SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/elec-meter-com-lead

When measuring AC voltage with a digital multimeter, the black lead goes in which jack?

Black goes in COM, red in the V jack.

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  1. COM ✔
  2. A
  3. mA

Why: COM is the common reference for all measurements. The red lead goes in the V input, never the A input, when you measure voltage.

Huh, didn't know that: Fluke says to connect the black lead first and red second.

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References

Answer: COM. COM is the common reference for all measurements. The red lead goes in the V input, never the A input, when you measure voltage.

  1. Fluke: How to Measure AC Voltage with a Digital Multimeter www.fluke.com/en-us/learn/blog/digital-multimeters/how-to-measure-ac-voltage-with-a-digital-multimeter
    Insert the black lead into the COM jack.
    Checked 2026-10-10.

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