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Old 08-06-2009, 04:04 PM   #1
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Need help, breaker unstable


Ok this needs a little back story.

My stepdad has some chicken houses, and he asked me to change out a light fixture, in his words, it "had a short" but I didn't check to see what it was actually doing. I went ahead and changed it out, and when I went to turn the breaker back on, it immediately tripped and sparks flew out of about 3 or 4 light fixtures and 1 j-box. I reset the breaker, turned it on again and everything worked fine, for about five minutes or so, then it tripped again.

I reset it again, it held this time for over twenty minutes so I figured everything was ok.

A week or so later he calls me back and says the breaker won't hold. Stays on for about five minutes and trips. I get out there and figure there's some sort of short in the fixtures that sparked the very first time I turned it on, so I pull them all out and inspect them. They all appear fine, so I turn on the breaker and waited for over an hour. It held the whole time even with me flicking the lights off and on several times, and even once flipping the breaker off and back on rapidly several times. Again I figure everything's ok and call it a day. Thought it may have been some weird short in the fixtures and I accidentally fixed it when I pulled them out and put them back.

Now it's two weeks later and he called me again today and says the breaker won't hold at all. Trips immediately off as soon as it's turned on. Sparks flying again throughout those same 3 or 4 fixtures and that j-box. I'm at the end of my rope here and don't know what to do next.

I'm not sure off the top of my head how big the breaker is, but the only things on the circuit are about 30-40 light fixtures, all with incandescent bulbs in them. He says he never had a problem with it holding until I changed the fixture out, but I inspected that one twice and it's a rock solid connection.

Is it possible I have a bad breaker? If so could anything I described have caused it to go out? Any other ideas?

Edit: By the way, I should point that he is between flocks right now, so it's very possible that he's not using the lights during the week or so in between times I've been out there. As far as I know the first time he tries to use them, they wig out like I described.


Last edited by Atroxx; 08-06-2009 at 04:10 PM.
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Old 08-06-2009, 04:15 PM   #2
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Need help, breaker unstable


IF you have sparks from the j-boxes that would be the first place i would check (TURN POWER OFF ) Then open j boxes and look at the wires and there connections make sure they are twisted together good and there are no burn marks on the wires.

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Old 08-06-2009, 04:24 PM   #3
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Need help, breaker unstable


I did check those (right before the time the breaker held for over an hour, so you might be right actually), but the first thing I was going to do tomorrow was open all the boxes and fixtures and re-twist everything and put new wire nuts on.
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Old 08-06-2009, 04:37 PM   #4
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Yes thats another good idea check them also .Dod you take the switch out if you did take it out and make sure the ground wire is not touching or close to. Good Luck
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Old 08-06-2009, 05:17 PM   #5
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Originally Posted by Atroxx View Post
I went ahead and changed it out, and when I went to turn the breaker back on, it immediately tripped and sparks flew out of about 3 or 4 light fixtures and 1 j-box. I reset the breaker...

Is it possible I have a bad breaker? If so could anything I described have caused it to go out? Any other ideas?
Sounds like the breaker did its job just fine, but it's probably shot now! Sparks shooting out of multiple fixtures and J-boxes are a pretty solid sign of a short to ground! Since it works sometimes, it's an intermittent short to ground. Probably a pinched or scraped wire, or loose wire nut somewhere. Check all the wiring in all the boxes very carefully until you find the problem. It's there somewhere.

Circuit breakers are not made to withstand multiple bolted faults. The fault current will severely damage their insides. You need to replace this breaker once you solve the short circuit problem. Not because it was defective before, but because repeatedly closing it into a fault will make it unreliable.
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Old 08-06-2009, 08:11 PM   #6
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Need help, breaker unstable


I gotcha mpoulton. I left a few irrelevant troubleshooting steps out, but suffice it to say I wasn't blindly turning it back on after each trip, lol. I really hope it's something simple like a scraped wire or something. I'm starting to think the original short might've burned some of the insulation off, causing the occasional short. I forgot to mention that the first short was in fact my fault, I had a made a bad connection on the neutral that came loose when I crammed the fixture back in the box.

Could it still throw sparks in several different locations because of one single bad place in the wire though?

@300zx: I can't take the switch out of the circuit because there isn't a real switch in it. The whole system runs through a low voltage control relay system called a Rotem(that's the brand name of it anyway) Anyhow, the breaker box is placed after the Rotem in the circuit, and we're about 98% sure the Rotem isn't the problem because it still works fine for everything else it controls. Also, we took a peek inside and there are no visible burn spots on any of the boards. I know that doesn't necesarily mean it's not the problem, but we're still pretty confident that it works properly.
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Old 08-06-2009, 08:21 PM   #7
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Need help, breaker unstable


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Could it still throw sparks in several different locations because of one single bad place in the wire though?
Yes. I am assuming that this circuit is run in conduit, probably with no grounding conductor (just using the conduit for grounding), right? The fault current returning through the conduit may spark anywhere there is a loose or corroded conduit connection. This may be helpful for troubleshooting - the fault is at least as far "out" on the circuit as the farthest sparking location.

Your control system is definitely not the cause of this problem, since the fault must be downstream of the breaker that is tripping, but be aware that the fault current from this may damage the contactors in the control system.
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Old 08-06-2009, 08:31 PM   #8
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You know, if you put a 100w incand. bulb or a 10A hair dryer across the (120v?) open breaker terminals, you can tell if you're looking at a short without all the drama.
I did this with a 100 Ω 100w rheostat to tell if I was looking at a short or 600w worth of incand. lamps in parallel.


