This chapter shall not apply to -

(1)

any contract of the United States or District of Columbia for construction, alteration and/or repair, including painting and decorating of public buildings or public works;

(2)

any work required to be done in accordance with the provisions of the Walsh-Healey Public Contracts Act (41 U.S.C. 35 et seq.);

(3)

any contract for the carriage of freight or personnel by vessel, airplane, bus, truck, express, railway line or oil or gas pipeline where published tariff rates are in effect;

(4)

any contract for the furnishing of services by radio, telephone, telegraph, or cable companies, subject to the Communications Act of 1934 (47 U.S.C. 151 et seq.);

(5)

any contract for public utility services, including electric light and power, water, steam, and gas;

(6)

any employment contract providing for direct services to a Federal agency by an individual or individuals; and

(7)

any contract with the United States Postal Service, the principal purpose of which is the operation of postal contract stations