To measure current in a switched circuit using a DMM, where should the test leads be placed?

To effectively measure current in a switched circuit using a digital multimeter (DMM), the test leads should be placed on the terminal screws of an open switch. This method ensures that the current can flow through the multimeter, allowing for an accurate measurement. When the switch is open, the circuit is incomplete, and placing the DMM leads across the switch terminals creates a new path for the current to flow, thus enabling the measurement of how much current would flow when the circuit is closed.

In a closed circuit, measuring across the load or at the power source would not provide an accurate reading of the current flowing through the switch itself. Measuring across the load would give the load current reading rather than the total circuit current, and placing the DMM at the power source might not give a clear indication of what current is being controlled by the switch. By placing the leads on the terminal screws of an open switch, the DMM can measure the potential current flowing in that part of the circuit, which is essential for troubleshooting and ensuring safety.