Updating 2 prong to 3 prong outlets
This GFCI must be labeled as a GFCI without an equipment ground.Simply replacing an older 2-prong outlet with a 3-prong outlet can be hazardous, because the receptacle will appear to be functional with a ground, but in fact there isn’t one.Whether or not the yoke provides an adequate ground, depends completely on the device.Post a picture of inside the box and the receptacle.
It is possible to retrofit a new three-prong or GFCI receptacle into the same receptacle box without any rewiring, as long as the box itself is grounded.
I'm even more confused now that the receptacle tester said that they were correct. Are there ground wires in the box (you'll have to remove the cover plate, and possibly the receptacle to see)?
Is there a brass colored tab on the yoke where the mounting screw attaches the receptacle to the box (you'll have to remove the cover plate to see)?
I don't know too much about replacing outlets, only what I've read online or through You Tube videos. Some outlets have been replaced (brand new kitchen) but some are still the old 2 prong.
I bought a receptacle tester and tested the newer style outlets, which all tested as correct wiring.
Arc-fault circuit-interrupter and ground-fault circuit-interrupter type receptacles shall be installed in a readily accessible location.