weird electrical fault

[James Baker SD]

I do most of my own wiring in the shop and feel OK with what I do. But I have a weird problem in the outside outlets (original with house) that totally confuses me as to what is happening.

My main panel outside has two GFI circuits lableled "outdoor outlets". I do not exactly know which outlet is on which breaker, but we have outlets around the house, some in the overhang controlled by light sensors and a few scattered in the garden for Christmas lights (that's what the house blueprints say) and have an additional on/off switch indoors.

Outlet closest to panel is controlled by lower breaker, shows 125V between hot and neural (narrow plug, wide plug respectively), 125V between hot and ground, and 0.1 between neutral and ground. So far so good I think. Next outlet in the chain is the same. Third outlet in chain behaves weirdly. If I throw the lower GFI breaker, it reads 0V everywhere. Put the breaker back on and it show nearly 0v between hot and netural, 125V from ground to either hot or neutral. Sure looks like a short, but not bad enough to trip the breaker.
Now the strange part, if I throw the upper GFI breaker to off, then outlet three seems fine, voltages just like outlets 1 and 2. I asssume some other outlets somewhere will be completely off now, but I do not have a map of which outdoor outlets are on which breaker. Seems that the upper breaker (which apparently does not control these 3 outlets) somehow manages to interfere with some and not all the outlets on the adjacent breaker (hence I would assume it uses the other 120V branch).

The house was built in 1975 and the wiring is a nightmare, but I do not see how what I am observing is explained.

[Patrick McCarthy]

So, am I correct in understanding that you have an energized "ground"? (green or, more likely, bare copper in the romex?)

[James Baker SD]

seems more to me that I have an energized neutral as I get 0V from hot to neutral, but 120V from hot to ground and 120V neutral to ground and ONLY in that one outlet, not the others on the breaker.

[Jeff Duncan]

I'm going to suggest tracking all your outlets first. Then when you have all the outlets that are on the 3 lines your tracking, I think maybe you'll find something plugged into it that's wired wrong. This is a fairly easy task, if you haven't done it before I'll outline an easy way for the DIY'r to do it, if you have, then ignore the following…...First step is to get yourself a helper. Now give that person a small portable electronic device. Now shut off all the breakers that you believe are in the area of the ones your testing save for one. You need to have that one circuit live. Have the second person go around and plug the device into every outlet making notes of which ones are live. Also check any light switches in the area. You have now mapped out that circuit! Repeat for additional circuits until you tracked as much as you need to. You can also do this on your own with a radio, it just takes a lot longer;)

By having a map of all your outlets you can check each one to see if you can find the problem yourself. And even if you don't and end up needing an electrician, it's still very beneficial to know what breaker controls what in the house;)

good luck,
JeffD

[Jeff Duncan]

Hmmm, I just re-read your last post, have you pulled that one receptacle to see if it's wired correctly? Still strange that shutting off the other circuit would affect it?

JeffD

[Joseph Tarantino]

I'm going to suggest tracking all your outlets first. Then when you have all the outlets that are on the 3 lines your tracking, I think maybe you'll find something plugged into it that's wired wrong. This is a fairly easy task, if you haven't done it before I'll outline an easy way for the DIY'r to do it, if you have, then ignore the following…...First step is to get yourself a helper. Now give that person a small portable electronic device. Now shut off all the breakers that you believe are in the area of the ones your testing save for one. You need to have that one circuit live. Have the second person go around and plug the device into every outlet making notes of which ones are live. Also check any light switches in the area. You have now mapped out that circuit! Repeat for additional circuits until you tracked as much as you need to. You can also do this on your own with a radio, it just takes a lot longer;)

By having a map of all your outlets you can check each one to see if you can find the problem yourself. And even if you don't and end up needing an electrician, it's still very beneficial to know what breaker controls what in the house;)

good luck,
JeffD

+1. great suggestion. did it at my house and it makes sorting out issues, de-energizing appliances/light/plugs really easy. doesn't take long. interesting how many homeowners don't do it, or for that matter, have so little knowledge about how the various systems that make a house work actually operate.

