2 rules
service performed in the employ of the United States or any instrumentality of the United States if such service is performed—
(A) in a penal institution of the United States by an inmate thereof;
(B) by any individual as an employee included under section 5351(2) of title 5 , United States Code (relating to certain interns, student nurses, and other student employees of hospitals of the Federal Government), other than as a medical or dental intern or a medical or dental resident in training; or
(C) by any individual as an employee serving on a temporary basis in case of fire, storm, earthquake, flood, or other similar emergency;