On what setting should a meter be placed to ensure that a motion detector is receiving power from the control panel or power supply?

On what setting should a meter be placed to ensure that a motion detector is receiving power from the control panel or power supply?

• A. VAC
• B. DAC
• C. ADC
• D. VDC

Answer: (D)

The power to a motion detector in most burglar and residential fire alarm systems is DC. To verify it’s actually receiving power, set the meter to DC voltage and measure across the detector’s power terminals. This reads the steady DC supply (often 12V or 24V), which is what powers the device. Using the AC voltage setting wouldn’t give a meaningful read for a DC supply and could mislead you. The other options aren’t appropriate meter settings for this purpose—they relate to data conversion rather than measuring voltage. So, set the meter to DC voltage to confirm proper power from the control panel or power supply.

The power to a motion detector in most burglar and residential fire alarm systems is DC. To verify it’s actually receiving power, set the meter to DC voltage and measure across the detector’s power terminals. This reads the steady DC supply (often 12V or 24V), which is what powers the device. Using the AC voltage setting wouldn’t give a meaningful read for a DC supply and could mislead you. The other options aren’t appropriate meter settings for this purpose—they relate to data conversion rather than measuring voltage. So, set the meter to DC voltage to confirm proper power from the control panel or power supply.