power went out. Not the whole unit, just one 15 amp breaker. He turned the switch off and turned the breaker back on. He immediately called me and I went to look at it.

    When I showed up, he mentioned that the dining room light was not working but was working before. With all the breakers on. I checked all the outlets and found a series of outlets out, presumably 9n that same circuit that arced earlier. I isolated the circuit that was affected by no power and also found the problem with what caused the arcing. An outlet on a switch but also had a neutral and a hot to another outlet. So when the switch was flipped, the hot and neutral were connected.

    Hopefully, I haven't lost you yet. So where we stand so far is, an outlet short causing an arc and a breaker to trip. With all breakers on, some outlets and lights don't work. Isolated those outlets and lights to a specific 15 amp breaker. Just that breaker on, all others off, nothing has power through out unit.

    Now, I checked for 120 to neutral and ground at the breaker panel on this specific breaker and I have 120 volts. So since I had no voltage anywhere, I decided to do a continuity test to every black wire coming in everywhere, at every box, switch or outlet, and found one wire with continuity to this specific breaker which was wire nutted together to two others. However, I did not get 120 volts. Please tell.me what the hell is going on. How is it possible to have continuity between two points with one end showing 120 volts but the other end nothing? And this is where it gets even more weird. When I went to go check for 120 volts, I forgot to switch from continuity to volts and there was continuity between ground and hot! While there was a supposedly 120 volts flowing through this peticular line.

    Im usually pretty good at troubleshooting electrical, but this one is throwing me for a loop. I even cut a hole in the wall and pulled the culprit wire out of the box completely and checked continuity to the box again and still it shows continuity. But.now there is.no continuity from the wire in the box to the breaker, which there was before.

    What am I missing??
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    For starters, please provide a more descriptive title when you start a thread so that it provides readers with the nature of your request.

    This would be a better title: "Strange results with 120VAC house wiring"
     
  3. MrChips

    Moderator

    Oct 2, 2009
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    It is possible that before the breaker tripped the current surge weakened one or more of faulty connections. You will have to go and check every connection on all live and neutral wiring and connections in the suspect line.
     
  4. Louis Teceno

    Thread Starter New Member

    May 15, 2015
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    Thanks for the input
     
  5. Louis Teceno

    Thread Starter New Member

    May 15, 2015
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    I looked for a way to edit the title, is this possible?
     
  6. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Probably a decent electrician.;)

    Probably the only way is to try and trace the offending circuit and its course remove wire nuts and check voltages, Strange seems that you have lighting circuits and plug circuits off the same breaker?
    Max.
     
  7. Louis Teceno

    Thread Starter New Member

    May 15, 2015
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    My main concern is how a 120 V wire can show continuity to ground and not trip the breaker? I will probably end up calling an electrician, however I do understand the basics of electricity and I know that thats not right. Isually after calling an electrician the problem becomes clear and I would have figured it out if I just spent a little more time on it.
     
  8. MrChips

    Moderator

    Oct 2, 2009
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    Looks like you have a short across your wires and a break in the wire to the live panel.
     
  9. studiot

    AAC Fanatic!

    Nov 9, 2007
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    1) Max is right get an electrician

    2) Max is right get an electrician

    3) Max is right get an electrician

    I would be also worried about the mechancal security of connections made by anyone who managed to cross wire lighting and power circuits, line and neutral connections. The connections may work for a while, but they may also be loose.
     
  10. Louis Teceno

    Thread Starter New Member

    May 15, 2015
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    Every apartment complex I have worked at has had lighting and power circuits mixed. It doesn't come as a surprise to me.
     
  11. shortbus

    AAC Fanatic!

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    As did every house I've ever lived in. Except in kitchens and basements where appliances are involved.
     
  12. strantor

    AAC Fanatic!

    Oct 3, 2010
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    Ditto. In my house if something plugged in trips a breaker, lights go out.

    Youre confused that when you measure "ground" to a certain wire at one end you read 120v, but when you measure "ground" to that same wire at the other end, you get no reading. Only explanation i have is that you only really have a tru GROUND at the end where you measure the voltage. The other end must be missing its ground. You probably vaporized the ground wire somewhere, or wingnut forgot a wirenut somewhere. Check from the ground in your panel to the mystery hot wire and i bet you read 120v


    Its possible the problem is that
     
  13. MaxHeadRoom

    Expert

    Jul 18, 2013
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    I know around here it is considered bad practice to mix lighting and outlet circuits.
    I haven't come across it in homes newer than ~30-40 yrs.
    Max.
     
  14. dl324

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    Mar 30, 2015
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    My house is 40 years old and outlets on one wall in my living room and the lights and outlets for the master bedroom/bath and hall bath are on the same circuit. Two people running hair dryers at the same time trips the breaker. Crazy, but that must have been code back then. Did a kitchen remodel 20 years ago and the electricians didn't put alternate outlets on different circuits.

    To not be completely OT, agree OP should get a competent licensed electrician to check the work of the incompetent one... Electricians license and contractors license don't mean squat. Had 2 electricians wire my transfer panel incorrectly and I didn't find out until I fired up my generator during a power outage. I was energizing the utility lines (momentarily).
     
    Last edited: May 16, 2015
  15. MrChips

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    Oct 2, 2009
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    Supposedly a "qualified" electrician wired my house. They cut the ground on the GFI breaker because they were too lazy to look for a short between ground and neutral behind one of the outlets.
     
  16. strantor

    AAC Fanatic!

    Oct 3, 2010
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    Come to think of it, I also have outlets that are on light switches. It's become normal for me so i dont think about it any more. But i have some light switches around my house that are taped in place because they undesirably control outlets. Like the light switch for my living room lights, which also turns off my DVR. Or the light switch for my back porch lights which turns off an outlet in the garage. My house was built in 1970. The code it was built to (if it ever was built to any code) is probably considered totally inadequate today. And I'm sure there have been several rogue modifications in the past 45 years (none by my hand).
     
  17. dl324

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    One (of 3) electricians working on my kitchen remodel installed a larger power panel. When he reconnected the existing wiring, he forgot to hook up my water heater. His apprentice was a holy terror in my attic. She didn't know to walk on the rafters and I'm surprised she didn't fall through the ceiling.
     
  18. shortbus

    AAC Fanatic!

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    Many houses from that era and a little earlier had a switch controlled outlet with the switch next to the front door. The outlet was supposed to be used for a table lamp.
     
  19. strantor

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    Thar makes sense, but still there are many clues I've encountered that makes me think this house was assembled by people picked up from the Home Depot parking lot (or wherever they congregated in 1970). The list is long, but a couple examples: There is not a single wall or doorway which is straight. There are no two studs placed the same distance apart. There are some doorways that don't have the metal flashing on the corners; they were just heavily taped and bedded.

    I have been told that this neighborhood (and all this whole area) just appeared overnight almost; the area was expanding incredibly fast there were not enough workers to build everything. I assume that also means there were not enough inspectors. I would be surprised if it were ever built to code and/or thoroughly inspected for adherence to code.
     
  20. KJ6EAD

    Senior Member

    Apr 30, 2011
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    That's what I call "70's opium den lighting design". It's characterized by no ceiling light fixtures, one receptacle per wall and a switched outlet for your lava lamp. One of my friends had a condo like that before he hired me to fix it. Now his neighbors ask how he has so much light since their condos were built the same.
     
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