I Did Something Stupid...

[Theclash84]

Holy crap? That was from one short circuit event? I wouldn't have expected that.

I guess I've always expected the QO line to be superior internally in addition to externally. I've never researched it, but I might now. Other than trip indication and 3 pole options, I figured there would be something better about them.

After I crapped my pants and disconnected the shorted wires, I flipped the breaker back on. It stayed on. A couple days later I replaced it.

 

[gadfly56]

I have my own "stupid human tricks" story.

We have a number of training panels set up in a large room for the fire alarm techs to get experience with before they hit the customer's site. I was prepping one such, and decided to set up the batteries for one of the panels. I got them in series, and decided to trim the 12-2 AWG FPLP. While said cable was attached to the batteries, all ready to land on the panel battery terminals. The cutter mashed the conductors together, creating a "bolted fault". I saw the insulation starting to smoke and deform. So brilliantly, I decided grab the cable and just yank it off the battery terminals. Honestly, how hot can molten plastic really be? I was successful, but not before I put a nice 2nd degree burn across the palm of my hand. The cherry on top was that our two senior alarm techs were in the room and saw it all go down.

 

[petersonra]

When I was new to the business, we did not have autocad. We actually had drafters with pencils and drafting boards to do our drawings for us. I was kind of lax at checking what the drafters would actually draw, assuming the drafting checker would catch any mistakes.

One time one of the drafters gave me a checked drawing where he had drawn a seal-in circuit for a relay as being wired around the relay coil. I asked him why he drew it that way. He said there was not enough room on the drawing to do it the "other" way. I made him fix it. To this day I have no idea why I happened to notice the mistake. I guess it was different enough from the sketch I gave him to draw from.

Would have made for a nice trip when the relay tried to seal in.

 

[ggunn]

My stupid human trick:

For a while I worked in a PV system training center. In the facility we had a mockup of a standing seam roof where we built arrays on S-5 clamps, and overhead we had several big mercury vapor stadium lights that could put enough light flux on the modules to commission the systems we built.

One day I was troubleshooting a string of modules that was showing zero volts (later I discovered it was due to a badly made up connector in one of the home run conductors), and in the process I had disconnected the positive home run from the DC combiner. Unbeknownst to me, when I jostled the wire I caused the faulty connector on the other end to make contact with the wire. When I went to reconnect the wire I noticed that the strands had gotten splayed by the terminal screw, so thinking that the wire was not energized I grabbed the strands with my fingers to squeeze them back together so I could fit the wire back into the terminal. I was in shorts kneeling on the grounded metal roof and the string Voc was something like 400V.

Two things saved my life. One was that the array was indoors and the only light falling on it at the time was from some fluorescent tubes up on the 20' ceiling. The other was that it was a mockup on the floor and I only fell about three feet when I fell off the roof. If it had been a real roof in sunlight I would not be here to write this.

 

[hillbilly1]

When I was new to the business, we did not have autocad. We actually had drafters with pencils and drafting boards to do our drawings for us. I was kind of lax at checking what the drafters would actually draw, assuming the drafting checker would catch any mistakes.

One time one of the drafters gave me a checked drawing where he had drawn a seal-in circuit for a relay as being wired around the relay coil. I asked him why he drew it that way. He said there was not enough room on the drawing to do it the "other" way. I made him fix it. To this day I have no idea why I happened to notice the mistake. I guess it was different enough from the sketch I gave him to draw from.

Would have made for a nice trip when the relay tried to seal in.

At one time, I don’t know if they ever fixed it, Waffle House had a switch that bypassed the photocell for the exterior lighting. The drawing shown it wired as a dead short from hot to neutral!

 

[FionaZuppa]

Wire looks good, so I'm gonna leave it. For the cost of a beer, I can replace the breaker, so that's what I'm gonna do. Thanks for the feedback all, appreciate the comments.

Ckt to a bathroom? Was it a GFCI or AFCI breaker? Did the stab flash due to some dirt or something, or did the flash exit the body of the breaker at handle or lug area?

 

[4x4dually]

After I crapped my pants and disconnected the shorted wires, I flipped the breaker back on. It stayed on. A couple days later I replaced it.

I did the same thing when we built out house back in 2005. I was doubling 2 NMs in each 3/8 Romex connector. I hadn't noticed that one of the two had slide sideways in the connector when I tightened the screws down. The screws cut into the side of the wire and grounded the hot. When I flipped the breaker on the first time and it light up and popped right above my head...I had two movements. A bowel movement followed by a physical movement. Proverbial schidt and run! LOL. I've double checked every Romex connector since that day...twice.

 

[kwired]

Unusual for a QO to go boom, so if a Homeline has the same guts, should be the same. I’ve had QO and CH breakers that trip without as much as a whimper on a short, but GE and BR you know it! LOL!

The standard single pole 15 and 20 amp QO (and assuming also Homeline) have lower magnetic trip setting than other breakers in the line. Simply putting a double pole breaker in can increase the amount of "boom" that doesn't otherwise happen with a single pole breaker.

This is why single pole QO and Homeline sometimes don't play so well with motors or other high inrush loads, but they do make breakers with a -HM (high magnetic) suffix that have higher magnetic trip setting and they do solve those starting trip issues on such loads. You won't find those HM breakers at the big box stores as a general rule though.

 

[kwired]

After I crapped my pants and disconnected the shorted wires, I flipped the breaker back on. It stayed on. A couple days later I replaced it.

When I was in college and Square D still made the QO breakers in Lincoln, NE I got to tour that plant. In test lab they showed us one their tests - they bolted a three phase fault on load side of a breaker (was probably a unit in the 40-60 amp range) plugged it onto the bus and shut some heavy steel doors. Supposedly available fault current was 10k. It made a pretty big boom when they energized the bus. Smoke was still lingering when they opened the safety doors, breaker was covered in soot, but they pushed handle to off and then turned it on and it appeared to mechanically "reset" though it didn't look like it would be a great idea to use the breaker again.