What is the minimum safe distance from a power line to allow when installing an antenna?
Why The standard is a fall-distance rule: site the antenna or tower so that if the whole structure topples in any direction, nothing on it can get within 10 feet of the power conductors. That means the separation has to be at least the full height of the antenna or mast plus 10 feet, because contact with a live line during a fall or during erection is usually fatal. Antenna work near utility lines is the single largest cause of amateur radio fatalities.
Watch out The choice about the height of the power line sounds like a reasonable clearance rule, but it ignores how tall your own antenna is, and a tall tower could still reach the wires when it falls.
Think 'fall zone plus 10 feet': if it tips over, it must not come within 10 feet of the wires.