A GFCI installed near a sink has this sticker on it. From what I gather online, this means the outlet was installed on place of an old 2 wire outlet, and it's safe anyway, and up to code. But it's not shutting off when I press the test button. Is that normal for an ungrounded GFCI? Is it supposed to test with the button even when no equipment is grounded?
When equipment ground is not present, GFCI devices should test properly.
However, if equipment ground is not present, external GFCI testers there or at downline outlets should not test successfully. Their built-in 3-lamp tester should only display one yellow light. If it displays two but doesn't trip the GFCI, that means a bootleg ground, which makes the GFCI's protection worthless.