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OREGON PUBLIC UTILITY COMMISSION <br /> • <br /> TREE CLEARANCE POLICY ... �' <br /> PURPOSE <br /> The purpose of this policy is to modify and define the tree trimming rules of <br /> ANSI C2, National Electrical Safety Code (NESC) as interpreted by the <br /> administrative authority (Reference -NESC Rules 012, 013, and 218). This policy <br /> is to set forth the specifications and guidelines relating to tree trimming, tree <br /> removal, and line clearance to provide for reasonable service continuity, safety to <br /> the public, and to guard against forest fire damage caused by supply conductors. <br /> POLICY <br /> Trees which may interfere or do interfere with supply conductors should be <br /> trimmed or removed. <br /> A. Specifications and guidelines for line clearances. <br /> 1. The necessary clearance of supply lines from trees is determined by: <br /> • a. Voltage, location, and importance of individual line. <br /> b. The height of the poles and line. <br /> c. The growth habit and final appearance of the trees. <br /> d. Combined movement of trees and conductors under adverse <br /> weather conditions. <br /> e. Sag of conductors at elevated temperatures. <br /> 2. Concept: <br /> a. Transmission lines should have a minimum clearance of ten <br /> feet in all directions. <br /> b. Primary distribution lines. <br /> There should be a minimum 5 -foot clearance between an <br /> energized high voltage distribution conductor and any part of a <br /> tree. This clearance may be reduced to three feet if the tree is <br /> not readily climbable (having sufficient handholds and footholds <br /> to permit an average person to climb easily without using a <br /> • ladder or other special equipment). <br />