This design guide contains information on methods to improve the lightning protection performance of overhead distribution lines and is written for the distribution-line designer. This guide recognizes that a perfect line design does not exist and that a series of compromises are made in any distribution-line design. While some parameters such as voltage, routing, and capacity may be predetermined, other decisions are made at the discretion of the designer. The designer may exercise control over structure material and geometry, shielding (if any), amount of insulation, grounding, and placement of arresters. This guide will help the distribution-line designer optimize the line design in light of cost-benefit considerations.