Utilities Rate Decision: The California Public Utilities Commission is expected to issue a final decision Tuesday that will set six investor-owned utilities' 1995 allowable return on equity--a part of a regulated utility's version of profit margin. The annual process began this year with applications filed in May by the utilities, followed by those of other interested parties such as consumer groups. A PUC administrative law judge has held hearings on the applications. Generally higher returns compared to those of 1994 are ecommended this year, largely reflecting higher interest rates. Last year, for example, Southern California Edison Co. was allowed a return of 11%; next year, if accepted by the commissioners this week, the return will increase to 11.7%. Other utilities awaiting final word are Pacific Gas & Electric Co., San Diego Gas & Electric Co., Southern California Gas Co., Sierra Pacific Power Co. and Southwest Gas Corp., a Nevada-based company that distributes natural gas in some rural parts of California. The utilities' return on what they charge customers for power--the other side of the profit picture for regulated utilities--is decided every three years. Both processes would probably be replaced under the restructuring proposed for the state's electric utilities.