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  • Backfeed... sources and solutions

    Ok... As mentioned in an earlier thread I rewired my entire home. It was mostly knob and tube but is now all clean 12-2 and 12-3

    I thuroughly checked all the new circuits I put in. Only ran into one system that had backfeed. The bathroom had been redone before I moved into my home. It was wired with new romex and tied into the old Knob and tube. So I simply tied the romex into a homerun that I dragged up into the attic and terminated and eventually turned off the knob and tube circuit.

    This system has backfeed in it and I can't figure out whats going on. It has a light, a fan, and an outlet on it. The power goes down into the 2 wide gangbox that has the switched for the light and fan. There is then 3 wires that come out of the gangbox. The 2 switched lines and the single outlet line which ties directly into the source comming down. I have tried everything and cant seem to find a short anywhere.

    Could you guys give me a few possibilities as to what causes backfeed in a system. What should I check out? I know it reflects badly on me that my house has a ciruit with some backfeed but this one wasnt my fault. I just tied the power in. I did check to make sure there isnt anything else tying in in the walls too.

    Thanks,

    Josh

  • #2
    Josh,

    Your problem intrigues me but am having a hard time grasping the setup from the description. Can you post a drawing or schematic so I can visualize it better?

    Jerry
    It is impossible to make anything foolproof because fools are so ingenious.

    Comment


    • #3
      Originally posted by Josh
      This system has back feed in it and I can't figure out whats going on. It has a light, a fan, and an outlet on it. The power goes down into the 2 wide gang box that has the switched for the light and fan. There is then 3 wires that come out of the gang box. The 2 switched lines and the single outlet line which ties directly into the source coming down. I have tried everything and cant seem to find a short anywhere.
      I'm not sure if i have this right......

      The power goes into you 2 gange box with your black white and bare wire, the provide power to your light and fan with the black white and bare going to each. are any of the wire touching the connections on your switch's? Turn off the circuit and wrap the back of the switch's with electrical tape. you then have your black white and bare head to your outlet from that box or is it a different Circuit. make sure your ground wire is not touching one of the other connections tap over all the screws on the back of your outlet. If none of that works and you are still having a short then you may have a staple that was to tight or a nail going through the wire. Hopefully you are able to get the wires. If you romex didn't run in the middle of the stud then you need to get a nailpalte to protect the wire where it is closer than 1 1/4 inchs to edge
      Last edited by Polar Sparky 1224; 02-05-2006, 10:54 PM.
      "Diplomacy is saying nice dodging until you can find a rock." Will Rogers
      "If a Monkey can do your job, are you in the right profession?

      Comment


      • #4
        My biggest fear now is the staple problem. I will take my gang box apart and tape everything in there although I dont think that was the issue. Its a good idea though since is crowded in there. I did find the source of backfeed in a circuit that I put in once. I overtightened one of the 3/4 inch clamps that went into the box which charged the entire box. so when the ground would touch the box the breaker would throw that was early in my experience though. Was extra careful with everyting I did after that. The issue with this last problem in the house is that someone else did it and I cant check every inche of the romex for anything they did wrong.

        Thanks for the ideas though. I will tape up all the contacts just to rule that out then maybe run my own power down to that box if I can drop it through the wall cavity.

        Thanks,

        Josh

        Comment


        • #5
          it may be a hassle but take out your switch's and turn the power back on and see if one is hot. Hopefully you have a voltage tester.... Then turn the power off again and put one switch back in and turn on the device connected to that switch. Connect the other switch and turn it on. Then do the outlet and hopefully you can find the problem.
          "Diplomacy is saying nice dodging until you can find a rock." Will Rogers
          "If a Monkey can do your job, are you in the right profession?

          Comment


          • #6
            GFI's

            Just to let you know you might want to check your GFI's Plugs just to make sure they are ok! From tome to time they will go bad or even get a bad one out of the box and they can back feed... been there done that! Just to give you a little back ground I am an electrician or at least that is what i keep telling my self... I have been in the buisness for my entire life and i grew up in a family of electricians. I am only 26 but i have been around the block a time or two when it comes to electricity. I am not a master at residential but i know my stuff when it comes to commercial and industrial. I have wored in all the fields and have passed my masters!!!

            Comment


            • #7
              I replaced the GFI a couple weeks ago but havent torn the circuit apart to test it for backfeed yet. I will try and get to it this weekend. Its amazing how busy I can get durring the winter. And I thought summer was the busy season... (maybe thats because I always end up loosing my weekends to golf )

              Thanks a ton for the advice. I will try it all and give you guys an update after the problem is gone.