No drama new work short tester
With heavy clip leads, wire a 10A, 120v hair dryer across the turned-off CB that feeds your new work, for 1 or 2 seconds.
If the voltage across the dryer reads more than 72v out of 120v this is more than a 120v, 15A load.
More than 80v, more than a 120v, 20A load.
Wear level 2 arc flash protection for this one. If the voltage across the dryer reads more than 114v this is more than a 120v, 200A load.

Or you can measure across the load.

Last edited by Yoyizit; 08-06-2009 at 08:34 PM.
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Old 08-06-2009, 09:04 PM   #9
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Need help, breaker unstable


The way most chicken houses are wired, I would guess that those lights are the porcelain "keyless" type. Or they might be plastic keyless. If that is the case, then it is also probable that the circuit was "daisy-chained" by using 4 terminal screws on each one -- thus making each fixture guts part of the circuit.

This could make sparks fly out of multiple fixtures when a short circuit condition was encountered.

When you inspect and/or replace any of these fixtures, always connect the circuit conductors together with wirenuts, and pigtail the fixture off from there.

This should eliminate the sparks flying from them. It won't cure the other problem at hand, which is a bad fixture, or wiring downstream.

You can use a 100 watt bulb to troubleshoot the circuit: Place a 100 watt bulb in series with the circuit at the breaker box, and then switch it on. Simply use an extra keyless fixture, and connect the black terminal to the breaker, and the white one to the circuit conductor before it leaves the breaker box.

As long as the short circuit condition remains, the bulb will be lit brightly.

You might have to unscrew all the other bulbs downstream for an effective test using this method.

Then open fixtures along the circuit to narrow down the bad spot. Start at halfway down -- see if the bulb remains lit or not when you break the circuit at that point. If it goes out, the problem is further down the circuit. If it remains lit, the problem is between the breaker box and the -way point.

Then break the circuit -way again -- looking for the indication that the short is still there or not.

You should be able to isolate the problem within a couple of hours troubleshooting using this method.
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Last edited by kbsparky; 08-06-2009 at 09:06 PM.
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Old 08-06-2009, 09:07 PM   #10
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Need help, breaker unstable


IMHO, If the problem with the flying sparks and the breaker tripping, intermittently (Not tripping immediately after activation), this could be a ground fault or short circuit caused by deteriorating insulation. The best way to check for the cause of your problems would be with a "Megger" (Megohmmeter). After de energizing the circuit, of course!

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Old 08-06-2009, 09:14 PM   #11
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Need help, breaker unstable


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Yes. I am assuming that this circuit is run in conduit, probably with no grounding conductor (just using the conduit for grounding), right? The fault current returning through the conduit may spark anywhere there is a loose or corroded conduit connection. This may be helpful for troubleshooting - the fault is at least as far "out" on the circuit as the farthest sparking location.
<snip>
You assume correctly sir, and I think you might have nailed it. The farthest sparking box out from the breaker is either the one I replaced or the one just shy of it, kind of hard to remember when you're staring down a row of 100 or so bulbs lol. That definitely narrows the search down a bit, I was thrown off by the multiple sparks, kind of assumed I was looking at multiple failures. I'll open up those boxes again and redo all those connections. If that doesn't work I think it may be time to call in a pro, I'll post an update tomorrow either way.
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Old 08-06-2009, 09:22 PM   #12
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Need help, breaker unstable


@kbsparky: The fixtures are wired using an electricians loop, so a single bad fixture shouldn't be causing the problem. I don't think so anyway. As for the bulb test method you describe, I'm having a stupid moment right now and I'm having a little trouble visualizing what you're talking about. I know it's probably something simple to do, but I'd rather not try something like that without someone helping me who knows what's going on. If it was something I owned I'd give it a shot, but this is my parents primary income source so I don't want to take any chances know what I mean?

By the way thanks for all the input guys, I'm feeling a lot better about troubleshooting this thing now than I was before.
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Old 08-07-2009, 11:33 AM   #13
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Need help, breaker unstable


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I reset it again, it held this time for over twenty minutes so I figured everything was ok.



Sorry, that's all I got
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Old 08-07-2009, 08:32 PM   #14
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Sorry, that's all I got
wha?


Anyhow, I found the problem. The original short, which again, was my fault, had caused a little bit of the insulation to burn off about a half inch or so up the wire. Clipped off the wire up to the burned spot, ran a pigtail, and Bob's your uncle as the Brit's say.
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Old 08-08-2009, 01:44 AM   #15
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Need help, breaker unstable


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Originally Posted by Yoyizit View Post
You know, if you put a 100w incand. bulb or a 10A hair dryer across the (120v?) open breaker terminals, you can tell if you're looking at a short without all the drama.
I did this with a 100 Ω 100w rheostat to tell if I was looking at a short or 600w worth of incand. lamps in parallel.


No drama new work short tester
With heavy clip leads, wire a 10A, 120v hair dryer across the turned-off CB that feeds your new work, for 1 or 2 seconds.
If the voltage across the dryer reads more than 72v out of 120v this is more than a 120v, 15A load.
More than 80v, more than a 120v, 20A load.
Wear level 2 arc flash protection for this one. If the voltage across the dryer reads more than 114v this is more than a 120v, 200A load.

Or you can measure across the load.
lol, you keep a hair dryer in your bag?

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