The National Labor Relations Board has ordered an election on July 27 to determine union representation at the city-owned J.B. Johnson Nursing Center in Northwest Washington, following an organizing effort marked by allegations that workers have been fired or disciplined for union activities.

Local 82 of the Service Employees International Union sought the election after the union obtained the signatures of 80 employes on union authorization cards, according to local president William K. Hunt. The SEIU seeks to represent some 130 nursing aides, orderlies and maintenance, housekeeping and dietary workers at the 250-bed home at 901 First St. NW.

A spokesman for Continental Care Center, Inc., which runs the nursing home for the city under a $3 million nine-month contract, yesterday denied allegations of unfair labor practices filed by the union and said that any disciplinary actions were "unrelated to union activities."

The organizing effort is part of a national push by the SEIU recently to expand its membership in the growing health care industry, according to Edward W. Neal, a union organizer from Detroit who is coordinating efforts in the District, Maryland and Virginia. Local 82 has 4,000 members and is attempting to organize several large nursing homes in the metropolitan area.

At J.B. Johnson, the union has filed complaints with the NLRB and contends that five employes either have been reprimanded, suspended or, in one case, fired, primarily because of union activities, Hunt said.

In two telegrams to Mayor Marion Barry, the union has asked Barry to intervene to stop what it calls "anti-union activities and intimidation" by Continental Care.

A. Samuel Cook, a lawyer hired by Continental to handle NLRB matters, said that Continental has been "exercising freedom of speech" in presenting to its employes the company's viewpoint about unionization.

"We just leave the decision up to the employes," Cook said. "It is up to them, after hearing both sides, to decide whether they want a union."

Neal said that employes were told by supervisors that if they signed authorization cards they would lose their jobs, a charge that Cook denied.

Most of J.B. Johnson's residents are former patients from St. Elizabeths Hospital who left the psychiatric facility as part of the hospital's ongoing deinstitutionalization effort. Hunt said workers at the home have complained that they have not had enough training in how to cope with psychiatric patients, and that several workers have been injured by the home's residents.

Gwen Hemphill, the mayor's liaison official for labor affairs, said that the union's complaints are being considered by the Department of Human Services, which oversees the home. Officials of the department were not available for comment.