To maintain a safety factor, horizontal lifelines should be part of what system?

Horizontal lifelines are designed to be part of a complete personal fall arrest system because they provide a means of connection for the worker to a secure anchorage point while allowing movement along a horizontal plane. This system includes various components such as harnesses, lanyards, and secure anchors that work together to minimize the risk of falls during tasks performed at heights.

By integrating horizontal lifelines into a personal fall arrest system, workers can safely traverse areas where there is a risk of falling, while the system ensures that, in the event of a fall, they will be suspended and prevented from hitting the ground. This safety net of connections and supports establishes a critical safety factor, allowing for controlled and secure movement in elevated situations.

The other systems listed, like safety nets or guardrail systems, play essential roles in fall protection but do not specifically address the dynamic aspects of horizontal movement provided by lifelines. Thus, only a complete personal fall arrest system effectively incorporates all necessary elements for maintaining safety while using horizontal lifelines.