Sparks flew when turning on the breaker

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  #1  
Old 05-21-14, 11:48 AM
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Sparks flew when turning on the breaker

Hi, hope someone can help me...I saw that my ceiling fan was wobbling, and so I took it down to see what the problem was. I saw that foolishly the installer of this fan used a wood screw to attach the bracket to the electrical box!! Not surprisingly it was loosening and fortunately didn't fall and injure anyone. Anyway, I replaced the screw with a proper screw and reattached the bracket. I hadn't yet had a chance to put the fan back up, but I turned the breaker back on so that the other items on that circuit could be in use. I don't know why, but when I flipped the breaker on there were some sparks and a popping sound coming from the box, almost like the sound when a light bulb pops. Of course I quickly turned the breaker back off. I have no idea why this happened. It happens to be that the wires were not capped at that exact moment ( although I did afterwards) but the hot wire and the neutral were not even close to touching each other, or the box. In other words, I'm not sure what was different when I turned on the juice then any other time the juice is on and the circuit is running normally. When I turned the breaker back on again, that incident did not repeat itself. And I measured 120 V from hot to neutral. So no idea what occurred. The only thing I'm wondering is perhaps the longer screws that I used to attach the bracket to the box somehow made contact with something?? But all of the wires look properly insulated, albeit on the older side. (Some of them seem to have some kind of crumbling paper-y insulation on top of the plastic). The box has three neutrals together and one red hot wire. That's how the fan was wired. There are also three black wires which were capped off and not in use. I assume they're hot; when I took the nut off the black wires, the exposed portion of wire looked white and green, oxidized. Perhaps that's why it wasn't being used? No idea. Anyway, any suggestions would really be appreciated, because as I am not an electrical expert I would like to understand what happened before I hook everything back up the way that it was before. Thanks!!!
 
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  #2  
Old 05-21-14, 01:49 PM
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It sounds like you had a constant hot along with a switched hot in the box.

The sparks were signs of a short between a hot a a neutral or a ground.

The box should be replaced with one rated for fan support if it is the sole support for the fan.
 
  #3  
Old 05-21-14, 01:53 PM
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Somewhere there is, or was, unwanted metal to metal contact.

Because you saw sparks and heard a "pop", there is now soot or deformed metal or other visible evidence of the short circuit.Turn off the power to that circuit and examine all of the wires and also the inside surface of the box if that is metal.
 
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Old 05-21-14, 03:01 PM
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You said you turned the breaker back off. It should have tripped on a dead short.
 
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Old 05-21-14, 04:40 PM
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thanks for the tips all. I did try to examine the box and wires for anything "fishy" afterwards, and didn't notice anything, but I will have to look again. My noncontact voltage detector did not pick up any voltage when the breaker was off. I'm assuming that greenish oxidized tips of the black wires I mentioned wouldn't be the "damage" that you were referring to? Thanks
 
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Old 05-21-14, 04:46 PM
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Also, bottom line, whatever happened at that point, is it safe to hook the fan back up now? Meaning was that incident a one moment occurrence and since when I turned the breaker off and then back on and it ceased to spark, that indicates that there is not recurring issue? Or maybe this is something that needs to be further investigated and clarified before hooking fan back up? (Box I think is fan rated btw)
 
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Old 05-21-14, 05:04 PM
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If the box doesn't use 10-24 machine screws and have posts instead of ears it isn't fan rated. Even if it is I'd question the integrity of the threads after a wood screw was forced into it.

In any event the fan box needs to be thoroughly inspected for the cause of the short before you go any further.
 
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