The six-week-old coal strike has begun to force energy conservation steps in at least four Appalachian states, although government and industry officials say most utilities in the country have stockpiles sufficient to last about another three months.

In the first sign of the strike's impact on energy supplies, three utilities serving 1.2 million customers in western Pennsylvania said they may have to seek mandatory power curtailments by the end of the month and asked Gov. Milton J. Shapp to provide police protection, if necessary, for delivery of non-union coal.

In addition, the Allegheny Power System, which serves 232,000 customers in Pennsylvania, western Maryland, Ohio and West Virginia, called for voluntary curtailment of electricity usage and warned that power curoffs for several hours may be necessary if the strike doesn't end soon.

The three utilities and the Allegheny system are estimated to have enough coal for only 40 to 50 days - roughly half the national average, which the U.S. Department of energy calculates at 85 to 90 days.

"There are trouble spots, but on the average there's a lot of coal," said Alex Ganker, a coal specialist for the Energy Department. As long as the national energy picture is "as good as it looks now," utilities should be able to cooperate and thus aviod localized hardships, Gander said.

The Edison Electric Institude said frozen coal piles have been more of a problem so far than coal shortages. "Some are hurting (because of the strike), but I won't say it's a disastrous situation at this point," said an institute spokesman.

Sources indicated on reason for advance conservation moves by utilities with relatively low stockpiles is the widespread expection that the strike by the United Mine Workers is unlikely to end soon. Bargaining is under way again, after periodic breakdowns, but there is no official word on progress on such bottleneck issues as benefits guarantees and labor force stability.

According to the Associted Press, steel companies report that their coal supplies are adequate, but the two major coal-hauling railroads, the Norfolk & Western and the Chessie System, are suffering. It said the N&W has laid off 4,100 employees and Chessie has dropped 875.

In addition to unprecedented prestrike stockpiles, which averaged more than 100 days for utilities, coal users are receiving supplies from non-union sources - representing roughly 40 per cent of normal production.