My home is older, and while 1st floor is grounded, basement has older 2-prong outlets. I decided that at a minimum I should put in a gfci in the laundry room. Inside box there are 3 wires however it does not appear the the ground wire is actually grounded. Test wires, black is hot, white is neutral as they should. Hook up black wire to the HOT LINE side GFCI, and hook up white wire to the other. But it says hot and neutral are reversed on my tester.
If I flip them around, which I can tell is wrong from the screw colors and directions, tester shows it's technically correct with open ground. That just seems off to me.
What could cause that false polarity reversal reading? Dont think it's the tester, I've tried it on other outlets and it's fine. Would no ground throw off the reading? Or just a bad GFCI?