Well, I THOUGHT I knew what I was doing...

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  #1  
Old 03-03-03, 06:12 AM
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David Wong
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Well, I THOUGHT I knew what I was doing...

I'm a wiring novice, working from a do-it-yourself book, simply trying to wire a light for my vanity and a couple of receptacles.

So, I have run a wire from my box up into my bathroom, first into one of those ground fault receptacles with the built-in breaker, then into another regular outlet, then into a switch that conrols the light above my vanity and finally into the light fixture itself. Everything is metal boxes.

I left the outlets wired but hanging out of their boxes, then checked everything. Outlets work, light fixture works with the switch. Everything is fine...

So then I start pushing in the wires and screwing in the switch and outlets to their boxes, then I get to the one with the breaker on it and as soon as I push it back and metal touches metal (that is, the screw to hold the outlet to the box connects them to each other) *click!* it throws that breaker on the receptacle. Every single time.

I have pulled everything out, checked and double-checked and triple-checked, and I can't figure out what I'm doing wrong.

Any ideas about what I should look for?
 
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  #2  
Old 03-03-03, 06:29 AM
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taxxman2k
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Check your wires. They should only be stripped enough to go into the holes. ANy more and that could be shorting. Also one of the screws that holds the wire could be grounding out on metal box. I like plastic boxes.

These are just some suggestions from one novice ot another. Sorry I can't help more but might be some things for you to look at.
 
  #3  
Old 03-03-03, 06:33 AM
J
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You're not pushing these back in with the power on, are you? Turn the breaker in the panel off before doing anything.

You are not carefully arranging the wires when you push them back in. Screw the screws all the way in. Fold the wires accordian style. Carefully and slowly push the device back in, keeping the wires neat as you do so. Make sure the grounding wire especially is neat and doesn't touch the screws. Some people like to wrap the device with electrical tape, covering the screws.

It also sounds like your boxes are too small. You didn't use those "handy" boxes, did you. They are too small for most purposes (anything but handy).

P.S. That GFCI receptacle is not a "breaker" in the normal sense of the word. The word "breaker" usually means an overcurrent protection device, and the GFCI is not one of those.
 
  #4  
Old 03-03-03, 07:05 AM
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David Wong
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Wow, thanks for the quick response!

I stripped the wires according to the handy strip guide on the back, and that seems to work out just right once you push them in.

I wrapped the thing in electrical tape anyway, because I thought I had to, though I have since taken it off as I started troubleshooting.

The box was the deepest one they had at Home Depot, and there seems to be plenty of room in there if I arrange the wires neatly, and I certainly tried to ("tried" being the operative word there; it looks okay to my untrained eyes). It doesn't take a massive effort to push it back in or anything, doesn't feel like it's crunching everything up.

The first time I went to screw in everything the breaker was off... but as I started experimenting to find my problem I started leaving it on to try to figure out exactly what I was doing to cause it to throw that breaker in the outlet (or whatever it would be called).

I've tried to be very gentle! Is it possible the problem is elsewhere, other than at the ground fault receptacle? For instance, could a problem at the switch be causing this, since the ground fault is made to go if anything after it on the circuit shorts? Or am I misunderstanding the princple?
 
  #5  
Old 03-03-03, 07:26 AM
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lestrician
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Possibility that your ground and neutral are connected somewhere other than the main panel. The way GFCI's work is to trip when there is a difference in the neutral and the hot. If you disconnect the ground from your GFCI and it works, you're most likely looking at a case where that is true. If so, there are ways to fix it.
 
  #6  
Old 03-03-03, 07:38 AM
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David Wong
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Thanks, I'll try that. I just went and looked at it, and I can't fathom how my ground would be touching bare wire (or screws) on any of it, even after I push it in. The way it folds up back there SHOULD keep it well away from anthing that's not insulated, since nothing is really exposed (I re-taped my screws and I don't have any bare wire showing on back).

Gotta leave for work now; I'll have to come back to it when I get home.
 
  #7  
Old 03-03-03, 07:43 AM
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lestrician
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If you're positive nothing is touching, most likely when you push it in either your hot or neutral is loose. Retighten the screws and try again.
 
  #8  
Old 03-03-03, 02:31 PM
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winkleal
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Are you using NM cable, AC, or conduit? If NM, check to see that you didn't over-tighten the clamps that hold it in the box causing a short between the ground and neutral conductors. If AC, did you use bushings or another method to keep the armor from peircing the insulation on the wires? Finally, if you used conduit, check the insulation on the wires for alligator marks (ridges where it rubbed against the bushings when it was pulled in).

Is any of the wire or boxes close to pipes? If there is a problem with other wiring in the house, the return current could be using the pipes in the house as a pathway, cousing the new GFCI to trip, with nohting wrong with the new wire other than touching a pipe.


