Which type of series street light circuit uses only one wire?

The type of series street light circuit that uses only one wire is known as an open loop. This type of circuit operates by utilizing a single conductor for the electrical current to travel through the street lights, with the return path often involving grounding or other electrical pathways.

Open loop systems are designed to simplify wiring and reduce installation costs, making them a popular choice in certain applications. In contrast, closed loop systems typically require two wires for the complete circuit, enabling both current flow and return current to be carried more efficiently. Single wire loop and dual wire configurations also incorporate additional complexities and require more wiring overall. Thus, the open loop system is specifically noted for its ability to function effectively with just one wire.