Before hoisting persons and to assure that the hoisting compartments are clear of obstructions, empty hoist conveyances shall be operated at least one round trip after:
(a) Any hoist or shaft repairs or related equipment repairs that might restrict or obstruct conveyance clearance;
(b) Any oversize or overweight material or equipment trips that might restrict or obstruct conveyance clearance;
(c) Blasting in or near the shaft that might restrict or obstruct conveyance clearance; or
(d) Remaining idle for one shift or longer.