How to Measure Amps With a Multimeter
Analog and digital multimeters measure current, voltage and resistance. Unlike voltage and resistance measurements, current is measured in series rather than in parallel. The meter must be in-line with the circuit, not connected across a component. Some digital multimeters provide an audible warning if connected improperly, but be aware that analog meters can be damaged.
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Instructions
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Find a point to connect the meter in series. For example, the meter may be inserted between a positive battery terminal and its circuit connection, measuring total DC current. One end of a resistor can be desoldered and lifted from a circuit board, and the meter connected between the lead and pad to measure current in that subassembly.
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Connect a digital multimeter to measure current up to 10 amperes. The Fluke 87 has two current measuring inputs, one for amperes and the other for milliamps. This meter automatically displays both AC and DC readings without the need to change settings. It also offers auto-ranging. The 10 amp input is fused for protection and the meter provides an audible warning if the leads are in the current inputs when voltage is selected.
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On an analog multimeter, the current inputs may be above the selector dial. Measure current with an analog meter, but take precautions to prevent damage. The Simpson 260 is an example of this type of meter. Like the digital multimeter, it has a fused 10-amp input and a separate 10-microamp input, but it must be manually switched between ranges. AC or DC operation is manually selected also. While analog meters are known for being rugged, connecting one improperly can result in damage.
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Tips & Warnings
Never attempt to connect a current-measuring meter to a live circuit. It can result in personal injury and may damage the circuit components.
References
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