I have a GFCI receptacle that takes 2-5 seconds to trip when testing with a standard 3 prong receptacle tester. The test button on the receptacle trips right away but two of my trustworthy handheld testers (different brands) take much longer. After changing out the GFCI, the circuit can be tripped immediately with the testers.
Is this a common failure mode? I've replaced many that trip unnecessarily or won't reset at all, but this slow-trip is a first for me. (and has now been replaced)
This also leads me to wonder if there is a tester that measures the time to trip. I'm unlikely to notice the difference between 30ms and 300ms when punching the test button, yet this could be a serious hazard with the equipment, right?