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  • Troubleshooting dead electrical circuit

    I could do with some help trying to figure this one out. A few days ago a circuit stopped working at my home. I don't recall anything specific happening prior to this event like an overload. I first noticed a dead outdoor electrical outlet when trying to run some garden tools. Later that night a noticed a couple of lights indoors (wired to the same switch) not working.

    I did some further testing and figured out that these 2 lights and a bunch of electrical outlets are dead. I started by checking the breaker panel. Nothing was tripped. However, I then manually tripped and reset each of the breakers. Still nothing.

    I then used a multimeter and measured the voltage on the output screw of each breaker. All of them read 120V. I also made sure each screw was on tight and the wires were firm in the breaker.

    I did come across a GFCI outlet on one of the downstairs bathrooms which was also dead and the black switch seemed to have frozen into place as I was unable to depress. On the off chance this was the faulty part I removed it but then I could not detect voltage on any of the wires. Plus I presume they will not use a GFCI on the lights would they?

    One other thing I did was to use the audio voltage tester and from what I could see all the hot wires leaving the breakers were live.

    So I'm not sure how to continue troubleshooting this. Could a wire connector come apart somewhere.

    Any suggestions as to what the cause might be?

  • #2
    Re: Troubleshooting dead electrical circuit

    The previous owner of my home was a DIYer and not too good at it. I've had a few identical problems to the one you're reporting.

    In my case, a wire in an upstream switch box came out of the wire nut. I've found that the vast majority of problems happen in a box. Those that don't seem to mostly be collateral damage when someone penetrates a wall or ceiling. So if there has been some wall penetrating, such as picture hanging or such, that could be a place to start. But lacking that, I bet you'll find the problem in an upstream box. It's nice to have diagrams that show every box on a given breaker, but most folks don't have that. I write the breaker number on the inside of the switch plate. For junction boxes in the attic, I write the breaker number on the outside of the cover. It saves a little time.

    In one case where I had a wire come out of the wirenut, the wire shorted. It burned about three feet up the stud in the wall until it finally broke continuity. The breaker didn't trip. Coulda been ugly.

    The breaker panel was a Zinnsco. It's in a landfill somewhere now.

    Comment


    • #3
      Re: Troubleshooting dead electrical circuit

      Thanks Andy - sounds like I will need to open up all the boxes and switches to investigate further. In my case though I have been the longest owner of the house (about 10 years). The house is 13 years old and as far as I knew the first two owners were not much into DIY and did not modify the original design. I'm the only one who has added new circuits (about 3 including an outdoor circuit for my backyard) but as far as I know the ones I added have been working fine. Could have been something to do with the quality of the electrical contractors the homebuilders used I suppose. No excuse for a wirenut coming off like that.

      Comment


      • #4
        Re: Troubleshooting dead electrical circuit

        It does sound like wires have come apart in a box. Also in Illinois the inspectors will make any fixture that a person can touch water and a switch or light must run off the load side of the GFCI. Exterior lights also.
        Can lights above toilets. can lights above tubs or showers and sinks.

        I did one large bathroom and all the lights had to run through the GFCI so when it tripped at night it was dark now try to find your way out.

        Hope this helps

        Comment


        • #5
          Re: Troubleshooting dead electrical circuit

          OK Blue,
          Let's walk you thru a couple things here. What kind of panel/breakers do you have. If it's a Federal Pacific, they're known for lots of problems all by themselves. If it is something else, even a Square D or Cutler Hammer, the breakers can/will wear out after awhile. The non-contact (audio) tester you mentioned usually is NOT the best way to test inside a panel because the magnetics from adjacent hot wires will indicate that there is power on a circuit when there is not. Use a Wiggy or use your volt meter to be sure there is current from the breaker on out. Did your DIY predecessor pigtail the receptacles inside the boxes (downstream) or did he use the cheapo backstab method. May have had a wire come loose on a backstab. Pigtail is the way to go on these. Also, some don't know how to use a wire nut and will just place the wires next to each other and then give a little twist or two. Use linesmans, twist the two together, then put nut on top. Guaranteed, they will never ever come apart. I've seen more than a few circuits that failed one day because a wire fell out of a wire nut connection. To find it, you're going to have to disassemble every non-working receptacle and check the connections individually until you get to the break. There are test sets to use to locate, but they are a bit pricey for your one time use, so a search via each recept. is going to be the way to go. I'm also suspicious of that tripped GFCI that won't reset. Turn your power off and replace that one if it won't reset. Do you have any of the outlets switched? Bad switch can cause problems too. And don't forget, if the DIYer used cheapo recepts, they do wear out. When I find these I tell the homeowner that eventually, they will end up replacing just about all of them in time. I put in Spec Grade recepts because they stand up better and longer. Same with Spec Grade switches. If you do all these and haven't found, then you're going to have to test for continuity in between outlets with your meter. You need power switched off for these tests or you will burn your meter up. And while you could check for those loose connections mentioned at first with power on, unless you really really know what you are doing, you need to power down that circuit because we want you to continue posting here and not become a statistic. While some people may try to tell you you have nothing to fear from a 120 volt shock, it is the amps (actually milliamps in the case of heart stoppage), that kills, not the volts, and the amperage from a 120 volt line will accomplish that in short order. So do not make that mistake. If you go thru all these steps and you still don't have an answer, post back again, and we'll try to look at plan B.
          Cheers,
          Jim Don

