How to Test a GFCI Outlet
Manufacturers generally recommend testing every GFCI monthly, yet surveys of electricians suggest most homeowners have never pressed the test button on their outlets even once.
The correct monthly test procedure
Plug in a small lamp or nightlight so you can visually confirm power is present. Press TEST — the light should go off and the reset button should physically pop out. Press RESET — the light should come back on. If the button won't pop out, won't reset, or the light stays on during the test, the device has failed and needs replacement.
What a plug-in circuit tester adds
A simple three-light plug-in circuit tester, which costs less than a fast-food meal, can confirm correct wiring (proper hot/neutral/ground) at the outlet — something the built-in test button alone can't verify. Many electricians use one during any GFCI inspection specifically to catch line/load or polarity mistakes.