Railing shall be installed along the edges of every open-sided floor, working platform, runway or balcony which is 6 feet or more above floor or ground level and along the edges of all other platforms or openings in walls, floors or ground levels where the safety of persons is involved. Railings or handrailings shall be installed on all stairways 3 feet or more in height.
34 Pa. Code § 47.231
This section cited in 34 Pa. Code § 47.253 (relating to access to platforms).