How to Read & Interpret a Multimeter

A digital multimeter connects to a circuit with a pair of probes.

A multimeter is an electronic device for testing electrical circuits for proper performance. Multimeters are equipped with a settings control to test voltage, amp output and ohms, which is a measure of current resistance. Two probes wired to the multimeter attach to the positive and negative terminals on the circuit. The measurements display on a dial or digital readout, depending on the multimeter model. Once you know what the different measurements mean, it becomes a simple process to read and interpret the results.

Things You'll Need

• Electrical components

Instructions

1. Dial the control knob on the front panel of the multimeter to AC or DC to test alternating current or direct current circuits. AC refers to current flow that reverses direction, such as the household circuit for a table lamp. Direct current refers to a steady voltage in one direction only, such as from a battery to a connected device.

2. Touch and hold the red probe on the multimeter to the positive terminal on the circuit and the black probe to the negative circuit. Check the meter display for the reading, which is in volts. The measurement is the potential electrical difference between the two points in the circuit. The voltage reading shows how much energy is required to move an electric charge between the two points in your circuit.

3. Disconnect the probes and switch the multimeter control to read amps.

4. Touch the probes to the circuit terminals. The reading on the multimeter in amperes is a measurement of the amount of an electric charge passing through the circuit.

5. Disconnect the probes and switch the multimeter control to read ohms.

6. Touch the probes to the circuit terminals. The ohms reading provides a measurement of the resistance to current in the circuit. Another way to understand electrical current is to divide the voltage reading by the ohms (resistance) reading to determine amperage, which is the power of the electrical current passing through the circuit.

Tips & Warnings

• Do not test circuits with a voltage rating above the range of your multimeter.

References

• Doctronics: How to Use a Multimeter
• MSCGINC: Using a Multimeter