I have found three receptacles in my home for which a three-light receptacle tester indicates open ground. Can I safely resolve this issue by replacing these receptacles with GFCI receptacles? Would that be up to code?
Given the placement of these three, I suspect that they are in a row on the circuit. If this turns out to be true, can I just use one GFCI receptacle at the box closest to the breaker, and then pass power to the other two on the load side of the GFCI?
In case it matters, this is in Chicagoland, so ground is provided by conduit throughout the home.
Best Answer
Receptacles should pick up enough ground via the mounting screw heads to have a 3-light tester report grounded. However, if you are pushing somewhat on the receptacle when you test it, you can actually push it off the mounting screw heads enough to break that ground contact. That's why it's not allowed for receptacles as a grounding method.
The proper method is to either run a ground pigtail to the metal box, or use a receptacle UL-listed as "Self-grounding". That means it has an extra brush to reliably pick up ground from the mounting screw shaft.
If even that does not ground it, then "metal conduit" is a lie, and the branch was installed substandard for Chicago.