Pulling a cable or wire through a conduit is known as "fishing" a conduit. One way to fish poly line through a conduit is through use of a retractable metal fishing tape. Made of thin spring steel and capable of negotiating bends and corners, fishing tape is dispensed from a hand-cranked reel in lengths of over 50 feet. The poly line is attached to the tape and fished to the other end of the conduit. After the fishing tape is removed, the poly line remains to pull a larger rope or wire or cable through.
Air propulsion is another method of sending poly line through a conduit. The poly line is attached to a foam or rubber ball, known as a "mouse," to fit snugly inside the conduit. After the mouse is inserted into the conduit, a bottle of compressed air or a mechanical blower is connected to the conduit. Blasts of air pressure propel the mouse with the poly line attached.
The opposite of air propulsion, the vacuum method efficiently transports poly line from one end of a conduit to the other. Poly line is attached to a foam ball, called a "rat," and inserted into the end of the conduit. At the other end of the conduit is an electric vacuum with an air-tight adapter of appropriate size to fit the conduit. The vacuum is turned on and sucks the rat and the attached poly line through the length of the conduit. The vacuum method, if properly executed, can fish poly line through long conduit spans and around bends and corners.
Open ceiling spaces without conduits present different problems. Trusses, suspended ceiling supports and other structural members may obstruct a straight shot along the desired route of the poly line and cable. A no-frills way of overcoming this is to attach the poly line to a rubber ball and throw the ball through the ceiling space in the desired direction and over obstacles. Long fiberglass rods are also available for this purpose. The rods, extending to lengths of more than 30 feet, pass poly line through ceiling and crawl spaces. Some are equipped with bright LED lights at the end for visibility.