[Dick Mahany]

I had a strange problem in my wiring, although I think it was different than what you are describing. My house was built in 1974 (SF Bay Area code). I had a circuit that began acting up and was fed with a GFI. Intermittent at first, then part of the circuit stopped working all together. The root cause turned out to be that at copper crimp used in one box to connect 3 hots had apparently overheated due to poor contact (they used crimps rather than wire nuts). This resulted in the wires overheating and burning the insulation back about 3" on each conductor. Eventually the connection failed and shorted.

I only found it when I mapped the entire breaker panel to each and every outlet and switch in the house. A local electrician told me that he's seen plenty of bad crimps that began failing after 30 yrs or more. I agree with the suggestions on mapping the entire house to track each and every circuit. Once that is done, then a complete examination of every box in the questionable circuit can be done. I was sick when I finally uncovered the fault and saw the burned wires..............could have been a disaster had I not caught it in time.

[Bob Kalb]

Ground Fault Circuit Breakers are designed to operate on two wire circuits only. If the original wiring to your outdoor outlets was done utilizing a 3 wire circuit ( two hots & one neutral) and the GFI breakers were introduced later by someone unknowledgeable, that might be the problem. You might be getting a hotfeed through the neutral on one of the GFI's. You should check he incoming wiring at the panel to determine ifthat is the case.

[James Baker SD]

Ground Fault Circuit Breakers are designed to operate on two wire circuits only. If the original wiring to your outdoor outlets was done utilizing a 3 wire circuit ( two hots & one neutral) and the GFI breakers were introduced later by someone unknowledgeable, that might be the problem. You might be getting a hotfeed through the neutral on one of the GFI's. You should check he incoming wiring at the panel to determine ifthat is the case.

Bob, Can you explain a bit more? The outlets themselves have a receptacle for the ground pin. And most of them measure 120V from hot to ground pin so I assume the grounds are wired. Sounds like I have some work to do, mapping the outlets to breakers and checking wiring under the outlets. But I did not quite understand the part about GFI not designed for 3 wire circuit. The previous owner did a lot of work to this house, most of it incorrect :-(

[Bob Kalb]

Can you tell me the physical locations of the two GFI breakers in your panel. You refer to them as upper & lower. Are they adjacent to each other, or are they separated by other regular circuit breakers. I need to know to determine if they are fed from the same hot leg in the panel. I have come up with a possible answer to your problem if they are on the same power leg. If they are separated - by how many spaces. Starting at top of panel, 1st c/b is A, next below is B, third is A and so forth.

[James Baker SD]

Bob:

Most of the breakers control two circuits each, a two big breakers control only one and occupy two slots (subpanel inside house and oven). Starting at the top, the GFI are in slots C & D (two double breakers controlling 4 circuits above them). The GFIs control only one circuit each. They are the only 120V circuits which have a slot of their own. They are definitely adjacent locations so I assume on different hot legs, but I don't know that for sure since I haven't taken any breakers out to look at the panel architecture behind them. We also had a 12V transformer controller for garden lights plugged into that circuit that was misbehaving further from the panel than the outlets that alerted me to the problem. I unpluged that unit, so maybe it was part of the problem. What confuses me was seeing the neutral seemingly powered at one outlet of the circuit, but not at the other outlets. I measured them under no load (except for the Fluke) so maybe I have a very high resistance path at the particular outlet (spiders love to make their webs in the strangest places) that looks like a short with just a trickle of miliamps flowing, but isn't enough to trip the breaker far away. Right now I am not using the circuit so I have it off until I have time to understand what is happening.

[Bob Kalb]

James

Almost all panels nowadays use alternate buss positions in a vertical line, however there are some rare oldies that did not account for two pole circuits and put alternate buss left right. If you can get mfg & cat # of your panel I might be able to find spec sheets on it.
My possible solution only works if the GFI's are on the same buss.

