Technicians and managers of the vast Potomac Electric Power Co. electrical network yesterday dominated a D.C. Public Service Commission hearing with complex explanations of how they dealt with these loss of electric power to 100,000 customers caused by the June 27 thunderstorm.

But Edward F. Mitchell, Pepco's senior vice president for system engineering and operations, said the company could not provide information on which neighborhoods were without power for how long - information needed to counter charges of racial discrimination - without spending "thousands of man-hours" over a period of months to compile it.

"They have the highest form of computerization anywhere," shouted John Thornton, a citizen of Northeast Washington as he testified. "They can tell you when a buzzard lands on their line, (but) blatantly and arrogantly they stood here and told us they didn't have the data on which neighboorhoods went out first or came on last."

D.C. People's Counsel Brian Lederer, the official who represents utility consumers, said there is a growing "lack of public confidence, a demoralization among people about utilities. We get a little tired of hearing how difficult it is to prepare (statistics) when it's something the people need.

"People came here to find out what happened and they left feeling angry," Lederer added. PSC chairperson Ruth Hankins-Nesbitt, the PSC's chairperson, said at the meeting's end, "I for one have not gotten all (the information) I'd hoped."

The official Pepco testimony consumed all but about an hour of the commission's time in its tiny bearing room at 1625 I St. NW. As a result, at least 12 of 18 citizen witnesses had to leave before they could testify, even though the PSC had billed the hearing as a chance for citizens - rather than the company - to air their views.

Hankins-Nesbitt said the commission will continue to study the question of what the company might do to speed the pace of restoring service to customers after a storm. Many people were without electricity for several days after the June 27 storm.

The commission also is studying whether to build insurance into the rate structure to pay for food spoilage and other damage resulting from electricity outages. This is a revolutionary concept because utilities are exempt from liability for damages caused by "acts of God."

The racial issue has been raised by several community groups and political candidates - none of whom has any proof for the contention that the homes of black and lower-income people went without electrical power longer than those of others.

All the facts offered by Pepco officials seem to indicate the charge is false. They said, for example, power was out an average of 13 hours in Montgomery County, 14.6 hours in Prince George's and 12 hours in the District.

They repeatedly refused to provide the one set of facts that could indisputably counter the charge - a list showing the time the power was lost and restored in certain neighborhoods. They said their computer is not set up to sort information by neighborhoods.

Mitchell said he was proud of the way Pepco responded to the storm. He said Tantallon and Oxon Hill in Prince George's County were the last areas with large numbers of customers to be restored to service.

He said the entire upper Northwest and lower Southeast of Washington - both areas with large numbers of trees - were without power. Pepco could reduce storm damage significantly, he said, if the city would allow the company to be more thorough in trimming tree branches that threaten electric lines.