Illuminating appliances designed for post mounting shall be securely and rigidly attached to a post. Posts shall be rigidly mounted. The strength and rigidity of posts greater than 3 feet (0.9 m) in height shall be at least equivalent to that of a 2 1/2 inches (64 mm) diameter post constructed of 0.064 inch (1.6 mm) thick steel or a 1 inch (25 mm) schedule 40 steel pipe. Posts 3 feet (0.9 m) or less in height shall not be smaller than a 3/4 inch (20 mm) Schedule 40 steel pipe. Drain openings shall be provided near the base of posts where there is a possibility of water collecting inside them.