In ladder diagrams, which components are located between L1 and the loads?

• A. The power supply
• B. The wiring harness
• C. The input devices
• D. The output devices

Answer: (C)

In ladder diagrams, L1 is the hot line on the left, and the path from L1 to the load goes through the control elements that sense real-world conditions. The components located between L1 and the loads are the input devices—things like pushbuttons, limit switches, and sensors. They sit in the rung to provide or interrupt the current path based on their state. When an input device is actuated (closed, for example), it allows current to flow toward the right side of the rung and energize the output device (coil/relay), which then powers the load. The power supply is simply the source of L1 and L2, not a component sitting in the route between L1 and the loads; the wiring harness is just the cables; and the output devices, while they drive the loads, are located after the input devices on the right side of the rung.