Coal supplies are down to "potentially dangerous" levels at electric utilities serving 33 million persons in the east and midwestern United States, President Carter was told yesterday.

"Industrial and commercial cutbacks of electric power are now occurring and job layoffs are imminent unless early resolution of the United Mineworkers . . . contract can be reached," said Stanley G. Schaffer, chairman of the Eastern Central Area Reliability Council, from Pittsburgh in a telegram to Carter.

The council's 18 members own and operate utility systems supplying power in nine states where the 60-day coal strike has had its biggest impact.

Schaffer's telegram said the utilities had taken "every conceivable step" to conserve energy and meet demands of customers in Virginia, Maryland, Indiana, Kentucky, Michigan, Ohio, Pennsylvania, Tennessee and West Virginia.

"In some places they've got the coal but can't move it because it's frozen on the (railroad) cars or the barges. Other places haven't got any, and others don't want to try moving it in because of the strike situation, to avoid creating any violence," said Michael Segel of the Edison Electric Institute, the industry trade association.

The coal strike impact in Maryland and Virginia was primarily felt in the western areas, where Potomac Edison Co. Executive Vice President John McCardell was rebuffed yesterday in his request that both states order emergency energy conservation measures.

Acting Gov. Blair Lee III of Maryland said he would take no action, and Virginia Gov. John N. Dalton said more energy should be purchased from nearby electric systems first. "Although the price is high, the price (of cutbacks in electricity) in the way of inconvenience may be even higher," he said.

Like most of the east-central area utilities, Potomac Edison's coal supplies are down to about 35 days' worth. Most executives estimate that it will take about 25 days from the time a contract is signed to get coal supplies moving again.

"A voluntary (conservation) effort has been in effect for some time, but its effects are very hard to measure," McCardell said. He told the Associated Press that the company might have to seek a rate increase for its 125,000 customers in northwestern Virginia in order to finance power purchases from other systems.

In Pittsburgh executives of Duquesne Light Co., West Penn Power Co. and Pennsylvania Power appealed publicly to customers for a volutary 25 per cent reduction in electricity use. "Each kilowatt saved is a pound of coal," a spokesman said, recommending that businesses turn off floodlights and reduce office hours and that homeowners turn off every fourth light.

Columbus and Central Oil Electric Co. of Columbus, Ohio, reduced voltage 5 per cent yesterday and asked customers to cut back 25 per cent. The utility had already doused streetlights in its southern and central Ohio service area.

"We're in a better position in this area," said Virginia State Corporation Commission chief engineer James Wittine, speaking of Maryland, eastern Virginia, Delaware and the District of Columbia. "We're less reliant on coal here with a substantial portion of our power coming from oil and nuclear plants."

"However, there's a limit on how much power the ones in trouble can buy from the ones that aren't: there's not enough to sustain everyone's power needs," he said.