Separate valves, readily accessible, shall be placed at the foot of each riser line, on all branches to exterior hose bibbs, on hot water storage tanks, and on supplies to fixtures. All valves shall be the same size as the pipe in which they are installed and shall be installed on all risers and all branch lines to fixtures. Where shut-off valves are concealed in construction, an access panel shall be provided. If the construction is fireresistance rated, the access panel shall be a labeled door of the required fire-resistance rating. Installation of access panels in stairway enclosures is prohibited.