Electrical Hazards and Utility Line Safety Flashcards

Which type of wood is generally considered the MOST dangerous to use near energized conductors because of its electrical conductivity?

Answer: Green (freshly cut) wood with high moisture content

Green wood has high moisture content, which dramatically increases its electrical conductivity and makes it far more dangerous to use near energized lines than dry wood.

What is 'touch potential' and why is it relevant to tree workers after a tree contacts a power line?

Answer: The voltage difference between the ground and an energized object a worker touches simultaneously, creating a path for current flow

Touch potential is the voltage between a worker's hand touching an energized object (like a tree in contact with a line) and their feet on the ground, which drives current through the body.

When a tree or large limb falls across a high-voltage transmission line, which action is PROHIBITED for the tree crew?

Answer: Attempting to remove the tree or limb using any equipment until the utility confirms the line is de-energized and grounded

No equipment operation or removal attempt is permitted until the utility has de-energized and grounded the line, regardless of whether the line appears intact.

How does arc flash differ from direct contact electrocution as a hazard for tree workers near high-voltage lines?

Answer: Arc flash can injure or kill a worker without any physical contact with the conductor, through radiant heat and blast pressure

Arc flash releases tremendous energy — heat, UV radiation, pressure, and molten metal — that can severely injure or kill workers who are near but not touching the conductor.

Which type of rope is PROHIBITED for use as a climbing line or rigging line when working near energized conductors?

Answer: Natural fiber rope (manila, sisal) or any rope that is wet or contaminated

Natural fiber ropes absorb moisture and become conductive; any wet or contaminated rope significantly reduces the insulating properties needed near energized lines.

A utility provides a 'clearance' to work on a distribution line. What does this mean for an arborist crew?

Answer: The utility has de-energized, tested, and grounded the specific circuit, and the crew may proceed within the cleared zone

A utility clearance means the specific circuit has been de-energized, tested for absence of voltage, and grounded — making it safe for authorized workers to operate within the cleared zone.

What OSHA standard primarily governs electrical hazard requirements for tree trimming and removal work performed by utility line-clearance contractors?

Answer: 29 CFR 1910.269 — Electric Power Generation, Transmission, and Distribution

OSHA 29 CFR 1910.269 specifically covers work on or near electrical power generation, transmission, and distribution lines, including utility line-clearance tree trimming operations.