              Thanks,

              josh

              Comment


              • #8
                Backfeed in circuit

                Hi Josh,
                Just a thought for your problem. Have you checked continuity in the bathroom fan itself? If the fan has an insulation breakdown in its wiring (could be armature), you could be getting some backfeed less than 120 volts leaking through on the NEUTRAL wire. You might want to check for that with your voltmeter. I was working on a light circuit not long ago and got just a "blip" "blip" signal on my tick tracer. Since the switch was off, I thought I was safe. Was getting backfeed on neutral wire from an adjacent light fixture which registered 92.5 volts when I tested it. Unfortunately, I didn't get around to testing it until I had encountered all 92 volts running from my left hand out to my right hand. Made for an uncomfortable lesson, but one that punctuated the need to work on circuits that are totally cold. Hope this helps. Jim.

                Comment


                • #9
                  Josh,
                  Most people unfamiliar with Knob & Tube wiring, do not realize that the wiring method is very, very different from todays wiring methods. The main difference is the switch box wiring does not contain any "hot" wires. The wiring in the switch device box is actually the neutrals being used as the switch legs. Typically, the "hot" feed is in the fan or light fixture box in the ceiling and always feeds power to the fixture, thus, the neutral leg is fully completed when the switch is turned on, the circuit is made, and the fixture lights. The odd voltage you are reading is the "hot" return or "backfeed" voltage coming through the fan motor windings or light bulb (always between 50 and 100 volts depending on the windings or the filiment resistance) looking for that neutral wire at the line side of the switch. I hope this helps. As always, excersize proper PPE and precautions when working with live power. More people suffer from low voltage hazards than you can imagine. OSHA reports 3000+ electrical related hospital visits per year.
                  Perry, Cincinnati, OH, Master Electrician

                  Comment


                  • #10
                    HERE'S AN IDEA

                    HIRE A LICENSED ELECTRICIAN
                    PROBLEM SOLVED !!!!!!!

                    Comment


                    • #11
                      --------------------------------------------------------------------------------

                      MD MASTER SPARKY

                      you better lighten up some or you will become a master #!*%$@?*#
                      Charlie

                      My seek the peek fundraiser page
                      http://observatory.mountwashington.o...nal&fr_id=1040


                      http://www.mountwashington.org/weather/conditions.php

                      new work pictures 12/09
                      http://public.fotki.com/hvachawk/

                      Comment


                      • #12
                        Originally posted by MD MASTER SPARKY
                        HERE'S AN IDEA

                        HIRE A LICENSED HIT MAN TO TAKE OUT A LOCAL ELECTRICIAN
                        PROBLEM SOLVED !!!!!!!
                        Now that's not very nice aren't we here to answer questions rather that imply that others shouldn't try and do things for themselves? If you know so much then share with us!!!

                        Shared knowledge = shared safety!!!

                        Am I right or am I right or do you need a third option? just play nice.....
                        "Diplomacy is saying nice dodging until you can find a rock." Will Rogers
                        "If a Monkey can do your job, are you in the right profession?

                        Comment


                        • #13
                          Yeah I need to have my uncle stop by some weekend and solve it with me. Its annoying checking the same things over and over and not finidng the problem.

                          Josh

                          Comment


                          • #14
                            just a thought

                            Originally posted by Josh
                            Ok... As mentioned in an earlier thread I rewired my entire home. It was mostly knob and tube but is now all clean 12-2 and 12-3

                            I thuroughly checked all the new circuits I put in. Only ran into one system that had backfeed. The bathroom had been redone before I moved into my home. It was wired with new romex and tied into the old Knob and tube. So I simply tied the romex into a homerun that I dragged up into the attic and terminated and eventually turned off the knob and tube circuit.

                            This system has backfeed in it and I can't figure out whats going on. It has a light, a fan, and an outlet on it. The power goes down into the 2 wide gangbox that has the switched for the light and fan. There is then 3 wires that come out of the gangbox. The 2 switched lines and the single outlet line which ties directly into the source comming down. I have tried everything and cant seem to find a short anywhere.

                            Could you guys give me a few possibilities as to what causes backfeed in a system. What should I check out? I know it reflects badly on me that my house has a ciruit with some backfeed but this one wasnt my fault. I just tied the power in. I did check to make sure there isnt anything else tying in in the walls too.

                            Thanks,

                            Josh
                            in knob and tube switching its the neutrals that is being switched

                            Comment

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