may read, 115/230 V, indicating the motor can be connected to either a 115 V supply or a 230 V supply. Dual-voltage motors have two run windings that must be connected properly, as shown in Figure 25‑42. For lower voltage, the run windings are connected in parallel (providing lower resis- tance). For higher voltage, the windings are connected in series, doubling the resistance. The magnetic fields of the two run windings must rotate in the same direction. If one field is “left” and the other is “right,” opposing polarities will cause the rotor to lock. The factory connects the motor windings to terminals located in the terminal box. Most dual-voltage motors are equipped with quick connect terminals for ease of change from one voltage to the other. Instructions for placement of these terminals are inside the terminal box cover. Figure 25‑43 depicts the proper placement of terminals on an open-type dual-voltage motor. Run Run Run Run 120 V 240 V A B Goodheart-Willcox Publisher Figure 25‑42. Dual-voltage motor run winding con- nections. A—For the lower voltage, the windings are connected in parallel (for lower resistance). B—For high-voltage operation, the windings are connected in series (for high resistance). High Voltage Wiring Low Voltage Wiring A B C Goodheart-Willcox Publisher Figure 25‑43. Changing a dual-voltage motor from one voltage to another. A—Motor wiring diagram on data plate showing factory-installed internal connections at the terminal board. B—For high voltage, the wires connect the run windings in series. C—For low voltage, the wires connect the windings in parallel for lower resistance. 508 Heating and Cooling Essentials Copyright Goodheart-Willcox Co., Inc.