“…San Francisco has many high-voltage overhead wires. Wooden ladders are preferred because they don’t conduct electricity. Crafted from aged ash, Douglas fir and hickory woods, these ladders are sturdier and last longer.
The largest ladder made by the artisans is 50 feet, weighs 350 pounds and takes six firefighters to lift. Raising of the 50ft. wooden ladder, an art in and of itself, is done frequently as firefighters respond to many fire calls each day.” —http://www.sf-fire.org