The symbol 'S' in electrical diagrams represents which type of switch?

• A. Single Pole
• B. Three-Way
• C. Four-Way
• D. Double Pole

Answer: (A)

A switch in a circuit is defined by how many separate conductors it can control—the number of poles. The symbol S on a diagram marks a switching device, and in simple schematics it most often represents a single-pole switch that opens or closes one conductor between the power source and the load. This is the basic, everyday switch used to control a single circuit path.

Multi-location or more complex switching arrangements, like three-way or four-way switches, involve additional terminals and more than one path or contact, so their symbols and labels reflect those extra connections. A double-pole switch would interrupt two separate conductors at once, which is different from the single path the single-pole switch handles. So, the symbol S corresponds to the simplest form—one pole controlling a single circuit.