Short circuit, now no light in two rooms

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Old 06-20-19, 07:30 AM
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Short circuit, now no light in two rooms

(Please see the attachment titled "Brief Background." It isn't essential, but it may help.)

I intend to install under-cabinet lights. A box is conveniently located. One of its three switches has never done anything since I moved in, no doubt because its circuit measures 0 volts. So, I removed it. During the process, its “top bare wire” (fig. 2; circled, fig. 1) touched metal on the garbage disposal.

BIG arc.

I reset the breaker and measured the voltage across that unintended circuit: 240 volts. (HUH??) I then put a wire nut onto both black wires that were connected to the non-functioning switch (fig. 3).

Since then, there has been no light from two kitchen track light sets (five small, 35-watt halogens each) and six various-sized spot and flood lights in dining area ceiling. Also, foyer and porch. Eight switches that currently do nothing. (Fig. 6)

I tested each kitchen and dining room switch for continuity. No problem found in 3 conventional switches. Not sure how to test the dimmers. Connections are inside. I doubt that they’re involved.

But what is??

I produced the table in fig. 5 by using a continuity tester to determine each receptacle’s circuit and, with every overhead light turned on, noting which went off when a breaker was tripped. (Previous owner didn't provide any kind of accurate list showing breaker and what it served. E.g., one breaker supposedly did "Lighting" but the fridge was on that circuit. Might the lights be on that circuit? How? Breaker is good.

I checked current between each circuit breaker and neutral. All measured close to 120 volts. (I may later use multimeter to check voltage at each receptacle, but I doubt anything will be far off 120.)

All light switches are good, circuit breakers for entire house are good, only recent breaker to trip was the one in the arc incident, every breaker is providing power to at least one device, and no other circuit has been messed with except in the box shown above. And no breaker has been tripped since the arcing.

The only thing that has gone wrong is the arcing, after which 16 light bulbs have been dark. But no breakers are tripped.

ANYway… How do I get those lights on??

(P.S. I’d never seen 240 volts on my multimeter before, so I decided to try to determine where it came from and why. (Table, fig. 4)
 
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Old 06-20-19, 10:45 AM
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Does the switch labeled "non-functioning switch" have three terminals on it (not counting the ground screw)? Usually they would be brass, brass and black.

My initial guess of what is happening is that someone installed a bootleg three-way switch circuit using the bare ground of a 2 conductor cable as a hot conductor. The reason you read 240V between this wire the other one is that you have two 120V circuits from different legs of the main panel converging in this junction box. Usually when you encounter this in a residential lighting circuit it's a screwed up three-way circuit.

What you'll need to do is identify which junction box this circuit originates from. Likely candidates are the ceiling box(es) suppling the light fixtures. This will guide the next step.

The underlying problem is that a loose connection has burned off somewhere in the circuit -- a wirenut, a switch terminal, etc. Finding it can be tedious. This is also a good opportunity to fix the three-way circuit.
 
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Old 06-26-19, 03:21 PM
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​​I was writing a reply to ibpooks, who raises some very interesting points. Then I decided to write this reply as an update to my own post. Since I posted, I have learned quite a bit about my house wiring. I wonder if this additional info supplies anything that he'll find pertinent.

1. The electrical panel had two blacks coming out of one breaker. I removed one and connected it to a new breaker (circuit 32). The only thing that has power in this circuit is the "non-functioning switch" wires (one hot black), which I connected with a wire nut.

I assume this points to this circuit for my two rooms without ceiling lights. Why would there be a circuit with nothing on it but a switch that seemed to do nothing (hence removing it and connecting the blacks)? (However, see 2.)

I now have my new under-cabinet lights hooked into this circuit. No problems.

2. There are two cables that just enter and leave the box. Let's call this the "in-and-out" circuit. Their blacks are connected. Their whites are connected. Another dead circuit with hot black. HOWEVER, IT DOESN’T SEEM TO BELONG TO ANY CIRCUIT YET STILL HAS A HOT BLACK. How do I know?

Well, I eventually had turned off and on about half of my breakers. I had a hunch and turned all off except for the disposal and dishwasher which are in the same box. In-and-out still had a hot black. I turned off the dishwasher and turned on the disposal. Still one hot black. I reversed that; still hot black. I turned ALL breakers off but then didn’t have anything to measure voltage against. (I was kind of relieved when I found zero volts between its hot black and the appliances.)

What the heck is THIS all about??

3. There are two pairs of 3-way switches in circuit 31, one in 29, and one that is in the kitchen, which is the only non-working pair. I mention this because ibpooks asked if the "non-functioning switch" was a 3way. It's not.

Augh.

I think my brother-in-law, who did some wiring in the kitchen quite a few years ago, might be interested enough to come for a visit. I know you folks will try to help me but if that doesn't happen and he's clueless, I guess I call an electrician.

However, I still haven't checked for burnt-off wire nuts or terminals in the ceiling fixtures. And I haven't removed any wire nuts in the two rooms except for the box I'm working in. Maybe I'll get lucky and find the problem when I dig deeper into all the boxes.
 

Last edited by PJmax; 06-26-19 at 06:29 PM. Reason: Removed un-needed quote section
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Old 06-30-19, 01:33 PM
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To anyone remotely interested... I have removed every switch cover and ceiling fixture cover and found NO BURNT OFF WIRE NUTS OR TERMINALS.

I haven't checked for continuity or voltage as yet because I'm not sure how I'd ever find voltage, given that there is a break in the circuit somewhere, and I'm not sure how to actually find the break in continuity.

I suppose I have exhausted this source of possible help and should probably go elsewhere.
 
