Electrical Vault Rules May Tighten : Safety: The PUC may mandate inspection schedules by utilities to reduce hazards posed by the storage units. A recent explosion in one killed three workers.

Concerned about hazards posed by underground electrical vaults, the Public Utilities Commission is moving toward tightening regulations for inspections of the storage units--some of which go unexamined for years.

The proposal, under consideration at the time of a July 12 explosion that killed three Pasadena city employees, is expected to be adopted by the commission this fall. It mandates inspection schedules for the vaults and requires utilities to keep records of the inspections.

Currently, no such regulations exist and it is up to the utilities to inspect the vaults--small, closet-sized rooms made of concrete that house electric power lines and switching equipment about 10 feet under ground.

“Each utility has its own standard,” said Harry Strahl, a PUC safety division employee who prepared the report. “What is considered preventive maintenance to one utility is considered a nuisance to other utilities. Some inspect (vaults) once every 10 years.”

Many utilities, including Pasadena’s city-owned electric company, do not send workers into the vaults unless a problem occurs. Others, such as the Los Angeles Water and Power Department, lack a regular inspection program for all vaults but attempt to send crews to examine them periodically.

Still other utilities, to cut back on costs, devise maintenance schedules with such long intervals between vault visits that there was “critical” and “marked deterioration of equipment,” the PUC report concluded.

Major utilities, including Southern California Edison, Pacific Gas & Electric and San Diego Gas & Electric, say they have maintenance, inspection and record-keeping systems in existence that may already meet the proposed requirement.

The commission’s review was launched more than two years ago after its safety division staff began noticing an increasing number of serious vault accidents in the electrical system operated by Southern California Edison.

On July 10, 1986, a vault exploded under the Indian Hill Mall in Pomona, killing one child and injuring two other children and an adult. The following day, another explosion in Santa Ana caused a flash fire and damaged three parked cars.

A year later, three people were injured in a July 9 explosion in Costa Mesa, and on Nov. 4, 1987, an underground switch exploded in front of the Long Beach City Hall. No one was injured.

Commission staff members reviewed Southern California Edison records from 1980 through the first six months of 1988 and inspected 108 of the electric company’s 16,000 vaults.

Southern California Edison recorded 426 vault “failures”--including explosions--over the 8 1/2 years outlined in the report. The report listed 145 such incidents in Los Angeles County. Regionwide, the number jumped dramatically from about 30 a year to 60 a year in 1983, reaching a peak of 100 explosions in 1986, according to the report.

“After 1982, somebody (at Edison) made a decision to increase the inspection (interval) from two years to five years,” Strahl explained. “Thereafter, the number of incidents started mushrooming.”

According to the report, 80 of the 108 Southern California Edison vaults inspected by the PUC safety division contained standing water. Such water can rust electrical equipment and cause it to fail, the report said.

The report found similar conditions in some vaults maintained by Pacific Gas & Electric and the San Diego Gas & Electric companies.

“They all had deficiencies but apparently Edison had the most deficiencies, which translates to a greater number of accidents,” Strahl said. But he added that Edison also has a far greater number of underground vaults than the other two utilities.

Mike Aldis, Southern California Edison’s manager of distribution operations, questioned some of the report’s findings. He said the increase in the number of explosions may not be directly attributable to lengthened inspection intervals. Since 1985, Edison vaults have been inspected every three years, Aldis said.

He added that standing water in vaults may not necessarily harm the equipment because it is waterproof and designed to function even while submerged.

The major effect of the PUC’s new rule may be to tighten standards for municipally owned utilities, such as those in Los Angeles and Pasadena.

The PUC does not oversee the operations of municipally owned utilities, but many of them voluntarily comply with the state’s safety requirements, said Bill Lewis, general superintendent of support functions for the Los Angeles Water and Power Department.

Los Angeles is now trying to establish an inspection and maintenance program to comply with the proposal, Lewis said.

“In today’s world of lawsuits, if there’s a state safety order out there, we’re going to comply with it,” Lewis said.

The city-owned utility is still in court over a lawsuit filed by workers injured in a July 8, 1988, explosion in an electrical vault on Spring Street. Six workers were injured but all have since returned to work, said Robert McMillen, a Los Angeles water and power engineer.

Pasadena has not established a regular inspection program for its thousands of vaults because of the sheer number of vaults and the impossibility of predicting electrical malfunctions, said Henry Lee, assistant general manager of the Pasadena Water and Power Department.

“You can’t see when the insulation goes bad,” Lee said. “There’s really nothing you can see. (A failure) can happen then or it can happen 100 years from now.”

A city report on the cause of the explosion is expected to be issued Friday.

The vault in which the three Pasadena workers died had last been entered for repairs in March, 1988. Lee said he doubts that an inspection before the accident would have revealed anything. The vault contained no transformers or switches, only four power cables of 17,000, 4,000, 240 and 110 volts.

Nonetheless, Pasadena will comply with the utilities commission, Lee said. “It’s a prudent thing to do and a safety issue,” he said.