Some thoughts on how to safely use an extension ladder.
Identify where the power lines are before you pick up your ladder. Make sure you are vigilant when walking around with the ladder.
To carry an extension ladder, stand it upright, and then grab the rung with your dominate hand just below your reach, and tilt the ladder back on that shoulder. The ladder will be mostly upright and is easy to walk with and maneuver. If you need to go under something (eg, power lines), tilt the ladder back on your shoulder while pulling it forward (so it will end up parallel with the ground, with your shoulder under it at the halfway point).
If the roof is walkable, when you place your ladder at the roof, give yourself at least your own height (eg 6 ft) of rungs above the gutter. Getting off the ladder is relatively easy either way, but getting back on the ladder from the roof is much easier if you have the ladder to hold on to while getting on.
Never step on a rung above the gutter. Especially if the ladder is at a sizeable angle, this would cause the gutter to act like a pivot, and could swing the bottom of the ladder off the ground.
Ladder leveling feet (like these) are a must have. Just jiggle the ladder up and down vertically, and the feet will fall into place nice and level.
If you're on wet or loose soil, flip the ladder feet so rather than being parallel with the ground, they are perpendicular and dig into the soil.
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