Added a GFCI in a bathroom that had no previous outlet. For supply I ran new cable from a nearby ungrounded ceiling box. Even though there was no ground in ceiling box I hooked bare ground wire to GFCI green ground screw.

There is power to GFCI but it will not trip when tested. My GFCI tester shows open ground. Should I remove the bare ground from the ground screw? Or could new GFCI be bad? I would have tried while there but had to let tenant back in and won't get back till next week. Just want to get a jump on it. Thank you

  • As Ed Beal mentioned, it's usually only legal for a property owner to do work if he resides in the structure.
    – isherwood
    Mar 13, 2020 at 14:00
  • Are you sure the ceiling box isn't grounded, maybe through metal conduit?
    – JACK
    Mar 13, 2020 at 14:02
  • The ceiling box is plastic, no metal. Thanks for all the help.
    – Gary Weber
    Mar 14, 2020 at 18:58
  • Please consider merging your unregistered and registered accounts, which will allow you to edit, comment on any of your posts and accept an answer on your question. Thanks, and welcome to the site!
    – Niall C.
    Mar 14, 2020 at 19:43

2 Answers 2


The test button on the GFCI should work it doesn’t use the ground. The tester uses the ground with a resistor to create a ground fault since the ground is not there the test function will not work with the plug in tester. As long as the test function on the receptacle works the receptacle is protected as required by code.

The electronics compare both the hot and neutral, a imbalance of more than ~5mA will cause a trip. This is a legal method of GFCI protection with a 2 wire circuit.

IF you want to run a ground wire back to the panel that feeds this circuit OR if there is a grounded circuit in the area that is fed from the same panel recent code changes allow a new separate ground wire to be installed. However if the test button on the GFCI works the receptacle is protected.

Just a note, in my jurisdiction a rental requires a licensed electrician to do anything more than replace a device (light, receptacle or switch) for example. I have heard of some that require a license for even those but have not worked in a state that has that strict requirements. I would verify your local regs so you don’t get in trouble.

  • But isn't the OP saying that the test button on the GFCI is not tripping the device? Therefore either the GFCI is defective or not installed properly.
    – HoneyDo
    Mar 13, 2020 at 15:51
  • The op said the tester shows open ground, my answer covered both the tester that will not work without a ground and how the device itself works . “As long as the test function on the receptacle works the receptacle is protected” so I covered all bases. I believe the op is confused because the “tester” did not trip the GFCI. I have been called and had upset customers for this very reason. When the test button in the receptacle works fine.
    – Ed Beal
    Mar 13, 2020 at 16:00

The instructions that come with the tester may or may not be clear, testers need a ground to function. Gardner Bender makes it clear, near the bottom of the user instructions it says "Caution When testing GFCI's installed in two wire systems (no ground wire available) the tester may give a false indication that the GFCI is not functioning properly..."

It says "may" because for instance if it is installed in a metal box that is incidentally grounded it will still trip.

But I don't believe this is a legal installation. NEC 250.130(C) lists the options available connecting grounding conductor for circuit extensions. If you extend a circuit you have to ground it. There is a Informational Note referring to 406.4(D) for use of gfci receptacles, that section refers to replacement of existing receptacles, no reference to new circuit extensions.

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