Inspection Detail

Inspection: 104400064 - Laser Applications, Inc.

Inspection Information - Office: Department Of Labor, Licensing, And Regulation Division Of Labor And Industry Maryland Occupational Safety And Health

Investigation Summary

A project engineer informed two maintenance workers that a Rofin-Sinar 1000-watt carbon dioxide laser was not cutting to standards. One of the maintenance workers, who was the head of the maintenance department and an experienced electrician, went with the project engineer, who showed him that the discharge current on one of the eight tetrodes was low. The electrician opened the left door at the front of high-voltage cabinet and pulled out the drawer containing four of the eight tetrodes. He then began adjusting the discharge current using a small pocket screwdriver. The laser was being used in production at the time and being operated by a production worker. The engineer twice asked the electrician if the laser should be deenergized (once before the drawer was opened). The electrician, who had received his training from the laser manufacturer, said not to. The engineer walked away after the electrician completed the adjustments to the left side of the high-voltage cabinet. The electrician then opened the right door, opened the drawer containing the other four tetrodes, and began adjusting them. The second maintenance worker came over, and the two employees discussed the problem with the laser. The electrician then returned to his work. His coworker informed him that his procedure was unsafe and noted that the job could be done safety with the equipment deenergized. The electrician ignored this advice and continued to work. As the second maintenance worker turned leave, he heard and saw sparking and saw his coworker slump to the floor. The electrician had contacted energized parts operating at 21.5 to 30 kilovolts, dc, and was electrocuted. The manufacturer had equipped each of the high-voltage cabinet doors with an interlock to deenergize the enclosed circuits; however, the interlocks on both front doors had been bypassed during the adjustment and might even have been bypassed well beforehand.

Keywords: E GI IV, ELECTRICAL, ELECTRICIAN, ELECTROCUTED, LASER, ELECTRICAL WORK, INTERLOCK, LOCKOUT, ELEC CIRC PART--MISC