(Solved) House Electrical Problem, I'm Stumped

[John Kloehr]

First time I've been stumped in decades. Only experienced electricians need read beyond this point.

 

Was vacuuming out rats nests out of the cars outside, house breaker for that circuit blew.

Reset breaker, finished job. Turned shop vacuum off.

 

A few minutes later, breaker blew again.

 

Tried to reset breaker, instant pop.

 

Unplugged (I thought)  all lamps and such on the circuit (kitty heated bed too). Still an instant pop.

 

Verify power is off, check with ohm meter. 12 ohms from hot to neutral on this circuit... That would be 10amps draw. Find one more lamp plugged in (old-style filament bulb, resistance drops as they heat up, but should not blow breaker). Unplug that. Resistance to neutral (and to ground) is now 0.38 megohm (380,000 ohms). Also found a UPS was activated, one more plug, unplugged that and a lamp (off) too. Also unplugged neon lamp in a bathroom.

 

Breaker still pops instantly.

 

Bad breaker? Disconnect the wire from that breaker and another circuit, try the suspect wire on the alternate breaker. Pops instantly. Also verified neutral is bonded to ground at the  panel.

 

So, not a bad breaker, no short circuit, but acts like a short circuit. It is not a GFCI or arc fault breaker, just an old school breaker that will trip on too many amps. But the ohmmeter shows no short.

 

Thoughts? Ohm meter reading says the circuit should draw less than a milliamp, breaker blows like a dead short. And yes, there are rats, but if they chewed wires and they were touching, I would see the short on the ohm meter.

[Tennessee williams]

Well. That IS weird. Sure there's no gfci outlet snuck in that circuit?

[Cholla]

Regular ohm meters don't always show a short/ground and they are usually powered by a 9 volt battery or less. Use a megohm meter. The units I use generate about 1000 volts dc which can show a breakdown in insulation while a regular meter will not.

 

[John Kloehr]

There are three GFCI outlets on the circuit that I have found. But Google chi did not find any evidence of GFCI outlets blowing breakers. The (2-prong) neon lamp was plugged into one of them.

 

I have plenty of instances of bad GFCI outlets not working/tripping and also killing downstream outlets, but never an instance of a bad GFCI blowing a panel breaker.

[John Kloehr]

4 minutes ago, Cholla said:

Regular ohm meters don't always show a short/ground and they are usually powered by a 9 volt battery or less. Use a megohm meter. The units I use generate about 1000 volts dc which can show a breakdown in insulation while a regular meter will not.

 

Hmmm... Hi Pot test for an arc? Back in a minute with an edit.

 

On edit: At 120V, I can't see a sustained arc, at 220V it seems to be possible. Will sleep on that but it would require two circuits on opposite legs to get close enough to each other to create an arc. Then assuming one breaker is quicker than the other, that one would trip.

[Cholla]

4 minutes ago, John Kloehr said:

There are three GFCI outlets on the circuit that I have found. But Google chi did not find any evidence of GFCI outlets blowing breakers. The (2-prong) neon lamp was plugged into one of them.

 

I have plenty of instances of bad GFCI outlets not working/tripping and also killing downstream outlets, but never an instance of a bad GFCI blowing a panel breaker.

Don't use the megger on a wire still attached to the breaker in the panel.

 

I have had GFCI receptacles blow circuit breakers. The best thing to do is start breaking the circuit down until the breaker trips stops. Pull the GFCI receptacle out and isolate the wires. See if the tripping stops.

[John Kloehr]

15 minutes ago, Cholla said:

Don't use the megger on a wire still attached to the breaker in the panel.

 

I have had GFCI receptacles blow circuit breakers. The best thing to do is start breaking the circuit down until the breaker trips stops. Pull the GFCI receptacle out and isolate the wires. See if the tripping stops.

Breaker off, wire removed from breaker, confirmed no voltage on wire prior to testing ohms.

 

I'll pull the wires off the GFCIs tomorrow and update then. Still open to other ideas, never had a popping breaker like this in the past without a dead short in the house wiring.

[Sedalia Dave]

Time to break down the circuit and begin isolating it. Can you access the attic so that you can physically map how the wiring goes from outlet to outlet?

 

If you have a circuit hound it is a lot easier.

