Where I live (Suburban Maryland just outside of DC), they don't trim the branches away from the power lines. At all. I see branches growing between powerlines that are no more than 4 inches apart, and even growing around the lines themselves.

Every time we have high winds (thunderstorm, etc), the power flickers, browns, and sometimes blacks altogether, usually just long enough to kill anything not on a UPS. Very, very annoying. When I was in NC, Duke Power kept the powerlines much clearer - only hurricanes and ice storms seemed to cut power.

-jk