I lately encountered a melted cable in a new construction. And can't really figure out why. Hoping ya'll got some idears. Story goes like this.
A friend of mine had three different people work on her new house new electrical installation. After walls we're covered one of those guys was trying to decipher the others labeling system or lack thereof. While fiddling around in a switch box he head a popping sound, smelled burning and purportedly ran to the panel and flipped off the breaker, as it hadn't tripped automatically. He didn't say anything about it until somebody else noticed some crispy cable. This cable was a 14/3.
New cable was run to the same switch box. During this time the licensed electrician on the job was fired. Not for this incident but rather for being an uncooperative jerk. Thus information from him is not available. While trouble shooting the rest of the circuits an AFCI wasn't holding and it was decided to uncover the joist bay above the panel. It was found that the original 14/3 that fried had melted through the sheath and almost started a fire along a five-foot section of this run. A scary looking situation with charred joists and blackened fiberglass. This blackened section had four more cables run along side of it. The remainder of the fired 14/3 was inspected and found to have not damaged any other adjacent cables.
At this point the damaged sections of the wiring have been repaired and all runs have been accounted for, hopefully. The question remains, why didn't the breaker trip? Other then a faulty breaker I have one other hypothesis. Perhaps while this guy was testing where cables we're run with the black wire live he shorted over to the red wire that was run in the same cable on the other leg of the 240v. This guy is adamant that the red wire was not connected to anything at the panel during his testing. If he is correct perhaps he had inadvertently let it rest against one of the bus bars (no comment). In this hypothesis each hot lead is on opposing legs of the panel. Would even this scenario result in a severely burned up cable without tripping the breaker?
Sorry for the long story. Any thoughts?
A friend of mine had three different people work on her new house new electrical installation. After walls we're covered one of those guys was trying to decipher the others labeling system or lack thereof. While fiddling around in a switch box he head a popping sound, smelled burning and purportedly ran to the panel and flipped off the breaker, as it hadn't tripped automatically. He didn't say anything about it until somebody else noticed some crispy cable. This cable was a 14/3.
New cable was run to the same switch box. During this time the licensed electrician on the job was fired. Not for this incident but rather for being an uncooperative jerk. Thus information from him is not available. While trouble shooting the rest of the circuits an AFCI wasn't holding and it was decided to uncover the joist bay above the panel. It was found that the original 14/3 that fried had melted through the sheath and almost started a fire along a five-foot section of this run. A scary looking situation with charred joists and blackened fiberglass. This blackened section had four more cables run along side of it. The remainder of the fired 14/3 was inspected and found to have not damaged any other adjacent cables.
At this point the damaged sections of the wiring have been repaired and all runs have been accounted for, hopefully. The question remains, why didn't the breaker trip? Other then a faulty breaker I have one other hypothesis. Perhaps while this guy was testing where cables we're run with the black wire live he shorted over to the red wire that was run in the same cable on the other leg of the 240v. This guy is adamant that the red wire was not connected to anything at the panel during his testing. If he is correct perhaps he had inadvertently let it rest against one of the bus bars (no comment). In this hypothesis each hot lead is on opposing legs of the panel. Would even this scenario result in a severely burned up cable without tripping the breaker?
Sorry for the long story. Any thoughts?