The solenoid is a magnet type thing that, when voltage is applied to the left two terminals, it pulls the solenoid together providing voltage from the bottom of K3 to the top of K3. So when you hook a switch to the bottom and top of K3, you bypass the solenoid completely, and the voltage flows thru your switch to the circuit, it still can be in the solenoid. I've not taken this one apart, and if someone has and it's different, please let me know. We use solenoids and contactors in my irrigation business to control 480v 3 phase to motors and such. Most times I've found solenoid problems to be dirt, and contactor problems to be shorts melting the plastic!