How to Measure Amps With a Digital Multimeter

Multimeters can be set to measure current in amps.

To find the amount of current a device uses, you can measure amps with a digital multimeter. At times, it's necessary to know the amperage rating of an electrical component so you can use it in conjunction with other devices. Replacement parts also have to be matched for amperage ratings to work properly. The multimeter reading will fall within the amperage rating for a device tested.

Difficulty:

Moderate

Instructions

1. Turn the digital multimeter on. Most digital systems run a self-check before they are ready for use. Allow a minute for the meter to complete its testing.

2. Set the function selector to read amps from battery power or alternating current. The function setting (A~) measures alternating current in amps, or AAC; (A=) measures direct current in amps, or ADC.

3. Set the range so the maximum is well above the highest reading expected. This will protect the meter from getting overloaded. If you overshoot the range and cannot get a reading, set it lower.

4. Connect the leads to the proper terminals for measuring current. Connect the black lead to the "COM," or common terminal. Connect the red lead to a terminal marked for low- or high-current measuring. The low-reading terminal may be identified as "300mA." This would give readings in milliamps; 1 milliamp equals .001 amps. Multiply by 1,000 to get the figure in amps.

5. Break into the circuit to measure its current. Set the red probe on one open end and the black probe on the other. This may require cutting a wire to get the probes between the circulating current. The idea is to let the current flow through the digital multimeter to allow it to get a reading.

Tips & Warnings

• The resistance rating of the meter should be a lot less than 1 ohm to get a measurement of current. Higher resistance will reduce the current flow and give an erroneously low reading.