General Order 128
 Section IV
 Requirements for Communication Systems
 
42.5    Openings
     
        
No manhole access opening shall be less than 26 inches in diameter 
 if circular in shape or 26 inches by 24 inches if rectangular in shape. Safe
 access shall be provided from the opening to the floor or other working surface
 (See  Appendix B, Fig. 9
).