Abstract: A CREW, CONSISTING OF FOUR EMPLOYEES, WAS PLACING 8-INCH STEEL PIPE, 30 FEET IN LENGTH, ALONG AN OPEN TRENCH WITH A CATERPILLAR SIDEBOOM PIPELAYING TRACTOR (MODEL 561HB). THE TRACTOR WAS OPERATING DIRECTLY BENEATH A 24.9-KILOVOLT OVERHEAD POWER LINE AND HAD A BOOM THAT WAS 27 FEET, 7 INCHES IN LENGTH. THE FOREMAN HAD THE OPERATOR MOVE THE TRACTOR BACKWARD ABOUT 1 FOOT. AS THE OPERATOR DID SO, THE BOOM APPARENTLY HIT THE LOWER ENERGIZED OVERHEAD POWER LINE. THE FOREMAN AND TWO OTHER EMPLOYEES WERE IN HAND CONTACT WITH THE PIPE AND ATTACHMENTS. WHEN THE BOOM CONTACTED THE ENERGIZED LINE, THE OPERATOR SAW A FLASH OF LIGHT, HEARD A SHOUT, AND DROPPED THE BOOM. ONE OF THE TWO OTHER EMPLOYEES WAS ELECTROCUTED, AND THE SECOND RECEIVED AN ELECTRIC SHOCK AND INJURED HIS NECK WHEN HE FELL INTO THE OPEN TRENCH. THE FOREMAN RECEIVED AN ELECTRIC SHOCK, WAS TREATED AT A HOSPITAL, AND WAS RELEASED. (THE TRACTOR OPERATOR WAS NOT INJURED.)