The following are detailed steps and precautions for measuring voltage with a handheld digital multimeter, including both DC and AC voltage measurement methods:

• Always insert the black test lead into the common jack marked "COM."
• Insert the red test lead into the "VΩ" jack (some models are marked "ACV/DCV").

• Turn on the power switch (ON position) and confirm that there are no abnormal indications on the display (such as "LOW"). BAT")

• Turn the function knob to "V⎓" or "DCV"
• If the voltage is unknown, first select the highest range (e.g., 1000V), then gradually adjust down to the appropriate range.

• Touch the red test lead to the positive terminal of the circuit, and the black test lead to the negative terminal (reversing polarity will display a negative value but will not affect the measurement).
• Maintain steady contact between the test leads and the measured point, and read the value and unit directly on the display (e.g., "12.34V").

• Avoid switching ranges during measurement to prevent arc damage to the device.
• "OL" indicates over-range; adjust to a higher range.

• Switch to For mains power measurements, select the "V~" or "ACV" range. For mains power measurements, it is recommended to select a range above 750V.

• Connect the test leads in parallel to the circuit (e.g., the two terminals of an electrical outlet). Polarity does not need to be determined. After the value stabilizes, read the effective value (e.g., "220V").

• When measuring high voltage, wear insulating gloves. Do not operate with one hand.

• Range Selection: Try to keep the measurement between 1/2 and 2/3 of the range to improve accuracy.
• Environmental Safety: Avoid use in humid or flammable environments.
• Device Maintenance: Turn off the power immediately after measurement. Remove the batteries when not in use for extended periods.

The above steps will allow you to safely and accurately perform voltage measurements. Please refer to the device manual for detailed instructions.