Abstract: Employee #1 was directed by Employee #2 to enter a newly installed manhole to measure the distance to the service Y connector, as Employee #3 observed from 6 ft away. Employee #1 descended into the manhole without a flashlight and could not see in the darkness. Employee #2 advised Employee #1 to use a cigarette lighter. Employee #1 could not get the lighter to work and climbed up the ladder and handed it to Employee #2. Employee #2 was able to light the lighter and gave it back to Employee #1 with the flame burning. As Employee #1 descended the ladder, the lighter's flame ignited the natural gas vapors that had entered the manhole through unsealed lift holes of a damaged utility gas line. There was an explosion and flash fire. Employee #1 was hospitalized.