New rules for the Affordable Care Act spell out for the first time a federal method to define the workload of part-time college instructors, but the formula will not necessarily require schools to provide the instructors with health-care coverage.

The question of how to count hours worked by adjunct faculty members has been debated for more than a year on many campuses — one of myriad ways the 2010 health-care law is affecting the nation’s workforce. Colleges employ hundreds of thousands of part-time instructors as a way to contain costs. Adjuncts are especially numerous in community colleges and regional public universities, which are squeezed by tight state budgets. Experts say most adjuncts don’t get health coverage through colleges.

Worried about possible expansion of health-care expenses, community colleges in Virginia and elsewhere have imposed caps on the number of classes part-time instructors may teach. In doing so, the colleges aim to minimize their costs under a new federal mandate that requires large employers to offer health insurance to personnel who work 30 hours a week or more.

Rules the Obama administration announced this week say that a “reasonable” way to tally hours for part-timers is to assume that they work an hour and 15 minutes on activities such as grading assignments and preparing lessons for every hour spent on classroom teaching. The administration also declared that instructors should be given credit for time they are required to spend in “office hours” for students or in faculty meetings.

The rules indicated that more federal guidance could come in the future and that colleges could determine other ways to count the number of hours adjuncts work.

Maria Maisto, president and executive director of New Faculty Majority, an adjunct advocacy group based in Ohio, said she was pleased by the rules because she thinks they set “a floor, rather than a ceiling” for tallying the hours that part-timers work. She said the rules will spotlight what advocates consider often poor working conditions for the instructional staff that form the backbone of many public institutions.

“It’s doing exactly what we wanted, to force the conversation back onto campuses,” Maisto said.

David Baime, senior vice president for government relations and research at the American Association of Community Colleges, said his group was happy with the regulation. “We believe that in most cases, it will not result in required additional health-care expenditures for our institutions,” he said.

Exactly how much work instructors perform outside the classroom varies significantly from subject to subject, depending on the number of students in a class and their preparation. “That is something that’s really almost impossible to estimate,” said Dana Wood, an adjunct instructor of English as a second language at Prince George’s Community College. “Some classes take more time than others.”

Wood said he hopes colleges will not cut the amount of work available to part-timers who are struggling to make ends meet.

That is what happened last year to many adjunct faculty members in Virginia. The state’s community college system employed 7,440 part-time instructors in fall 2013, far more than its 2,852 full-time faculty members.

In May, under orders from state leaders to contain health-care costs for part-time employees, the community college system set new limits on the course load of its adjunct faculty. They were allowed to teach no more than seven credit hours in the summer semester and 10 each in the fall and spring semesters. Credit hours are academic units that roughly correspond to the number of hours a class is in session each week.

Glenn DuBois, chancellor of the 23-college system, told part-time faculty at the time that “maximum semester credit hours cannot be exceeded under any circumstance; and no waiver can be granted for this policy.” Officials estimate that three-quarters of the system’s adjunct instructors were unaffected.

Kevin Pace, 35, an adjunct music instructor at Northern Virginia Community College, saw his course load and pay drop significantly as a result. Pace said he has scrambled to find additional work to support himself and his wife, including offering private guitar and bass lessons and teaching part time in West Virginia.

“We’ve had lots of teachers move back in with their parents,” Pace said. “They’re in their 40s. Some people have lost their homes. It’s awful.” Pace said adjunct faculty deserve better pay.

It is unclear whether Virginia community colleges will ease the limits on adjunct course loads as a result of the new rules from the Obama administration. It appears that faculty members teaching 10 credit hours a semester would be averaging less than 30 hours a week using the new federal definition.

The new rules “may result in some adjuncts seeing their hours go back up a bit,” said Steven Bloom, director of federal relations for the American Council on Education, an advocacy group representing college presidents.

Jeffrey J. Kraus, a spokesman for Virginia community colleges, said system officials “will be analyzing” the new rules.