Arc Flash at 110 Vac

Here is the story: He went home from work here, and started to install a breaker in his breaker panel at home. The main was off, and the breaker installed, romex run, and tightened to the breaker. He then wanted to check his job and turned the main on, beautiful, no problems. But, now instead of turning off the main again to tighten the connector to the panel, he tightened the connector energized! When that happened, he eventually cut through a section of insulation and arced the wire to ground. A simple 110 volt flash.

He came in the next day and told me about the incident. Up until then, he was a "NON-BELIVER" as I classify them. I asked him what happened and what did he see. He gave me all the equipment (So I can use it in my classes) and said he saw a bright light, loud pop, and pain in his hand nearest the cable.

He came away with a 1st degree burn to his left hand, as the picture shows.

Now he was still wearing his FR's when he got home, because he didn't change yet, just started working. If his clothes were flammable, could they have caught fire and melted into his skin? It is very possible!!

Roger Nolter
rnolter@yahoo.com
IEEE Electrical Safety Forum