Washington Gas Light Co. and Baltimore Gas and Electric Co., which is seeking a $142.5 million rate hike, reported higher earnings for the 12 months ended Jan. 31. Both increases were attributed to higher rates paid by the utilities' customers.

BG&E reported earnings of $150.4 million ($4.13 a share) compared with $119.7 million ($3.58) in the same period the year before.

BG&E's increased earnings came despite a decline in the sale of both total kilowatt hours of electricity and natural gas, company officials said.

"The increase in earnings is primarily due to the higher service rates authorized by the Public Service Commission of Maryland which became effective Feb. 11, 1982," the company said.

BG&E has come under fire from consumer and industrial groups for its 11 1/2 percent rate hike request submitted to the PSC. Inflation and rising operating costs make the increase necessary, said Charles Franklin, a company spokesman.

BG&E would net $96.5 million from the $142.6 million increase, Franklin said. The increased earnings would amount to a $45.5 million savings that would be passed on to customers when the Crain plant in suburban Baltimore is coverted from oil to coal, Franklin said.

WGL posted profits of $19.4 million ($3.41) compared with $18.1 million ($3.57) the year before. Lower per-share earnings reflect more shares outstanding.

Washington Gas, which also attributed improved earnings to more customers served, has received rate increases recently of 4 percent, $9.4 million, in Maryland and 6.8 percent, $14.3 million, in the District.

Scope Inc. yesterday posted a loss of $666,516 for 1982 after discontiued operations compared with a loss of $1.96 million in 1981. Sales slipped to $10.7 million from $11.2 million the year before.

Fourth-quarter sales grew to $2.2 million from $2.1 million, but the company posted a loss of $213,371 compared with profits of $258,744 (21 cents a share) in 1981.

Scope, based in Reston, provides technical services and products to government and industrial customers. The firm spun off its two largest subsidiaries, Repco Inc. and National Controls Inc., last June in an effort to improve its bottom line.