The District of Columbia Minimum Wage and Industrial Safety Board yesterday raised by 29 per cent the minimum wage for an estimated 60,000 clerical and semitechnical workers in the city. The new minimum wage for those covered, effective July 12, will be $2.90 an hour.

The board's decision applies to persons working for such institutions as banks, insurance companies, educational institutions, hospitals, nursery schools, telephone-answering services and those working for doctors, lawyers and other professionals.

Among the job categories covered are secretaries, typists, clerks, telephone operators, cashiers, messengers, receptionists, orderlies and institutional attendants, according to Richard Seideman, the board's executive secretary.

The minimum wage approved yesterday on a 2-to-0 vote with one abstention does not apply to aides at day-care centers, whose new minimum wage will be $2.55. It will not affect persons who work for government agencies, retail stores, beauty and barber shops, laundries, hotels, restaurants and wholesalers.

The minimum wage increase voted yesterday will affect an estimated 8,000 employers. It is 60 cents higher than the minimum wage for similarly employed workers in Maryland and Virginia, Seideman said. But it is 30 cents lower than the $3.20 rate recommended by an advisory committee . The board felt that much of increase would lead to layoffs in the city.

The minimum wage for those affected was last raised in August, 1971, from $1.60 to $2.25 an hour.