An employee was on a 28-foot extension ladder, running a fiber optic line to a home. The line being run was crossing a street. As he climbed the ladder with it, he was trying to keep tension on it to keep it above any possible traffic. He had ascended to about 12 feet when the ladder started to move, then slid sideways to the pavement. The employee jumped off, landed on his feet, and suffered fractures to both heels.