General Order 128
Requirements for Supply Systems
Size and Shape
Manholes shall be constructed to provide sufficient working space so that the cables and equipment therein can be properly and safely installed, supported, operated and maintained.
Manholes shall not be constructed with smaller dimensions than those required by Public Utilities Code, Sec. 8051. (Also see Appendix B, Fig. 9, and Appendix D.)
Handholes and subsurface equipment enclosures shall be of sufficient size to house safely the required transformers, switches, cables, splices, connectors and associated apparatus. Such equipment shall be so arranged that it can be safety installed, operated and maintained. (See Appendix B, Fig. 17.)