Abstract: A retractable lifeline safety device usable by workers performing tasks at great heights above the ground. The mechanical components of the safety device are contained within a sealed housing that is filled with a viscous fluid. The sealed housing prevents the introduction of dirt, moisture and other foreign matter into the mechanical mechanism of the safety device, reducing the likelihood that those components may be fouled by dirt and corrosion, which in turn could greatly reduce the effectiveness of the safety device. The safety device is attached to the structure on which the worker is performing the task, and a lifeline such as a cable is withdrawn from the housing thereof, the end of which is attached to a belt or harness worn by the worker. The cable may be easily drawn out of the housing in response to the worker moving about normally in the appropriate work space, and the cable is automatically drawn back into the housing of the safety device as the worker draws closer thereto.