Working on my kitchen remodel and I am rerouting the range vent wire (14 ga on a 15 amp breaker). I had turned off the breaker a few days earlier when I removed the old vent hood and forgot that I turned it back on to allow use of a ceiling fan. So I am starting to install a new outlet on the end of the old wire and I chomp down on the romex with my nice Knipex dikes to clean up the end. After removing the wire nuts I had installed just to be safe. My left hand is holding the romex while my right hand is squeezing the dikes. Not being too smart, this isn't the first time I have done this. Typically a few sparks and the breaker trips in a few milliseconds and the dikes now become a wire stripper due to the arc on the cutter. Well, this time it shoots an arc of fire probably 4 inches directly onto the fingers of my left hand turning the skin black and hurting like heck. No zapping, just an arc burn. Well, after running cold water on my fingers for a few minutes I wonder if the breaker ever tripped. I check the panel and, no, the breaker is not tripped, even after causing a dead short. What gives besides my own stupidity? I presume the 38 year old Federal-Pacific breaker is bad and am wondering if there is a way to test the other breakers to make sure they will trip. Closer inspection of the wire leads me to think the black on my (pic is after being washed with soap and water) fingers is more soot from the burned insulation than it is charred skin. A few days will tell.
My other thought is that I didn't get a clean cut due to a, ahem, previous, similar incident which grooved the cutter, allowing the wire to remain in contact with the dikes resulting in an extended welder like arc rather than a true dead short.