Relationships of National Electrical Safety Code Vertical Clearances and Potentially Conflicting Activity

The development of the vertical clearance requirements of the National Electrical Safety Code (NESC) [1] is briefly discussed and illustrated. Diagrams and tables are provided to summarize the clearances which generally apply in each land category and show the relationship of these clearances to the potential conflicting activities underneath the line. Comments on intended applications are included to aid engineers in understanding vertical clearance requirements and in developing special clearances for applications not specified in the NESC.