Voltage Measurement with a Multimeter: Steps and Precautions
Ⅰ. Procedures for Measuring Voltage with a Multimeter
First, set the range selector switch to one of the five ranges marked "V". Select the AC voltage range for AC voltage measurement and the DC voltage range for DC voltage measurement.
Second, connect the multimeter test leads in parallel to the circuit under test. Select an appropriate range according to the approximate value of the measured circuit. Since each dry‑cell battery has a maximum voltage of 1.5 V, the 5 V range can be adopted. On the meter panel, the full‑scale reading of 500 shall be interpreted as 5, i.e. scaled down by a factor of 100. If the pointer points to the 300‑mark scale, the reading is 3 V. Note that the value indicated by the tip of the range‑selector pointer corresponds to the full‑scale reading on the meter scale. Read the actual measured value by scaling accordingly. Except for the resistance range, this reading method applies to all other ranges of the selector
switch.
Finally, in practical measurement, if the approximate value of the measured voltage is unknown, set the switch to the maximum‑voltage range first, then gradually switch down to a suitable range. Pay attention to polarity when measuring DC voltage; reversed test‑lead connections will cause reverse pointer deflection. If the circuit polarity is unknown, set the multimeter to its maximum range and perform a quick test on the circuit. The pointer‑deflection direction will indicate the positive and negative polarities.
Ⅱ. Precautions for Measuring Voltage with a Multimeter
① Before using the multimeter, perform "mechanical zero adjustment". With no measured quantity applied, adjust the multimeter pointer to the zero‑voltage or zero‑current position.
② During operation, do not touch the metal parts of the test leads with your hands. This ensures both measurement accuracy and personal safety.
③ Do not switch ranges while taking measurements, especially when measuring high‑voltage or large‑current signals; otherwise the multimeter may be damaged. If range switching is required, disconnect the test leads first, change the range, and then resume measurement.
④ Place the multimeter horizontally during use to avoid measurement errors. Also keep it away from external magnetic‑field interference.
⑤ After measurement, turn the selector switch to the maximum AC‑voltage range. If the multimeter will remain unused for a long period, remove its internal battery to prevent corrosion of other internal components.
A multimeter can measure resistance, AC voltage and DC voltage. Some multimeters can also measure key transistor parameters and capacitor capacitance. This document introduces multimeters from basic knowledge and practical voltage‑measurement skills to help users master fundamental multimeter operation.
