The following issue of Franklin Aid is an expanded and updated version of our November/December 1988 issue. This information is repeated in response to several inquires made to our Hotline personnel.

Single-phase deluxe control boxes and three-phase pump panels typically have two distinct electrical circuits as shown in Figure 1. First is the main line or motor power circuit. This circuit normally runs from the main power disconnect to the motor, through a contactor or starter. These systems also use a second circuit typically known as a control loop or control circuit. Continue reading