An employee was working on deconstructing a steel electrical tower. He was hooked to the steel of the tower and wearing personal protective equipment. He finished installing rigging on the top arm of the tower and started walking toward the inside body of the tower. As he was transitioning to tie off to the body of the tower with his second lanyard hook, the step below him came loose. The steel that he was tied to did not hold and he fell approximately 20 feet onto a tower arm below. The employee was hospitalized with fractured ribs.