What is primarily used in a power fishing system to pass through a raceway?

In a power fishing system, a string line is primarily used to facilitate the passage of other materials through a raceway. This thin yet strong line acts as a guide and allows installers to pull or "fish" wires through conduits or tight spaces without tangling or damaging them. The string line can be easily maneuvered through the raceway and is capable of withstanding the tension that comes with pulling heavier cables.

String lines are particularly valuable because they can be threaded through complex pathways, allowing professionals to quickly and efficiently set up electrical systems. They also eliminate potential issues that could arise from using bulkier materials, ensuring a smooth installation process.