This link is a great bit of information to get you started on understanding the scope of the arc flash problem in the electrical industry. This page also has information relating to arc flash regulatory standards, and arc flash labeling.

http://www.industrialsafetysolution.com/arc_flash_resources.php

From the page:

“The electric industry is becoming increasingly aware of a phenomenon known as arc flash, a short circuit that passes through air between two live conductors, or between a live conductor and ground. This short circuit can be accompanied by incredible amounts of heat and pressure, and the results are often deadly. The frequency of reported incidents is on the increase, prompting increased awareness and action in the electric and safety industries.  “