Advice for troubleshooting a bad circuit

Discussion in 'Electrical Forum discussion & Blog' started by mnalep, Oct 11, 2009.

  1. mnalep

    mnalep Member

    Joined:
    Apr 29, 2008
    Location:
    Redford, Michigan
    Hello,

    I was hoping to find some advice to help me trouble shoot a portion of my home's wiring circuit that has stopped working.

    I have lost power to 7 lights. They are the font/back porch lights, basement light, stairway, hallway, 1 bedroom, bathroom, and the living room. I still have power to other lights, and all receptacles in the house.

    The fuse looks good.

    This started when I went to put a new bulb receptacle in the front porch light.

    The old one stopped working, and when I looked at it the socket seemed to be disintegrating.

    I bought a new socket, and attempted to wire it in. I believe what I did was accidentally cross the 2 wires to the socket when I was pushing it back in. (The wires were bare, and I should have fixed that also).

    The light came on for a bit, until I pushed the socket in the lamp fixture, and twisted it. the light went out, the fuse blew.

    After I put a new fuse in, the porch light, and now the other lights stopped working.

    I pulled the 2 switches in front of the porch light (and living room light) thinking that perhaps they had shorted also. But the 2 switches test ok (with both a multimeter, and a continuity light).

    I was thinking the next thing to do was insure there is power to the fuse in the service panel. Then pull the porch light off, and look it over, and then test for continuity at the wires leading from the switch to the porch light.

    Then if that all looks good, test the remaining switches that are on the circuit that is not working for continuity.

    Is this a good plan for troubleshooting this bad circuit?

    If I get that far, and still have not found a problem, what should I test next?

    Can I test for continuity on the wires from room to room?

    Matt
     
  2. Thatguy

    Thatguy Homeowner

    Joined:
    Aug 27, 2008
    Occupation:
    A bounty hunter like in "Raising Arizona"
    Location:
    MD
    A bad connection or wirenut has failed to an open circuit.

    Put a turned-on radio in one of the non-functioning sockets, and poke around in the socket boxes with a wooden dowel upstream of this one.
    If the radio starts playing you are near the failed connection.
     
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  4. mnalep

    mnalep Member

    Joined:
    Apr 29, 2008
    Location:
    Redford, Michigan
    How do I find/determine which boxes are upstream (or downstream) of each other? (Without tearing walls apart)
     
  5. Billy_Bob

    Billy_Bob In the Trades

    Joined:
    Apr 2, 2008
    Wire costs money. When they wire homes, they *usually* try to do so in a manner which uses the least amount of wire.

    So typically electrical panel to closest light, then to next closest light, etc. down the line.

    But this is not always the case and things are not always in a straight line.

    There could also be outlets on this circuit. Maybe the problem is at an outlet or light which works when power is on, but it is not passing the electricity down the line from that point due to a poor connection.

    And maybe you can go into the attic (if accessible) and see where the wires go?

    Also you can get a tone generator and listening device which will allow you to trace wires in the walls. Like this...
    (Sold at electric supply or home improvement stores.)

    [​IMG]
     
  6. mnalep

    mnalep Member

    Joined:
    Apr 29, 2008
    Location:
    Redford, Michigan
    thatguy,

    I'll have to look for a small radio. Not sure what I did with my old one.


    BillyBob,

    That looks like a good tool to have. Sort of like a studfinder? I have Home Depot near me, I'll go and price it out. Are they expensive?

    I don't have an attic above the rooms, there is an upper flat above me, and it has the attic above it.
     
  7. Billy_Bob

    Billy_Bob In the Trades

    Joined:
    Apr 2, 2008
    Yes it is sort of like a stud finder in that the stud finder detects things inside the wall.

    With the tone generator, you attach the tone generator to *disconnected* electrical wires hot/neutral (don't use ground) at the main panel, then you can use the listening portion to follow the wires through the wall.

    You may be able to just disconnect the hot, connect just one tone generator wire to that, and trace that in the walls.

    But you wouldn't want power on, this would damage the tone generator. And you wouldn't want the wires in the circuit connected, because then it would send the tone out on ALL wires including wires from other circuits. You want to trace just the wires on that circuit.

    And same thing with ground. Ground goes everywhere! And might also "ground out the signal".

    This is an "inductive pick-up".

    As to price, they are not cheap, but worth every penny if you need it.
     
  8. Thatguy

    Thatguy Homeowner

    Joined:
    Aug 27, 2008
    Occupation:
    A bounty hunter like in "Raising Arizona"
    Location:
    MD
    For working outlets there is a way to determine outlet order using a voltmeter and a 10A, 120v load [like a hair dryer].
    It comes in handy for putting GFCIs upstream of outlets you want protected.
     
  9. jbfan74

    jbfan74 Electrical Contractor

    Joined:
    Jun 14, 2007
    Occupation:
    Electrical Contractor
    Location:
    Newnan, GA
    Always look at the last place any work was done. In this case, it sounds like the light.
    Did you replace the complete fixture, or repair the old fixture?
     
