Advice for troubleshooting a bad circuit

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Old 10-11-09, 04:56 PM
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Advice for troubleshooting a bad circuit

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
 
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Old 10-11-09, 05:06 PM
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Do you have any GFCIs anywhere? It could be a bathroom or kitchen or garage or basement or an outside receptacle. It could also be one hidden behind furniture you have forgotten about. When you have ruled out there is a tripped GFCI then check the last working receptacle or light on the circuit and then the first non working. Also check any wire nuts including in switch boxes. Move any backstabbed wires to the screws
 
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Old 10-11-09, 08:15 PM
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I'm sure there is no GFCI. The circuit is in a home built around 1930.

I don't know how to test for the last working receptacle and the first non-working one?

I'm pretty sure all switch wires are screwed on (not backstabbed), but I will double check.
 
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Old 10-11-09, 08:28 PM
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I don't know how to test for the last working receptacle and the first non-working one
That is guess in an old house. You find the working receptacle or light on the circuit nearest the first non working and check all of the connections and then check all the connections in the nearest non-working. In many cases the installation is in a row starting at the fuse box and working out. In a house that old though you may have to check the connections in every device supplied by the fuse both working and non working. There could also be Jboxes, hopefully not buried in a wall, with no device just wires going in and out.
 
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Old 10-12-09, 07:12 AM
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matt,

Did all you realize at the time you replaced the porch socket was that only the porch was affected? Or aren't you sure about this, in retrospect? Could the circuit have been bad and you did not know that, and presumed since no power there, and say replacing the bulb did not help, that the socket was bad?

If it was just the porch bulb socket that was screwed up, and after you replaced it, all those other lights failed to work, I'd suspect that the box above the light is a jbox location, and one of the say 3 or 4 wires in a wire nut came loose from the rest. I have had to find such problems and correct that very scenario on occasions already.

Them causes are hard to find, often when boxes are jammed with wires, and no one wire is actually outside the wire nut. Only loose in the wire nut. In such cases you turn on the light and do the wire wiggling test and see if the light flickers on and off. Basement jboxes above those typical open basemnt lights can be a location also. I had a loose one in there about 3 years ago.
 
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Old 10-12-09, 07:45 AM
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Wire

Did you correct the bare wire problem in the ceiling box?
 
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Old 10-12-09, 08:05 AM
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ecman51,

I know the other lights were working (bathroom, bedroom, etc,) while porch was out.

The switches controlling the porch and family room are in one outlet. One black wire is screwed onto the bottom screw of switch one, using a bare spot on the black wire, then this wire continues (insulated) to the bottom of switch 2 screw in. There is one black wire, screwed in at the top of each switch, going I assume, to each light. The 3 white wires are twisted together in only electrical tape (gobs of it), and no wire nut.
 
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Old 10-12-09, 08:09 AM
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ray2047,

Is there an 'easy' way to find if anything is working on that circuit. I suppose I could pull out all receptacle switches, pull out all fuses except for the suspicious circuit, and see if any receptacles had power to them. I assume I'd leave the plug outlets in the wall, and just probe them to test.
 
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Old 10-12-09, 08:14 AM
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wire, I plan on doing that. I have pulled the porch light fixture off. I was first going to insure power at the particular fuses service panel, and a good fuse. Then I was going to disconnect porch light wiring from circuit (it's switch), and see if that get's me power back to interior lights. Right now, the interior lights are my first need to get working again. If the fuse and panel work ok, and disconnecting the porch light wiring does not give me power back - I assume I have another fault in this circuit? Question is, am I right, and how do I find it?
 
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Old 10-12-09, 08:30 AM
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You know all that is on the circuit. Or do you? Do you realize that you could have one good outlet or light somewhere, that still works, yet everything downstream of it does not work(due to the right loose wire)? Not that this is your case, but could be.

You need to shut off other breakers that are in that area of the house to make sure that their lights and outlets go out. If not, that means they are on your bad circuit. In the case of an outlet you did not realize was on that bad circuit, it have to be an outlet that has 4 wires hooked to it, not just two.

Since you do not know where the circuit starts or end, this search and destroy mission will simply take time, to find the problem. But sometimes with certain layouts you can at least reasonably guess as to what might be the start or end of the circuit, so you pick each of those 2 ends to investigate first.
 
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Old 10-12-09, 02:29 PM
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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?
 
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Old 10-12-09, 04:13 PM
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I worked on this old house that had an inline socket up at the basement ceiling, with a 15 amp fuse in it. I've gone through my entire life always saying to myself, "Huh!' I've said that a lot.
 
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