I was testing outlets in a kitchen when I ran across an odd thing.
When I plugged my 3 light tester into the GFCI outlet it tripped instantly. This also happened in a second GFCI farther down the counter. The test button, on hand held, was not depressed. Both GFCI’s functioned normally with the internal test buttons and downstream protected outlets showed normal and did trip the GFCI’s on the hand held tester in the normal fashion.
I tried this a few times always with the same result. Other GFCI outlets in the home all tested normally with the 3 light and with their internal testers.
Do any of you have ideas about what is going on here? I wrote them up as I found them and recommended replacement.