Killed Workers Unaware of Electrical Line Trouble

Three city workers killed July 12 in an underground explosion in Pasadena had no idea that a live, 4,000-volt electrical line in the vault had malfunctioned hours earlier, city officials said Thursday.

Because no one knew about the problems on the line, current was allowed to flow while the three worked on an adjacent 17,000-volt line. While the three were in the underground vault, the 4,000-volt line exploded, killing them instantly.

Information on the 4,000-volt line is included in a forensic engineer’s report on the accident, the worst of its kind in Pasadena history, which is to be released within two weeks.

David Plumb, Water and Power Department general manager, said the report provides the first comprehensive account of the events that caused the death of foreman Walter (Glenn) Wise, 50, of Temple City, a 29-year city employee, and two cable splicers, Brian Miles, 36, of Pasadena and Larry Hokenson, 38, of West Covina.

The three men died in an explosion about 10:25 p.m. in an underground vault in the San Rafael Hills area south of the Rose Bowl.

Originally, authorities believed the 17,000-volt line was the first to malfunction, sparking a fire in the vault.

Authorities were unable to explain the exact cause of the explosion on the 4,000-volt line 1 1/2 hours later that killed the three workers.

Plumb said Thursday that the report, prepared for the Pasadena Water and Power Department by Long Beach forensic engineer Doug Bennett, determined that the 4,000-volt line had actually failed first, causing the 17,000-volt line to explode.

Plumb said there were no warning signs that would have alerted the workers to the problems with the line.

Only when Bennett and city workers retraced the sequence of events that night did they discover that power outages had occurred to customers along the 4,000-volt line before those on the 17,000-volt line.

However, Plumb said that--given what the three knew at the time--he doesn’t believe city workers could have done anything differently to prevent the accident.

It is not clear what would have been done differently had the workers known of the trouble on the 4,000-volt line. However, when trouble was discovered on the 17,000-volt line, it was shut down.

Plumb said the cause of the failure in the 4,000-volt line is still unknown.

“It was probably just an old 4,000-volt splice that blew with the power going up and down that night,” Plumb said.

Current was left flowing through the 4,000-volt line, and others in the vault, while repairs were being made on the 17,000-volt line, Plumb said, a standard practice to avoid cutting off power to customers while repairs are made.

Such practices were to be examined by the team put together by the city to investigate the accident. The team included Bennett, power department staff members and Pasadena Fire Department arson investigators.

The explosion, coupled with a series of similar accidents that have occurred in Southern California over the last three years, prompted the safety division of the Public Utilities Commission to propose a new regulation requiring regular inspections of electrical vaults.