Appendix 1 Tree-Related Conflicts That Can Be a Source of Risk Trees can create risk without structural failure and physical impact on an electric utility line. Conflicts result when trees grow into contact with, or in some cases simply grow close to, energized conductors. This can cause interruptions and electrical service outages, serve as an ignition point for wildfires, or result in restricted access to overhead energized conductors. These conflicts can result in personal injury, death, property damage, and regulatory citation. Common tree-related conflicts associated with electric utility infrastructure are described below. Reliability Trees growing next to or under high-voltage distribution conductors have been known to cause electrical faults when contact is made. Tree growth close to energized transmission conductors can initiate a flash-over across an air gap and electrical fault. In either case the fault may result in an interruption and outage to customers. Step and Touch Potential Touching a tree that is energized represents an indirect contact with the power lines and in some cases may result in injury. Readily Climbable Trees Large trees may grow close enough to power lines such that anyone climbing the tree could come into direct or indirect contact with them. There are three factors with the potential to increase risk: 1. The tree occurs in a location where there is increased likelihood of someone climbing it. 2. The tree crown is easily entered from the ground without the use of aids such as ladders or ropes. 3. The branching structure in the crown allows a climber to reach a position in proximity to an energized conductor. 55