How to Check Voltage on an Outlet

Anyone involved in electrical maintenance needs to know how to check voltage on an outlet. In order to test this, you’ll need to use a multimeter or electrical tester. Because this test is done with the outlet energized make sure not to touch the metal part of the test leads to each other or to your body.

North American Outlet Layout

If an outlet is wired correctly the large vertical slot will be connected to the neutral wire. The smaller vertical slot will be connected to the 120v hot wire. And the rounded slot will be connected to the ground wire.

When testing the voltage in an outlet you may need to angle your test leads so they are pressed up against the sides of the outlet slots to get a reading. Especially with smaller test leads like the ones on the Fluke 117.

How to test

Testing voltage between hot and neutral
  • If your multimeter has removable test leads put them in the correct ports. The black lead goes in the com port and the red lead in the voltage port.
  • Set your meter to the AC voltage setting. If your meter has an auto-voltage setting that can be used as well.
  • Put one lead in the narrow vertical slot of the outlet. This should be the energized portion of the outlet.
  • Put your second lead in the larger vertical slot. Your meter should now display roughly 120v AC.
  • Move the test lead from the neutral slot to the ground slot. Your tester should still display around 120v. If your meter doesn’t display voltage it’s possible that the outlet is wired incorrectly or the system isn’t properly grounded.

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