transitive. In electrical apparatus: To direct (a current) by means of a switch; to put on or off, i.e. connect or disconnect with a battery, or…

to loop in transitive. To connect into an electric circuit by the loop system.

transitive. To connect (an electric circuit, etc.). Also intransitive of a motor.

to switch in: to bring into a circuit by the operation of a switch; similarly to switch out.