California Code, Public Utilities Code - PUC § 8055

No person shall build or rebuild or maintain any subway, manhole, chamber, or underground room used, or to be used, to contain, encase, cover, or conduct any wire, cable, or appliance to conduct or handle electricity, unless such subway, manhole, chamber, or underground room is kept at all times in a sanitary condition and free from stagnant water, seepage, or other drainage, or any offensive matter dangerous to health, either by sewer connection or otherwise.  This section does not apply to any subway, manhole, chamber, or underground room within which it is not intended or required that any human being perform work or labor, or be employed.