To power 120-volt loads only, how should the two secondary windings be connected?

For powering 120-volt loads, connecting the two secondary windings in parallel is the appropriate choice. When windings are connected in parallel, they match the voltage rating while allowing for increased current capacity. Each winding provides the same voltage, which maintains the 120 volts needed for the loads.

In a parallel connection, if one winding is loaded, the other can assist in sharing the load, ensuring that the overall output remains stable at 120 volts. This configuration is particularly beneficial for maintaining proper voltage levels while powering multiple loads or when dealing with varying load conditions.

Other connection types, such as series connections, would result in an increased voltage (in this case, 240 volts if both windings are 120 volts each), which is not suitable for 120-volt applications. The terms "direct" and "single" do not specifically indicate a valid electrical connection configuration relevant to this scenario. Therefore, parallel is the most effective and safe method for connecting the windings to ensure they can properly supply the required voltage for the loads.