[Jason Roehl]

Bob:

Most of the breakers control two circuits each, a two big breakers control only one and occupy two slots (subpanel inside house and oven). Starting at the top, the GFI are in slots C & D (two double breakers controlling 4 circuits above them). The GFIs control only one circuit each. They are the only 120V circuits which have a slot of their own. They are definitely adjacent locations so I assume on different hot legs, but I don't know that for sure since I haven't taken any breakers out to look at the panel architecture behind them. We also had a 12V transformer controller for garden lights plugged into that circuit that was misbehaving further from the panel than the outlets that alerted me to the problem. I unpluged that unit, so maybe it was part of the problem. What confuses me was seeing the neutral seemingly powered at one outlet of the circuit, but not at the other outlets. I measured them under no load (except for the Fluke) so maybe I have a very high resistance path at the particular outlet (spiders love to make their webs in the strangest places) that looks like a short with just a trickle of miliamps flowing, but isn't enough to trip the breaker far away. Right now I am not using the circuit so I have it off until I have time to understand what is happening.

Stick your voltmeter on the screws of the two adjacent breakers while they're on. If you measure 230-250V, they're on different legs. If you measure 0V, they're on the same leg.

[Roger Rayburn]

I'm in the camp of mapping out the circuits. If you don't have a helper, pick up a Circuit Detective from Harbor Freight, for example, it will help you identify what is where. Importantly, test every breaker on every outlet. I have read about one outlet being controlled by two breakers, with symptoms similar to yours. Verifying what every breaker controls is as important as verifying everything that a breaker DOESN'T control. Based on your symptoms, it would also be worthwhile to pick up one of those gizmos you plug into outlets that verifies correct wiring.

[James Baker SD]

Stick your voltmeter on the screws of the two adjacent breakers while they're on. If you measure 230-250V, they're on different legs. If you measure 0V, they're on the same leg.

Thanks for the tip. Just did it and I measure 244V. So back to square one in understanding what is happening.

[David L Morse]

..... have an additional on/off switch indoors....

Does the position of that switch have any effect on the measurements?

[James Baker SD]

Does the position of that switch have any effect on the measurements?

Have not tried that. The indoor switch is to turn on/off the "Christmas" lights outlets which come up through the ground along the driveway (about 150 feet down to public street). Those outlets have never worked since we've been here, so I do not even know what breaker they are on. A reasonable guess is that they are on GFI in the C location and the unswitched outlets along the house exterior are on the GFI in the D location. All the outlets on the east and south walls are on D location. Haven't checked those on the north. Guess I could confirm if the C location breaker is for the Christmas lights by measuring the hot inside that indoor switch. There is nothing (0V) at any of the outlets in the garden. House was a custom build and plans and documentation is minimal. Plus I think it was designed to last the life of the original owners (in their 70's when they built it) without regard for future maintenance.

[Steve Baumgartner]

This reads like an Edgar Allen Poe or Sherlock Holmes "locked room" mystery! And with the same implication: you are necessarily overlooking some possibility. My experience with similar problems has been that in the end the only answer is to open up everything and look for mistakes or sheer weirdness.

Two anecdotes in that vein:

