NCCER Electrical Level 2 – Control Systems and Fundamental Concepts (Module 26211-23) Practice Test

Control wiring’s job is to carry control signals from pushbuttons and switches to energize the coil of a contactor or other control device. When those signals complete the circuit, the coil energizes, pulling in the contactor and closing the main power contacts so the motor can start. This separation between control wiring and the power circuit keeps low-control currents isolated from high motor currents, which enhances safety and simplifies control design. Control circuits are typically designed for lower currents and voltages (for example 120V AC or 24V DC) and may include devices like timers, relays, interlocks, and overload protection that govern the control logic.

The main motor current is carried by the power wiring that feeds the motor through the closed contacts; control wiring does not carry the full motor current. Control wiring is not simply insulation, and it does not store energy—the energy primarily drives the coil to actuate the control device, while any energy storage is not a function of the control conductors themselves.