Cone Method Vs. Rolling Sphere Method 1

[corbin801]

Hello,

This question pertains to lightning protection in substation design. When running overhead static wires for lightning protection, when is the Rolling Sphere Method preferred or required instead of the easier Cone Method to determine lightning protection coverage?


Thanks

 

[jghrist]

The cone method is inadequate for high masts or shield wires because it does not take side strokes into consideration. Applying the rolling sphere method to horizontal shield wires is not difficult. See IEEE Std 998, IEEE Guide for Direct Lightning Stroke Shielding of Substations, which discusses both methods.