Which method of terminating a wiring device involves pre-installed leads?

The method of terminating a wiring device that involves pre-installed leads is the modular method. This technique is widely used in applications such as data communication and telephone wiring. Modular connectors typically come with pre-terminated leads that are easy to connect without requiring extensive stripping and crimping, which can sometimes lead to unreliable connections.

In modular wiring, the device is designed for a quick and efficient setup, making it user-friendly, especially in situations where multiple connections need to be made swiftly. The pre-installed leads help ensure consistency in connection quality and reduce wiring errors, allowing for a more streamlined installation process. This is particularly beneficial in environments where time and reliability are of the essence.

Other methods like back wire, side wire, and direct connection do not specifically involve pre-installed leads in the same way that modular does, focusing instead on screw or clamp connections with wire strips exposed.