Criticizing the District of Columbia Public Service Commission for taking too long to make decisions and giving too little attention to consumer complaints, a consulting firm has recommended broad changes in the regulation of utilities in the District.

The terms of PSC members should be expanded to five or six years to protect the commissioners from political influence, and the PSC should get its own budget and legal staff, both independent of city hall, according to the consultants' study, made public yesterday.

The report by Temple, Barker & Sloane Inc. of Lexington, Mass., asserts that a total reorganization of the PSC is needed if the District agency is to cope with changes in the utility field.

"The PSC is not adequately equipped in terms of number of employes, types of employes and other resources to meet the emerging regulatory challenges," the consultants warned.

Ordered by the three-member commission several months ago, the consultants' report confirms and repeats previous criticism of the agency that regulates the gas, electric and telephone companies, as well as taxicabs and stockbrokers.

Commission chairwoman Elizabeth Patterson and commissioner Ruth Hankins-Nesbitt could not be reached for comment yesterday. The third seat on the commission is vacant.

One fundamental problem, the consultants said, is the the PSC has never decided whether its job is to be an advocate of consumer interests or a judge, balancing the interest of consumers and utility companies.

Calling on the PSC to publicly proclaim its stand on major issues, the study said the PSC chairman should be given the authority to run the agency with the aid of an executive director. Now, the three commissioners share responsibility for even the smallest decision and frequently bog down in detail, the study said.

The three-year term of PSC members is the shortest of any utility regulators in the country -- the average is 5.7 years -- the study said, so short that commissioners barely learn the complex field before their job is over.

"The short term does not provide sufficient security to be free of political pressure," the study added.

Noting that the number of consumer complaints about PSC-regulated businesses has nearly doubled in the last three years -- from 1,000 in 1976 to 1,975 last year -- the report said that "procedures for handling customers complaints are inadequate."

The District agency takes an average of 15.5 months to make a decision on requests for higher utility rates, while the national average is less than 9 months.

One reason for the delays, the consultants conclude, is the lack of staff at the PSC. Commissioners have only a secretary to help them; each should have an administrative assistant, it was recommended.

Currently provided with lawyers by the city Corporation Counsel, the PSC needs its own legal staff, the report said, echoing recommendations made a few months ago by the District of Columbia Bar Association.

Lacking specially trainined utility lawyers and other professionals in the field, the PSC must hire outside consultants to study complex questions about utility rates. That costs more money and takes more time, the consultants claim.

The report said the commission's budget -- $1.25 million this year -- should be financed entirely by assessing the companies that are regulated by the PSC. About half the current budget comes from general city revenues.

The report also said the PSC should get out of the business of regulating stockbrokers. Some other city agency should license securities dealers because the PSC lacks the staff or skill to do the job, the report concluded.