What is a conduit piston (mouse) primarily used for?

A conduit piston, often referred to colloquially as a "mouse," is primarily used for installing pull lines into conduits. This tool is designed to be pushed or pulled through the conduit, allowing it to effectively navigate bends and turns within the conduit system. Once the piston is inside the conduit, it creates an efficient way to pull a line through, which can then be used to facilitate the installation of electrical wires or cables.

This application is crucial for electricians who need to run wires through long stretches of conduit, especially when obstacles like bends and junctions can complicate the process. Using a conduit piston minimizes the effort and potential damage to wires, ensuring a smoother installation process. The other options do not accurately describe the primary function of a conduit piston; measuring conduit lengths, sealing ends, or routing cables through walls are tasks managed with different tools or methods in electrical work.