I just spent the past three hours attempting to wire an outlet. I had already run the romex, installed the outlet box, and connected the breaker a few months ago. Other projects prevented me from finishing the outlet until today. I wired the outlet without any problem- took me all of 15 minutes, including looking for all of my tools. However, when I plugged a circuit tester into the outlet and turned the breaker on, there was a small blue spark in the breaker box and the breaker tripped back off. Double and tripple-checking my connections did not find any problems. I tried it with a different breaker- same problem. I tried a different outlet, no difference. I even tried the tester on a different circuit and cycled the breaker. Nothing happened. 'Must be a short in the romex', I thought to myself. So I disconnected both ends, went back into the crawl-space and removed it. Using a multimeter, I checked for shorts and opens, but couldn't find anything wrong. There were a few kinks in the line where the cable had to go through tight clearances and a few places where the insulation was slightly abraided (probably from un-stapling the romex), but everything looked intact. Does anybody out there had any idea what went wrong here?