Sidebar: Tree Assessments: A Critical Component of Outage Risk Reduction

In 2012, a new vegetation management standard, American National Standards Institute (ANSI) A300 Part 9, was published and adopted by the utility vegetation management industry. Trees or tree parts falling into conductors cause the majority of outages. One utility has estimated there are more than 10 times as many trees that can cause outages than are typically managed by line clearance.

UVM mandates

Seventy-one percent of tree-related outages are fall-in, and 41% of utilities have a hazard tree program, as reported to CN Utility Consulting. Eighty-one percent of utilities report they remove healthy trees that have multiple leaders with included bark.

By using the level one method of the A300 Part 9, utilities could eliminate the most obvious trees that have a higher probability of causing an outage. Thirty-six percent of utilities stated they remove healthy trees that pose a risk to feeder lines, and 60% of utilities have increased the number of removals in the last five years.