“Yard” means a required open space on the same lot with a principal use unoccupied and unobstructed by any structure or portion of a structure from 30 inches above the general ground level of the graded lot upward; provided, however, that fences, walls, poles, posts and other customary yard accessories, ornaments and furniture may be permitted in any yard subject to height limitations and requirements limiting obstruction of visibility. (Ord. 454 § 4, 1992)