This guide will identify factors that contribute to lightning-caused faults on overhead distribution lines and suggest improvements to existing and new constructions. This guide is limited to the protection of distribution-line insulation for system voltages 69 kV and below. Equipment protection considerations are covered in IEEE Std C62.22-1991. The purpose of this guide is to present alternatives for reducing lightning-caused flashovers on overhead distribution lines. Revision Standard - Superseded. Measures for improving the lightning protection performance of schemes applied to overhead power distribution lines are discussed in this guide.