When such number has been designated by the public works director, the owner or occupant of such house or building shall cause a painted, carved or cast duplicate of such number at least three inches (3") in height and of a shade in contrast to the background upon which the number is mounted to be placed in a conspicuous position upon the front of such house or building, in a permanent, stationary and durable manner, unobstructed at all times by vines, screens or anything that would tend to hide or obscure the number, and so that the number will be clearly perceptible from a distance of one hundred fifty feet (150'). (Prior code § 41-6-7)