Tony
 
  #9  
Old 03-03-03, 02:43 PM
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RickJ6956
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David Wong wrote:
I stripped the wires according to the handy strip guide on the back, and that seems to work out just right once you push them in.
"Push them in" to the holes in the back of the receptacle? If so, you'll find by reading more of this forum that "backstabbing" is not the preferred method. Everyone seems to favor using the screws. For good reason -- backstabs often loosen over time.
 
  #10  
Old 03-03-03, 03:34 PM
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David Wong
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Yes, I'm using the holes on the back. I can just as easily wrap the screws, though. Thanks for the tip.

It's AC cable. I looked around there and it doesn't look like I've shredded the insulation anywhere, though the design of this box seems to do a good job of preventing that unless you're just brutal with it.

There aren't really any metal pipes running near THIS wire, though it's possible there are elsewhere. That's an interesting theory.

I shut off the breaker and started from scratch, actually labeled my Line and Load cables to make absolutely sure I was doing it right, re-wired the whole deal around the screws this time. I re-checked my switch and other receptacle, everything looks good and tight and neat.

I didn't screw in the GF outlet, but left it extended out a couple of inches from the box so I could see clearly that absolutely no wires were touching anything... and I turned on the breaker.

Flipped the switch, light worked fine. I ran my little ink pen-shaped current detector over everything, everything is hot that should be. Then I very lightly touched the front of the GF outlet with the current detector, to see if I was only getting current in one slot...

*Click!*

Off it went. I mean, I can look into that box and see that everything is secure... but as before, if I nudge it, it goes. I thought maybe that somehow I got ahold of a bad receptacle, so I swapped it with another one I had just like it. Exact same behavior.

I'm considering conning one of my more knowledgable friends into coming over and looking at it. I sense that this is beyond my meager intelligence.

Looking back at my first post, I guess I failed to mention that my switch is a dimmer switch (not the nob kind, just looks like a regular switch only it goes on gradually). Does that make any difference? My book didn't seem to think so...
 
  #11  
Old 03-03-03, 05:58 PM
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lestrician
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I personally have never put a dimmer on a GFCI, and am not sure how it would respond, but, if you turn that switch off, and you still have the same situation, it's not because of the dimmer. If, however, when you turn the dimmer on, it creates this same situation, then the dimmer is the most likely culprit.
 
  #12  
Old 03-04-03, 04:24 AM
A
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Yong:

If I may jump in.

When you push the device back into the box, and it trips, can you push the reset button, and cause the test button trip again, Or does the buttons fill harder then what they do when you have the device hanging out and the trip button will not continue to
re-trip?

If this sounds anyway near what you have then there is not enough room, Or unproper arraignment, and there is pressure on the back of the device, putting it in a bind, and causing it to trip.

I have seen this myself.

It is the difference of the device sitting in the box like this:

I
or this:
)
 
  #13  
Old 03-04-03, 06:44 AM
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David Wong
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The thing about the receptacle getting bowed or warped in there is interesting, but something like that occurred to me already when I replaced it with a (supposedly) known good one. I thought either the breaker switch was bad out of the box or that I had broken it somehow while messing with it, physically making it so it wouldn't lock in place.

But the new receptacle was never even screwed into the box, and it did the exact same thing. And really, I haven't been that rough with it. It's a fairly deep box and seems to accommodate everything okay.

I'm starting to turn my attention toward that dimmer switch, because that was the most complicated one to wire, wondering if maybe a loose wire nut or something in there could be throwing my breaker.

Maybe later today I'll pull that sucker out of there and re-do it, make sure I haven't created a short in there. As I said before, everything looks secure in there, but...

Are there any common switch-wiring mistakes that could 1) allow the switch to still work and 2) cause the imbalance that's throwing my breaker?

I want to thank you all for your help, by the way. I have a feeling this is all due to some silly mistake I have made and that I am wasting all this advanced troubleshooting...

I think I've got somebody to come look at it this weekend regardless, but this is bugging me.
 
  #14  
Old 03-04-03, 01:30 PM
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Did you connect a ground to the ground screw on the GFI receptacle? If not, when you touch the yoke to the metal box, which I'm assuming you grounded, the GFI is reading a short between neutral and ground which is creating the problem. Disconnect your load side neutral and ground and test between the two for continuity. If you have continuity, you have a ground / neutral short which wouldn't trip a circuit breaker but would trip a GFI. If you do, then the problem is in one of the downstream boxes, possibly a pinched neutral wire in your light fixture.
 
  #15  
Old 03-04-03, 01:57 PM
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taxxman2k
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What I wonder about the therory of GFCI is the fact that on a main panel the ground and neutral wires are tied together anyways. So how does the outlet differenciate? does it not matter on that end? Only matter on the end with the load or whatever is plugged into the outlet?
 
  #16  
Old 03-04-03, 05:43 PM
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winkleal
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Here is a link to an article from the web page of This Old House that explains how a GFCI works.

http://www.thisoldhouse.com/toh/elec...249536,00.html

Another one is here at Codecheck.com

http://www.codecheck.com/gfci_principal.htm

Tony
 
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