What is the common return path for car motors?

The common return path for car motors is through one running rail. This arrangement is typical in many transit systems, where the electrical current supplied to the motor travels through one rail and returns through the other rail, allowing for efficient operation of the electric traction motors.

Using the running rail as a return path minimizes the amount of wiring needed, as the rails serve both to conduct electricity to the car motors and to return current to the power supply. This design not only reduces infrastructure costs but also enhances safety by keeping the electrical components centralized along the rail system.

When considering other options, while the chassis and ground can theoretically serve as return paths in certain electrical systems, they do not provide the same efficiency or operational reliability as utilizing the running rail. Additionally, a separate power line is not commonly used because it would introduce unnecessary complexity and cost into the system. The infrastructure is optimized for the dual rail setup, making it the most practical and standard approach in transit applications.