Abstract: At approximately 2:08 p.m. on May 29, 2005, Employee #1, a worker with a water and power utility distribution district, was testing an underground utility cable. To conduct a Hipot (high potential) test on the cable, he removed an elbow from phase "B" terminal inside a vault (UN697H). His foreman was working outside the vault. They had isolated and grounded the phase "B" cable in the previous vault (UN688H). After removing the elbow, Employee #1 applied a probe removal tool to remove the probe or connecting rod, and an arc flash occurred inside the vault. He fell backward, and his back touched the wall of the vault. Employee #1 was hospitalized for a severe electric shock and burns on his hands, arms, stomach, and back.