[Pat Riot]

I had a faulty GFCI give me fits years ago in the same scenario. Problem was that GFCI shouldn’t have been in the circuit it was affecting so I passed it by during troubleshooting. I am pretty sure a drunk wired that particular house. 

[Tennessee williams]

1 hour ago, John Kloehr said:

There are three GFCI outlets on the circuit that I have found. But Google chi did not find any evidence of GFCI outlets blowing breakers. The (2-prong) neon lamp was plugged into one of them.

 

I have plenty of instances of bad GFCI outlets not working/tripping and also killing downstream outlets, but never an instance of a bad GFCI blowing a panel breaker.

They can do it. Had a beaker a few months ago kept tripping. Stopped after replacing the bad gfci. It looked like it had gotten hot...

[Abilene Slim SASS 81783]

Pull the covers and visually inspect all the outlets & connections on that circuit. Then pull the panel cover and visually inspect the breaker connections. 
 

Sometimes you find fried connection that shorts intermittently. I’ve found those at an outlet and a breaker. 
 

 

[Dirty Dan Dawkins]

Sounds like a ground fault of some sort. Read for continuity from hot to ground. This will read through the ground to neutral bond at the main disconnect in the event there is a ground to neutral fault. You have to determine if it’s a ground fault or ground to neutral fault. If you turn the breaker off, disconnect the circuits neutral from the neutral bar and disconnect the equipment grounding conductor from the ground bar, all circuit conductors are then isolated for readings.

I never go to such lengths. Too often I find ground faults where a bare ground and a hot wire makes contact in receptacle and switch boxes. I do service work at a lot of older apartments. Improperly mounted devices that spring in and out of the wall when plugging in, or the practice of back-stabbing devices are the culprit 90+% of the time. Now and then, I find it in the panel, but super rare. I have found a lot of ground faults from where whoever stripped the Romex cut cross ways with a razor knife and cut into and exposed the conductors, leading to a fault.

 
Here’s a simple way using logic. Start by opening the receptacle used to vacuum. It could be reasoned the load of the vacuum brought forth a deficiency in the circuit, somewhere. Start where it plugged in. If you dont see anything try to logically reason how the circuit may be routed based on what devices you can reason are connected to it and work back to the breaker. If you can deduce half way point, you could open another receptacle box at that point, break the circuit. Try the breaker again to figure a direction to go. It’s a back and forth way of trouble shooting but I usually find faults this way fairly quick. 20-30 minutes tops unless i have to move a lot of furniture 

 

After working these apartments all these years, it’s funny all units are wired typically wired the exact same, but others buildings in the complex I have found will be wired different indicating a different crew of men.

 

[Kid Rich]

We had a gcfi that would trip occasionally. It finally got to the point it would not work at all. Traced the circuit back and found a receptacle that the wire had never been tightened correctly.

kR

[John Kloehr]

Thanks for the encouragement to keep looking. The one where I used the vacuum was fine, and was at the end of the string. Or perhaps one of several ends.

 

Split the "distance" (number of outlets/lights on the circuit by distance to the breaker box) and opened up a GFCI outlet in a bathroom:

 

 

Opened up all boxes in the area, no other burned wiring in those. Looks like when the box was wired, one of the black wires had a nick next to the crimp. That failed slowly, heating everything up. It somehow did arc to the neutral crimp. I could smell it as soon as I removed the cover plate.

 

Removed the plug and cut out a bunch of burned wire and the crimps. Used fresh wire nuts on the remaining stubs. Off to buy a blank plate as I have never used that plug.

 

Not exactly a code compliant repair, but everything else works again. I'll watch for problems and sniff for smells for a while; at some point I will either need to fix this right or bulldoze the house. Kind of favor the bulldozer, and be cheaper and easier in the long run.

[Dirty Dan Dawkins]

14 minutes ago, John Kloehr said:

Thanks for the encouragement to keep looking. The one where I used the vacuum was fine, and was at the end of the string. Or perhaps one of several ends.

 

Split the "distance" (number of outlets/lights on the circuit by distance to the breaker box) and opened up a GFCI outlet in a bathroom:

 

 

Opened up all boxes in the area, no other burned wiring in those. Looks like when the box was wired, one of the black wires had a nick next to the crimp. That failed slowly, heating everything up. It somehow did arc to the neutral crimp. I could smell it as soon as I removed the cover plate.

