On which setting should a meter be placed to check a motion detector’s power?

When checking a motion detector’s power, the appropriate setting to use is VDC, which stands for Voltage Direct Current. Motion detectors typically operate on a low-voltage direct current power supply, often ranging from 5 to 24 volts DC.

Using the VDC setting on a multimeter allows you to measure the actual voltage supplied to the motion detector, ensuring it is receiving the correct power necessary for operation. If the voltage is too low or non-existent, it could indicate an issue with the power supply, wiring, or the motion detector itself.

In contrast, the other settings would not provide the appropriate measurements for assessing the power supply to a motion detector. The AC Voltage setting is used for alternating current systems, which are not applicable here. The Resistance setting measures the opposition to current flow in ohms, helpful for determining the state of a circuit or component but not for assessing power supply. The Current setting measures the flow of electricity in amperes, which is also not needed for verifying voltage levels in this context.