Resources & Insights

The Often-Treacherous Business of Tree-Trimming

August 3, 2017

It happened again.

An arborist was electrocuted and killed while trimming a tree in the backyard of a home in Littleton in mid-June.

tree trimming risks
CCIG VP Michael Kline.

It was mid-morning and the man was 30 feet up in an ash tree when it happened. There was a power line that ran perpendicular to the tree and the worker may somehow have come into contact with it.

It’s not news to anyone who works in the tree-trimming business that electricity can be deadly. And yet accidents like this happen. A lot.

It’s why tree-trimming consistently ranks among the most dangerous occupations in the U.S., with dozens of deaths every year.

Proper training and licensing help. Several years ago, the Tree Care Industry Association published an analysis of more than 400 fatalities that were reported from 2009 through 2013. Only 9 percent involved tree-care association members who would have been trained in how best to stay safe.

Under OSHA rules, only qualified line-clearance tree trimmers are allowed within 10 feet of energized power lines.

To be qualified for such work, OSHA says, a person must be “knowledgeable in the construction and operation of electric power generation, transmission, or distribution equipment … along with the associated hazards.”

Even then, qualified workers are allowed to work within the 10-foot requirement only if the utility company is notified beforehand to discuss de-energizing, grounding or shielding power lines.

Electrocution can occur by direct or indirect contact, or electrical arcing.

Direct contact happens when a person’s body touches two energized conductors at the same time, or touches one energized conductor and a path to the ground.

Indirect contact occurs when equipment, tree branches, or other conductive objects become energized. Electrical arcing can take place when electricity jumps from a power line to a nearby object, such as a pole pruner.

Utility companies try to prune trees before they pose a risk to their power lines. But factors such as swaying in the wind, sagging with ice/snow weight, and uprooting in storms are examples of problems that can occur without warning – even if the trees are not in contact with wires.

Michael Kline is a CCIG Assistant Vice President. Reach him at or 720-212-2042.

Also read: Getting Your Return-to-Work Program Working

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