Washington area residents are paying vastly different prices for equal amounts of electricity, according to utility company records.

A somewhat typical Montgomery County household using 750 kilowatt hours of electricity last November was charged $43.68 or nearly 56 percent more than the $28.02 charged the user of 750 kilowatt hours in the Distric of Columbia.

Montgomery households paid between 17 percent and 63 percent more than those in the District for the same quantities of electricity, the records for two winter months show.

Residents of Montgomery and the District receive their electricity from the same utility company, Potomac Electric Power Co., known as Pepco.

Unitility rates are substantially lower in the District than elsewhere in the area.

Prince Giorge's County residents paid Between 21 and 60 pecent more than the District for equivalent amounts.

In Fairfax County the residents paid between 22 and 55 percent more; in Arlington County between 8 and 44 percent more; and in Alexandria between 6 and 60 percent more.

Virginia area residents receive their electricity from Virginia Electric and Power Co. -- Vepco.

Contrary to claims by some consumer activists, utility company records show that Vepco customers are paying slightly less for equivalent amounts of electricity than the Maryland customers of Pepco.

The large price variations occur because the regulatory commissions in the various local jurisdictions operate independently and apparently give little consideration to rates in neighboring areas.

Rates are determined by complex formulas and procedures that include seasonal adjustments, the passthrough through to customers of fuel costs, differing local taxes and other variables -- all of these affecting the price a customer will pay.

The statistics in this article and the accompanuing chart were provided by Pepco and Vepco at the request of The Washington Post. Some special computer runs had to be made by the companies in order to obtain the data.

In addition, the statistics show that the rates are often lower for customers who use more electricity. In other words, energy conservation seems to be discouraged in some cases.

The new National Energy Act -- now the law of the land -- sets energy conservation as a major goal for utility companies.

Rates for District of Columbia users are set by the Public Service Commission. It cinsists of three members appointed by the mayor.

In Maryland rates are set by the state Public Service Commission of five members appointed by the governor.

For Virginia, utility rates are set by the State Corporation Commission -- a three-member group established by the Virginia Constitution. The SCC members are elected by the state legislature and the commission is often considered so powerful that it is referred to as a fourth branch of government.

A top regulatory official who declined to be identified said last week that the variations in charge show that Maryland Pepco customers are esentially subsidizing District customers.

That subsidy could run as high as $10 million, according to some calculaions.

But Pepco senior vice president Paul Dragoumis said Maryland customers were paying a fair rate and District customers were being subsidized not by Maryland but by Pepco stockholders.

Brian Lederer, the District of Columbia official who represents consumers before the Public Service commission, said that Pepco was not losing money in District as Pepco claims.

He said that if Maryland customers think they are paying too much, they should take the matter up with the Maryland commission to get rate reductions.

Four years ago in the District, the commission put a lid on the price of 450 kilowatt hours or less used by any residential customer. That price has not changed since. Maryland and Virginia have no such lid -- referred to as a "lifeline rate" -- for small customers.

The District commission also has been considering Pepco's request for a 15 percent rate increase for a year and a half but approval has not been given. A decision is expected within a few months.

In Maryland, the commission has acted quickly in deciding rate cases. A request by Pepco for a 5.2 percent increase in pending there.

In Virginia, a commission decision on Vepco's request for a 25 percent increase is expected at any time.

The rates shown on the chart apply only to residential and not to commercial customers.