  10. mnalep

    mnalep Member

    Joined:
    Apr 29, 2008
    Location:
    Redford, Michigan
    Well I found the problem. The fuse and fuse outlet on the service panel that controls the wiring was good.

    The problem was a blown fuse, in a second panel! This second panel fuse, and the fuse on the main panel must have both blown when I accidentally crossed the hot and neutral wires going to the porch light. What surprises me is that there are 2 fuses, that both control parts of the same circuit. The fuse in the main panel controls 7 lights on the circuit. The fuse on the sub panel controls at least 2 of the same lights (porch and living room).

    Is this abnormal, or what?
     
  11. Billy_Bob

    Billy_Bob In the Trades

    Joined:
    Apr 2, 2008
    Fuses in homes are typically involved with older wiring. And over the years there may have originally been a smaller home and one electric panel, then an addition to the house, then an additional electrical panel added.

    And anyone could have done anything with the wiring over the years! Basically one fuse would protect everything and another fuse under the domain of that fuse would protect a subset of that. Not either/or.

    So typically there would be a main fuse for the whole house, then connected to that fuse might be a smaller fuse which would protect a circuit for the kitchen. If the main fuse blew, the whole house would go out, if the kitchen circuit fuse blew, just the kitchen circuit would stop working. (Gets a bit more complex than that, but that is the basic idea.)

    Circuit breaker panels are more safe in that you can't accidentally touch a live conductor like when replacing a fuse nor can a homeowner easily replace a breaker as could be done by replacing a fuse with the wrong value fuse.

    If you have some extra money laying around and want to sleep better at night, might want to have an electrician look at your fuse panels. Perhaps have them replaced with modern circuit breaker panels.

    Also if you have say just 1 circuit in the kitchen and have fuse blowing problems due to overloading, you can also have a couple of extra circuits run to energy hogs like a microwave or refrigerator. This will off-load the existing circuit.

    And you could always add extra new circuits later.
     
    Last edited: Oct 13, 2009
  12. mnalep

    mnalep Member

    Joined:
    Apr 29, 2008
    Location:
    Redford, Michigan
    I would not mind getting a circuit breaker in there, but I'd have to do it myself, and would need some good advice to proceed with that. Any book you'd recommend that could help, or educational web site, or something?
     
  13. Billy_Bob

    Billy_Bob In the Trades

    Joined:
    Apr 2, 2008
    I would say if it was an all new installation, then maybe reading 3 book length things on this cover to cover would get you to where you could do it safely and pretty much ok. (As well as having it inspected by an electrical inspector.)

    But with replacing a fuse box, no telling what is not right or what is dangerous and needs to be fixed along with installing a breaker panel. For example too high of amperage fuses may be installed, installing the correct breaker size would be in order, but things on that circuit may suddenly overload the breaker. So a new or additional circuit would be in order.

    So I don't think there are any books on how to recognize dangerous existing situations. I would say that would require FULLY learning how everything should be, then from experience knowing that what you are looking at is dangerous or not.

    An experienced electrician would be the best for this in my opinion.

    Then there are all sorts of other things... Main panels, subpanels, GFCI's, AFCI's, requirements for doing certain other things when replacing a main panel, grounding, etc.

    Then in my area at least, the electric company has its own set of rules called "electric service requirements". That is a book in itself!

    So again I think you would sleep better at night if you had an electrician do this and had it inspected by an electrical inspector.

    Might want to get a few estimates. It could turn out to be not so big a deal. It really depends. Also you can many times do things in stages. Have a little done now, do a bit more later, etc.

    If you want to start learning to at least do a bit of wiring on your own, here are some books...

    http://www.buildersbooksource.com/cgi-bin/booksite/22976.html

    http://www.buildersbooksource.com/cgi-bin/booksite/21244.html

    Various electric service requirements examples...
    (Find yours from your electric company's web site)
    http://www.google.com/search?hl=en&...rvice+requirements"&btnG=Search&aq=f&oq=&aqi=
     
  14. mnalep

    mnalep Member

    Joined:
    Apr 29, 2008
    Location:
    Redford, Michigan
    Well, that sounds like good advice. I will have to postpone doing anything with the fuse panel, as I can't put the money into it now. I was just hoping I could do it myself. I'm pretty handy, and do most of my own repairs around the house, and my car.

    I'm used to learning new things, but I've also made some mistakes while learning. Most of those did not keep me from sleeping well at night, although trying to plan solutions to some of those problems did keep me awake.
     
  15. Ford2001

    Ford2001 New Member

    Joined:
    Sep 11, 2009
    Occupation:
    property care taker
    Location:
    Manchester, Vermont
    Lost 7 lights replacing on light bulb on front porch

    mnalep, your thread dated 10-11-09

    Question did you get your light back up, and working?
     
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