My house is an 1880's Victorian. When we moved in (a bunch of years ago) I plugged in my circular saw to cut a board and when I pulled the trigger, the circuit went dead. So I went down to the basement and found a blown fuse. Replaced that fuse and tried the saw again. No go. So I went searching and found a second box of fuses at the base of the attic stairs. Another fuse blown there. Replaced it. No go! Search again, and when slightly beyond my wits end stumbled across a row of ceramic fuse holders with exposed bus bar wires on a board in one of the attic gable ends (!!!!!). Both sides of each circuit fused! Replaced a blown fuse there and voila, saw works. After completing the sawing I wondered what the other two fuses controlled. So I removed the one in the basement. Saw won't run. Aha! Got that one, I think. Put it back and remove the one in the attic stairs. Saw won't run. What the $#%(*& I think. Put it back and remove the one in the gable end. Saw won't run!!!!! There were three fuses in series on a single branch! By now those of you familiar with old houses will have figured out that the stuff in the gable end was the original service entrance from when the house was wired in 1886, and the main wiring then was knob and tube. Sometime later, someone added more fuses by tacking the box in the attic stairs onto the k&t in the middle of a run. Then later still, someone added a modern fuse panel in the basement, disconnected the original feed to the attic, and back-connected the whole mess to new fuse there. The house has since been completely rewired, but for a long time I left that row of fuses (no longer live) in the attic for amusement.

Story two: my parents bought a new house in Houston TX. At one end of the living room there was a switch that didn't seem to control anything. I opened up that box and found that it was a three-way switch with only two wires attached. Further, in the box was a red wire that was taped off. Aha! thinks I, this was meant to let you turn the living room lights on and off from this end of the room, not just by the switch at the other end. So I reconnected the red wire and threw the switch. Poof! Breaker tripped. To make this story no longer than necessary, after much hair tearing I tracked the problem down to a receptacle in the far wall of the room where on both sides of the receptacle there was a white wire and a black wire connected to the adjacent screws! Fixed that and all was well. Obviously, the builder's electrician (or helper) bungled that connection and couldn't figure out where the problem was, so they just disconnected the switch.

Steve

[James Baker SD]

Well, I may finally have a solution. Maybe an electrician or two might want to weigh in. To summarize problem, outdoor patio and porch outlets were on 20A GFCI breaker that kept tripping. Super light current draw, such as a nightlight to test it was OK, but lawn mower and more importantly, my astronomical telescope, would trip the breaker as soon as powered up. Fluke VOM gave strange readings that did not make sense.

Finally got around to really working on it this week as I just got a new telescope and I really don't want to have to power it from inside the house. Among the things I did and found.

1. Managed to locate all the outlets on this circuit, total of 7 duplex.
2. Previous owner had a 20A breaker installed, but I measured wire diameter as only 14 gauge, so I guess the bigger breaker was his solution to the problem. But it wasn't helping me.
3. I downsized the breaker to 15A GFCI and started to really debug the mess.
4. Thought maybe spiders or something were causing a short in one outlet and leading to problem. Several of the weatherproof covers had broken or missing doors over the outlets. So I bought 7 new outlets and 7 new weatherproof covers.
5. Each outlet had two romax cables into it, one feeding live power from the panel or the circuit next to it but closer to the panel, one feeding the next circuit further from the panel. (except the terminal outlet)

Here's what I think may be the problem, electricians please chime in.
I was using 3rd outlet from panel to try to power lawn mower, shop vac, new telescope (old telescope apparently drew so little current it still usually worked, but not always).
When removing cover from 2nd outlet from panel, I could see that the bare ground wire was entangled in the neutral screws. I suspect that when using outlet #3, my return current path split at outlet #2 with some of current going through the white neutral wire and some through the ground wire. GFCI detected the lower current in the neutral wire and tripped. It was working I guess as it was detecting a harmless ground fault.

Stretching that ground wire fully away from the neutral screws. I then installed a new outlet in location #3. Fluke now reads normal values same as other outlets (maybe original outlet was part of the problem).
I flipped my breaker on and SUCCESS, at least for the moment.
I can run my shopvac, my 13A lawn mower and of course, the new telescope.

I sure hope this is all it was.

James

[Tom M King]

Glad you found the problem, and glad is was something so simple as a ground contacting a neutral. What telescope did you get?

[Ole Anderson]

It is nice to see someone post a resolution to their problem, thanks.

[Chris Padilla]

See, I told you that was the issue! ;) LOL Glad you found it...feels good I bet and thanks for updating the thread!!