Help! Half of my circuit works, half doesn't.

Today half of one of my home's circuits stopped working. At first I thought it was the breaker, so I put a new one in. It was then I realized that some of the items on that circuit were working, and others were not. I did have some workers operating some heavy tools at my house, initially I thought that the circuit was overloaded(?), or something burned out (is that possible?)... I can't figure what it might be, but my new line of thinking is that the vibrations of the equipment they were using shook loose a connection somewhere... any ideas on how to trace this problem out?? Any help would be so appreciated.

 

What is on the CKt? Lighting, receptacles , or a combo of both. If You already know everything that is on the ckt, then a simple 2wire electrical tester and some patience will do you just fine.

Basic rule of thumb is you have a problem at either the first location that doesnt work, or the Last one that does.
My guess is if you had machinery operating , the excess current draw overheated a connection, and here you are.

 

Thanks for the info... it is a combo of lights and receps... what would I be looking for? Something burned? Or something loose?

 

Burned or loose, either is possible. I would be inclined to feel that it would probably be at an outlet that has been installed by "BACKSTAB". While you are checking, remove the "PUSH-INS", and move them to the screws and tighten down.

 

Is it half of your circuits work and half do not or that half of a single circuit does not work?

For half of your circuits, shut everything off and call the power company.

For half of a circuit, look for an open on the circuit. A location where a wire has become disconnected.

 

It's a failed backstab. Search this forum for "backstab".

 

Thanks so much for the suggestions... I found the problem, it was a loose wire nut in a junction box in my attic.

 

I've got a similar issue that I've been troubleshooting, but can't figure out yet. How did you actually find the problem?

 

There's usually no magic way to find the failure other than an exhaustive search. Be sure to look in both working and non-working outlets.

I always recommend one of those outlet testers, something that has three lamps and plugs into a receptacle. It can tell you what you're looking for and help narrow the search.

Note that it is rare to have a junction box that is only accessible from the attic.

If you tell us where you live, in what year the house was built, and in what room(s) you are having the problem, we can usually suggest more likely things to check.

 

I have one of those testers, and all the effected outlets show a hot/ground reversal. Which based on the info available on this site really indicates a open neutral.

How could it be in an outlet that is still working?? Could it be in a light switch box also?

I live in the northern virginia area, it's a relatively new house, 7 yrs old. Almost all of the outlets use backstab connections, but all the ones I've checked seem to be still well connected. I'm having the problem with most, but not all, outlets in my daughters bedroom and the room directly beneath her room, which is the dining room. It is also effecting the ceiling lights in those rooms. I have noticed that if I turn on a ceiling fan light switch in her bedroom that the symptoms change on the indicator lamp. With the switch off the outlets show open neutral, with the switch on they show hot/gnd reversal.

This led me to suspect the ceiling fan wiring, and it was installed fairly recently, in early summer this year. So I thought maybe vibration from the ceiling fan caused the neutral wires to open. But when I pulled it open I didn't see anything wrong with it.

Thanks for the help

 

Yes, you have an open neutral. It can be at a receptacle still working if it is the OUTGOING neutral wire that is open (disconnected).

The most likely suspect is a failed back stab connection. Open each box on the circuit (including those that work, as we have just discussed) and check all connections. Move any back stabbed connections to the screw terminals and remake any wire nutted connections with new wire nuts.

Yes, it could be at a light switch, but it is less likely to be so. It would be a neutral splice in the box that has failed.

 

you say you were fine until the workers were using the electric.

go to where they were using the outlet and smell the recepticle.

loose wires in stab locks will arc and a lot of times you can actually smell this through the outlet/cover. Open that recepticle up and check the wires.


A little food for thought.
the way most electricians will wire residential homes, is start the beginning of the branch circuit at the outlet that is closest to the electrical panel for the home run(branch circuit feeders).

Then they will work around the room feeding into the next box then out of that box,going to the next and so on, stopping at no more then 12 outlets for one branch circuit. An outlet is any device, switch, recept., or ceiling light. The last recepticle outlet of a branch circuit will only have two insulated wires in the box.

Most feeds for newer home's ceiling fixtures, go through the switch and leg the ceiling fixture. Older homes might pull the feeds to the ceiling fixture then drop just a switch leg down from there into the switch box.

If the switch box only has 2 insulated wires in it.. it is a switch leg and carries no neutral, so you'd have to look up in the ceiling box for a lost neutral.

Newer home also don't use ceiling fixtures in every room like older homes did. The switches in rooms with no ceiling lighting go into the recepticle to control table lamps. these switch boxes are mostly switch legs that carry no neutral.

So how does this help in troubleshooting?? If you turn the breaker off then test the circuit outlets for power, you can usually see the closest outlet to the panel(branch circuit feed), and the last outlet in the circuit.

From here you can split the circuit in half, and remove that cover and device and check for the neutral being off and power. If all is well there go half way between there and the end of the circuit and check there the same way. If no power there it's between there and the first one you removed.

The other thing is once you figured out where the circuit starts and stops with the power off you turn the power back on and find the last working outlet. then open it up and check the feed out wires to make sure they are secure if they are go the next device inline and see if the feed in wires are secure.

Hope this helps

 

I finally found the problem!!

It took me long enough! I had opened up every outlet and moved the backstab neutral connections to screws, which by the way is a realy pain in the @$$, since most of those connects are 1/2" or deeper in the holes and not easy to pull out. But still the problem persisted. I pulled all the switch plates off to check the wirenuts on spliced neutrals - no luck.

Tonight I went back to a couple outlets where there were neutrals connected via backstab AND to the screws on the same side/terminal. I checked those backstabs to ensure they were tight but while doing so noticed one of the screw connects seemed to have a little insulation under the screw. I started to back the screw out and noticed that it wasn't very tight, I pulled the wire out rebent it around the screw and tightened the screw down on it, flipped the breaker and voila...everything was working! So I guess they were using both connections on the outlet like a wirenut, to run multiple returns? And one of them had a little insulation on the wire under the screw, so once I got a good connection and tightened the screw it resovled the problem.

Thanks to everyone for the input and advice, it gave me the understanding and help I needed to find the problem.


Cheers

 

when you see two blacks on brass and two whites on silver on a recepticle, it is usually what is refered to as feeders in feeders out.
If you see more then two pair of wires attached in the same manor it could be that they brought the home run or feed in into that box, then went two different direction from there on the feeders out to wire the rest of the branch circuit.

yes the screws and tab locks are interconnected for the hot (brass) side and neutral (silver/white) side of the recepticle, so it is like a wire nut connection.

there is only one return going back to the panel, but in parallel wiring all neutral (white wires)tie together, and all hots (black wires) tie together, then the recepticles connect between the two sides.