 

Removed the plug and cut out a bunch of burned wire and the crimps. Used fresh wire nuts on the remaining stubs. Off to buy a blank plate as I have never used that plug.

 

Not exactly a code compliant repair, but everything else works again. I'll watch for problems and sniff for smells for a while; at some point I will either need to fix this right or bulldoze the house. Kind of favor the bulldozer, and be cheaper and easier in the long run.

This is a typical crimper an electrician uses to crimp grounds  with.

https://www.homedepot.com/p/Klein-Tools-9-1-2-in-Crimping-Tool-1005SEN/100352095

The cutting portion of the tool extends past the crimp portion of the tool. If you crimp tight into the box it is very easy to accidentally cut into an adjacent conductor. I learned to always, where possibly, have enough wire outside the box to crimp outside of the box. The NEC itself states 6" conductor length in the box. Of course most guys cut those solid grounds off pretty short, twisted them together and put a crimp sleeve on them. Those bulky GFCI's make it tough fitting everything in, they take up so much room. Leviton makes a low profile GFCI.

[Marshal Hangtree]

36 minutes ago, John Kloehr said:

 

 

 

 

I'm betting your problem is the wall paper.

[Eyesa Horg]

Looks like you found that in the nick of time, no pun intended!

[Sedalia Dave]

You have discovered the remnants of a High resistance Arc. I experienced my first one a couple of years ago.  Hooking up the ice maker on the garage fridge and when i pulled it out away from the wall noticed that the cover plate and outlet had scorched marks on them. Secured the power and opened the box only to discover that the outlet was badly melted inside the box. Had to replace the outlet, box and wiring in the wall.

 

I'm thankful that it didn't burn the house down. 

[Three Foot Johnson]

I had a similar problem with a kitchen outlet 'bout five years back - this is what happens when an old house is wired with only one kitchen circuit PLUS a living room light on the same 20 amp breaker.

[John Kloehr]

1 hour ago, Sedalia Dave said:

You have discovered the remnants of a High resistance Arc. I experienced my first one a couple of years ago.  Hooking up the ice maker on the garage fridge and when i pulled it out away from the wall noticed that the cover plate and outlet had scorched marks on them. Secured the power and opened the box only to discover that the outlet was badly melted inside the box. Had to replace the outlet, box and wiring in the wall.

 

I'm thankful that it didn't burn the house down. 

It goes along with my thinking of a HiPot test. The distances in my case had to be "just perfect" to get a short/arc at 120V. Typically, arcs are not sustainable until about 400 V in terms of jumping a gap. In this case, repeated applications of heat worked to melt through the tape around the neutral crimp (and no tape on the hot crimp!). Until it got to the point that things got close enough to spark.

 

In the last week, also added a heater to the RV and a couple other smaller loads to the circuits beyond the arc point, so pushed it over the edge.

 

I got a bit stumped since my ohm meter was not showing a short, but the distance between hot an neutral must have worked down to a just few thousandth of an inch.

 

It is very important after crimping/nutting wires to still physically separate them in the box; these connections were touching with pressure.

[Four-Eyed Buck,SASS #14795]

About a month ago, I replaced an eye on a light post. Thought I had the wire nuts tight, guess what happened when I stuffed everything back into the post...........yup, dead short. Three white wire bundle slipped loose. Had to be in front of the office,too!

[Sedalia Dave]

15 hours ago, Three Foot Johnson said:

I had a similar problem with a kitchen outlet 'bout five years back - this is what happens when an old house is wired with only one kitchen circuit PLUS a living room light on the same 20 amp breaker.

 

That is what my outlet looked like. Strange thing though is that the fridge was the only thing on that circuit.

[Three Foot Johnson]

A refrigerator is supposed to have its own dedicated circuit.

[Finagler 6853 Life]

I had a circuit of lights and outlets that didn't work at all.  Finally took the GFCI outlet out and found that little red ants had tried to make a best in it and there were lumber of dead bodies in the outlet. This outlet was outside on the deck.

[Capt. James H. Callahan]

Hell's Bells! Thank Heaven the breaker kept doing its job!

JHC