The Maryland Public Service Commission has proposed a rule banning gas and electric companies from charging their customers for corporate lobbying, donations to charities, and for some advertising.

A spokesman for the Maryland PSC, which has the authority to decide on rate increase for utilities, says the new rule will formalize a policy that has already been in effect.

The commission recently trimmed approximately $250,000 from the rate increase application of the Baltimore Gas and Electric Co., which included expenditures for public affairs, public relations, a number of advertising costs and donations to charities, according to Marshall E. Stokely, chief auditor for the PSC.

"It is just a matter of principle," according to Stokely, who adds the proposed rule will have "very little impact," and has only come about as the result of a "clamor" raised by consumer groups.

"It is just one way of letting the consumers know their recent increases in gas and electric bills do not include lobbying, donations and several advertising costs," said Frank J. Wasowicz, the PSC's executive secretary.

The new rule defines several types of advertising that cannot be passed off to the consumer, according to PSC officials. Those advertising costs include; promotional advertising, which is aimed at influencing opinions on controversial issues; and, institutional advertising, which is designed to create favorable images of the companies.

Wasowicz said the new rule also incorporates the provisions of the 1976 Maryland General Assembly law, which prohibits utilities from passing off lobbying costs to consumers.

The new rule will also ban gas and electric companies from charging customers for donations made to charities. Consumer groups have argued that it is unfair for the utilities to pass these expenses on to their customers, who might disagree with th expenditures.

In drafting the proposal, the PSC gave the gas and electric utilities the ability to transfer costs to consumers if they can prove in each case that the expenditures are beneficial to the consumer.

The commission is accepting public comments on the proposal through Jan. 30.t will make its decision to adopt or reject the proposed rule in February.

One PSC official said the commission has not included the telephone company in the proposed rule because most of its advertising - such as the yellow pages - ultimately works to lower consumer rates.

The official also said the gas and electric utilities can still make customers pay for some ads that include annual reports, notices about changes and conditions of service and job openings.

In other action, the PSC has approved a 1.9 per cent revenue increase for the Washington Gas Light Co.

The increase will mean that the 200,000 customers in Prince George's Montgomery and Charles counties will pay approximately 70 cents more each months as a result of the decision, according to Stokely.

Stokely said the company originally requested $2.9 million in additional revenues.