General Order 128
 Section III
 Requirements for Supply Systems
 
        
35.3    Warning Signs
 
        
Warning signs indicating high voltage shall be installed on an 
interior surface, or barrier if present, inside the entrance of vaults, manholes, 
handholes, pad mounted transformer compartments, and other above ground enclosures 
containing exposed live parts above 750 volts. Such warning signs shall also 
be installed on an exterior surface of all such pad mounted transformer compartments 
and other above ground enclosures. Such signs shall be clearly visible to 
a person in position to open any such access door, other opening, or barrier.