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Old 06-30-19, 02:21 PM
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I have used one of these to trace an open connection to a hidden junction box.
Traced from the dead receptacle to a possible problem spot. Traced from the panel to the same spot. Cut a hole and there was a junction box with a loose wire nut.

https://www.acklandsgrainger.com/en/...g!542968814062!
 
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Old 07-13-19, 09:12 AM
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I've been really busy, just finally replying.

Could you elaborate on use?
Like, how to determine "possible problem spot"? What steps did you take?
And, "traced from panel to same spot"? You're at the panel. Then what?
I guess if I have to ask those questions, it's not for me.
But thanks for the link. I'll show my brother-in-law. Maybe he'd want to
split cost and keep it after we finish (one way or another).
 
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Old 07-13-19, 09:43 AM
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I had determined through testing that the hot wire was open. I knew which breaker it was on and turned it off. Then I attached the sender to the dead receptacle hot wire and used the sensor to follow the wire through the wall to a spot where the signal seemed to die. Then I attached the sender to the hot wire from the breaker and traced it until the signal seemed to die. It was the same spot as the first trace, so I cut a hole and found a junction box with a loose wire nut on the hot.
 
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Old 07-13-19, 10:13 AM
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Lights out in 2 rooms, no breaker tripped

My first question was too involved (so is finding the solution!). So this is a new, but related, question.

I've spent a lot of time looking for what's causing no lights in two rooms with no breaker being tripped.

So to present a clear picture of part of the mystery circuit, I've removed switch covers and fixtures (eight of which are recessed) and removed wires from terminals and nuts in all boxes (except recessed) involved in order to at least figure out what's connected to what. Surely this will help.

My attached diagram of one switch box (3 switches) makes sense (to me) except, with no current in the wires, how do I know where power enters and where power leaves the box? (Is it even important, given the nature of the problem?)

P.S. I've made similar diagrams for the 2 rooms and entry foyer and found NO discontinuity. I assume this means I don't have to pull the pots for the recessed fixtures out of the ceiling. I also assume I'm gonna hafta cut a hole or two but no clue where.

P.P.S. Is there a hidden GFCI that's tripped? (This burned me once 3 years ago in another house--found just before deciding where to cut drywall first. Inside Jacuzzi frame.)(Yes, I did it.) No "hidden" GFCI that I've seen. I've gone over every square inch of wall, as well as ceiling and even floor. No GFCI except for the 2 bathrooms and kitchen. Never tripped. OH how I wish I'd find one.

P.P.P.S. All breakers show 120v between terminal and neutral bar. None tripped.
 
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Old 07-13-19, 11:05 AM
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Did you identify everything on the problem circuit ?

You need to make a list. Write down everything that is working and not working on that circuit.
Circuits start at the panel and work away from the panel.
Look at your list..... plot a wiring course based on what is working and what is not.

The problem will be at the last working device or the first dead one.

It doesn't make a difference which wire is power in and power out if both are dead. If you don't have power in a switchbox.... the problem is before there.
 
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Old 07-14-19, 12:20 PM
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Thank you, joed! Heck, now that tool seems not so complicated. I gotta get my bro-in-law to come over. He did quite a bit of wiring before I moved in but most of it was over 5 years ago, so he may remember nothing even when he sees the sitch. If he's stumped (and over the phone, as I described it, he said, "I don't know" and "I'd have to see it" several times), he and I will discuss your tool idea, joed.
 
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Old 07-14-19, 02:31 PM
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PJmax--Because previous owner didn't bother to provide accurate circuit info (but neither did I, after moving in 5 years ago), I have no clue which circuit(s) the dozen light fixtures and 2 receptacles are on. I assume all on one circuit because I hate to think there are TWO circuits that have no clear home in the panel.

What I just said is, "No breaker has tripped, each shows 120v to neutral bar, yet I have a dozen non-working devices."

So NOTHING on this/these circuit(s) work(s).

There was one circuit where TWO black wires were using the same breaker (for the microwave). I bought new breaker and reassigned that wire. As it happens, the ONLY thing that "went out" when I tripped the new breaker was my NEW under-shelf lights, which replaced a switch that apparently did nothing yet did have hot coming in.

I therefore can imagine the problem stems from the old/new switch. But it's more complicated than this. Refer to my original post. The wiring in this house is wacko. I don't have the expertise to just go fix this. But I'm whacking away at it, learning a LOT.

Attached are my "lists" of things that don't work. I almost have every wire's beginning and end. But NONE of the unidentified loose wire ends are continuous to any breaker. So no clue what the actual power source is (should be). I'm not positive that every diagram is correct. If there are two loose ends in a box, one is IN and one is OUT. A couple are easy to decide. A couple aren't. So there are question marks on a few/most diagrams.

I just re-read PJmax's post. I can EASILY imagine that the problem occurs where my new switch (the replaced old does-nothing switch) is located. The hot wire to both old and new switches touched garbage disposal terminal and made a BIG arc. Then... no lights. Big arc = 240 volts between hot wire to switch and GD terminal. Other wire that was attached to the non-functioning switch carries no current. I've nutted it to the other half that powers my new light by a stub to one of the terminals..

As it stands, the "last working device" is the last in this circuit (see FOYER). The first non-working device is impossible to determine without a list of items on the circuit. It could well be a hidden device, maybe a tripped GFCI, maybe a work box with burnt off nut.

I hope my "lists" help someone help me out. I'm retired, so what else do I have to do, but I don't see any hope of success. I refuse to call an electrician after all the work I've done!! I may eventually HAVE to. (BTW, we DO have light in both rooms, just no ceiling lights.) But it'd be great if, with some guidance, I could do it myself, with credit to others!!
 
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