GFCI Show Hot/Neutral Reverse

Hey Guys-

This was on an older house that had some of the electrical re-done. New panels that were all romex but half the receptacles in the house had no grounds. On this exterior GFCI, the tester showed it had a ground. But when I pushed the button on the tester to trip it, the lights switched to Hot/Neutral Reverse and would not trip. When I pushed the test button on the GFCI it tripped fine. Does that mean it has a false ground? Thanks.



Not a false ground, NO ground. Your three-light tester cannot trip an ungrounded GFCI. Disregard the light-display when you pushed the test button.

If it’s wired with the older 2-conductor cable but on a GFCI, it’s okay correct? But if it’s wired with a false ground it’s incorrect? Why?

I can understand a false ground on a standard 3-prong receptacle being wrong since it gives a false sense of grounding. But on a GFCI, does it make a difference?

Hope that makes sense…thanks.


Yes a GFCI receptacle can be used a replacement for an ungrounded receptacle. According to the NEC the ungrounded device should have a sticker that states “no equipment ground”.

One other thing to note, had you been grounded and contacting bare metal you could have received a shock by holding open the metallic cover and pressing the test button.

I’m with you Jeff that the tester cannot trip an ungrounded GFCI. But usually when there is no ground, only the middle light is on. In this case however, both the middle and right lights were on indicating that there was a ground.

Not sure if this is germane to this example, but. To the OP, are you aware of what a bootleg ground is or the dangers associated with them?

A bootleg ground is where a jumper is installed between the neutral and grounding terminal. It will fool a 3 light tester and show as grounded. The danger comes as there is now neutral current on the metallic path all the way back to the panel.

My bad, I mis-read your post. I’d say the GFCI is defective or mis-wired. Even a false ground will trip the GFCI.

Is there a difference between a false ground and a bootleg?

No difference. . .

Kenny -

IMHO, you’re thinking too hard. Like JP said, "It be broke OR not doing its thing properly. Service and correct".

Then move on down the road …