Fire crews were called just after 10 a.m. to the mountains above Temple Valley in Windward Oahu to help an injured worker contracted by the Hawaiian Electric Company.
A HECO spokesman said that man slipped at a project for the company.
The injured man is part of a contracted crew working on improvements to support structures that carry transmission lines which bring power over the mountains, according to a HECO spokesperson.
The man's right knee was injured.
His knee was in a splint and the injury is not life-threatening.