An officer or employee connected with the building department, except one whose only connection is as a member of the board established by this code, shall not be financially interested in the furnishing of labor, material, or appliances for the construction, alteration, or maintenance of a building, structure, service, system or in the making of plans or of specifications thereof, within the jurisdiction of the building department. An officer or employee shall not engage in any other work which is inconsistent with his duties or conflict with the interest of the building department.