          Comment


          • #6
            Re: Troubleshooting dead electrical circuit

            I've tried three times to answer this question, but everytime, it says a moderator must approve the answer. What gives? This is extremely frustrating.
            Jim

            Comment


            • #7
              Re: Troubleshooting dead electrical circuit

              OK Blue,
              Let's walk you thru a couple things here. What kind of panel/breakers do you have. If it's a Federal Pacific, they're known for lots of problems all by themselves. If it is something else, even a Square D or Cutler Hammer, the breakers can/will wear out after awhile. The non-contact (audio) tester you mentioned usually is NOT the best way to test inside a panel because the magnetics from adjacent hot wires will indicate that there is power on a circuit when there is not. Use a Wiggy or use your volt meter to be sure there is current from the breaker on out.

              Comment


              • #8
                Re: Troubleshooting dead electrical circuit

                Did your DIY predecessor pigtail the receptacles inside the boxes (downstream) or did he use the cheapo backstab method. May have had a wire come loose on a backstab. Pigtail is the way to go on these. Also, some don't know how to use a wire nut and will just place the wires next to each other and then give a little twist or two. Use linesmans, twist the two together, then put nut on top. Guaranteed, they will never ever come apart. I've seen more than a few circuits that failed one day because a wire fell out of a wire nut connection. To find it, you're going to have to disassemble every non-working receptacle and check the connections individually until you get to the break. There are test sets to use to locate, but they are a bit pricey for your one time use, so a search via each recept. is going to be the way to go. I'm also suspicious of that tripped GFCI that won't reset. Turn your power off and replace that one if it won't reset. Do you have any of the outlets switched? Bad switch can cause problems too. And don't forget, if the DIYer used cheapo recepts, they do wear out. When I find these I tell the homeowner that eventually, they will end up replacing just about all of them in time. I put in Spec Grade recepts because they stand up better and longer. Same with Spec Grade switches. If you do all these and haven't found, then you're going to have to test for continuity in between outlets with your meter. You need power switched off for these tests or you will burn your meter up. And while you could check for those loose connections mentioned at first with power on, unless you really really know what you are doing, you need to power down that circuit because we want you to continue posting here and not become a statistic.

                Comment


                • #9
                  Re: Troubleshooting dead electrical circuit

                  While some people may try to tell you you have nothing to fear from a 120 volt shock, it is the amps (actually milliamps in the case of heart stoppage), that kills, not the volts, and the amperage from a 120 volt line will accomplish that in short order. So do not make that mistake. If you go thru all these steps and you still don't have an answer, post back again, and we'll try to look at plan B.
                  Cheers,
                  Jim Don

                  Comment


                  • #10
                    Re: Troubleshooting dead electrical circuit

                    wow, what an exercise in futility!!!

                    BTW Blue. Hope this helped. The three individual posts are just a breakout of the one I first wrote.
                    Cheers,
                    Jim Don

                    Comment


                    • #11
                      Re: Troubleshooting dead electrical circuit

                      Hi Jim - thanks for the detailed (multiple) posts. Glad you got through .

                      To go over what you posted - firstly I do not believe there was a DIYer involved with any work on the house prior to me purchasing it. And as far as the audio tester - yes I know they are not reliable but I could not find an easy way to verify that the outgoing wires from the breakers were carrying current. However, as I posted I tested the output of each breaker with my multimeter and read 120V (at the screw terminal).

                      No idea about the brand of the breaker - I will check.

                      I guess the only way as you say is to open up each box and investigate. The couple of lights that are not working are recessed. I assume there are potentially wirenuts inside the fixture. How do I access those?

                      As far as continuity tests between outlets - good idea but in many cases the distance between the outlets is too long for my probes. Do they sell very long probes for doing this kind of testing.

                      Comment


                      • #12
                        Re: Troubleshooting dead electrical circuit

                        I agree with all posts here. In addition,if you have both lights and recepts on the same circuit, you may have a connection problem in light boxes as well.

                        Huck

                        Can lights can be accessed either in the attick or from inside the can itself. Best to do it from attick if you have access to them.If not then remove the bulb and trim from housing. Their should be 3 screws on the inside walls of the housing, remove them and lift the can up into attick to gain access to the j-box on the can light fixture
                        Last edited by huckster4; 01-17-2011, 12:09 AM.

                        Comment


                        • #13
                          Re: Troubleshooting dead electrical circuit

                          Just use an extension cord, even a light duty lamp cord, to extend the reach of the probes for your volt/ohm meter. Couple of jumpers made up with alligator clips will do the connections for ya.
                          Jim

                          Comment


                          • #14
                            Re: Troubleshooting dead electrical circuit

                            Originally posted by huckster4 View Post
                            I agree with all posts here. In addition,if you have both lights and recepts on the same circuit, you may have a connection problem in light boxes as well.

                            Huck
                            Yes good point and as I mentioned in the previous post it's a recessed light fixture. How do I gain access to the connectors in the recessed fixture?

                            Comment


                            • #15
                              Re: Troubleshooting dead electrical circuit

                              I edited my last post with instructions. sorry, your quick!

                              Comment

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