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I have a GFCI circuit (GFCI breaker in the breaker box). If I attempt to test this circuit by plugging in my GFI Tester into a standard outlet that is on this GFCI circuit, the GFI Tester lights illuminates showing the proper wiring, however, it does not trip the GFI breaker in the breaker box if I press the test button on the GFCI Tester.

If I press the test button on the GFCI Breaker, it does kill the power to the outlets on that circuit.

So, my question is, what should happen at the breaker box on this circuit when I press the GFI test button on the GFCI Tester? I thought it should trip the breaker or cause the test button at the GFCI breaker to trip but it doesn't.

Does this mean that a device plugged into the receptacle is Not protected or is it still protected even though the breaker doesn't trip?

I have noticed that on another circuit that has a GFCI Receptacle (but not a GFCI Breaker), that if I plug in the GFCI Tester in either that receptacle or one beyond the GFCI Receptable and press the Test button on the GFCI Tester that it trips the GFCI test switch in the GFCI Receptacle.

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    Which tester, and what lights do you see? A picture would help. – J... Jul 10 at 13:02
  • I won't be able to answer this fully until August when we return to our vacation home where this is occurring. I had two different GFCI Testers and I will answer your question in more detail when I am back at that home. One of the testers is a GB--501 and the other is a Southbend. – LAW Jul 11 at 21:20
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It depends on the grounding setup. The pocket tester creates a GFCI fault by using the ground wire. If ground isn’t wired properly, weird stuff happens.

If ground is present and wired correctly:

  • the tester will light 2 yellow lights
  • the GFCI will trip

If ground is absent, and wired correctly (for ground being absent):

  • The tester will light 1 yellow light
  • The GFCI will not trip

If ground is illegally BOOTLEGGED to the outlet:

  • the tester will light 2 yellow lights
  • The GFCI will not trip

So it sounds like your tester is indicating that some son-of-a-Be-Nice-Policy decided to “bootleg” ground on those receptacles, specifically to fool an inspector running around with a tester.

Bootleg grounds are dangerous setups, and they are more dangerous with GFCI because the GFCI hides their hazard. If you get between “hot” on that circuit and “bootleg ground” on that circuit, the GFCI will not protect you.

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  • Any chance it's not a class A breaker and the tester's trip current is below threshold? – BowlOfRed Jul 10 at 3:54
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    Can you elaborate on what 'bootleg' would mean? Is that like using the neutral as ground in a 2-wire situation? – UuDdLrLrSs Jul 10 at 13:06
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    Bootleg ground is when someone creates a 'ground' by connecting ground and neutral at the outlet - which is NOT correct or safe. – Michael Kohne Jul 10 at 13:50
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    @Radar Absolutely. Very possible that Person 1 came along and did just that, and a 3-lamp tester would indicate 1 yellow in that instance. And this would be made OK and approvable by the presence of a “GFCI Protected / No Equipment Ground” sticker which Person 1 neglected to apply, causing a code violation. And then, perhaps Jackass 2 came along, had no idea about the GFCI, because there’s no sticker, and bootlegged ground to get 2 yellow lights to fool the inspector. Now we’re in the danger zone. GFCI+bootleg ground. – Harper - Reinstate Monica Jul 10 at 18:03
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    Another possibility, depending upon the design of the tester, would be that there isn't a good ground connection, but there's enough of a ground connection to make the light glow. Some neon lights can be illuminated with very small amounts of current (which is how neon-based non-contact testers work). If a ground connection can pass 1mA, that might be enough to light a tester, but not enough to trip a GFCI. – supercat Jul 10 at 21:46
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You have a receptacle with no ground or I believe that to be the case. The GFCI breaker doesn’t use or need the ground the test circuit creates an imbalance in the hot / neutral and the circuit trips so your breaker is good. I believe your ground is open and on the plug in testers a resistor is connected hot to ground this creates an imbalance but an open ground it won’t trip. Since your tester works on another circuit the open ground is all that can be wrong.

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  • It should be pointed out also that the only VALID test of a GFCI device is the test button on the device itself. The separate GFCI testers are for convenience only. The fact that they can be fooled is exactly why. – JRaef Jul 9 at 19:52
  • @jraef , not sure I see your point I have been required to verify & record the trip point with an external tester for verifications in a medical facility, not the internal test, this is not fooling but creating an intentional fault 5ma for personal protection and 30-100ma depending on the machine for equipment protection. – Ed Beal Jul 9 at 20:13
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Assuming that the tester is showing a good ground (good ground light is on), you may have a bootleg ground on the outlet. That is, the outlet ground is connected to neutral, not ground. The tester tries to trip the GFCI by connecting hot to ground through a resistor. In this case, because the resistor connects to neutral instead of ground, the GFCI cannot detect it.

The bootleg ground is dangerous because if the neutral wire were to fail, the ground pin would become energized through the device plugged in. If there is no actual ground in the switch box, you should disconnect the ground pin and label the outlet “protected by GFCI”.

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Besides wrong wiring, i.e. a connection between Neutral and Ground downstream of the panel GFCI, there is some likelihood for another reason, as already mentioned in an comment above: The GFCI tester creates a too small imbalance current.

The breaker panel GFCI is most likely only sensitive to a bigger current then 5mA, since the capacitive current between long wires could already create some mA imbalance current without any device plugged into the protected outlets.

In many countries, breaker panel GFCIs are of the type 30mA.

A GFCI tester made for outlet GFCIs would only produce 5mA, which would trip an outlet GFCI, but not a panel GFCI.

A panel GFCI with a threshold of only 5mA would most likely cause many trippings, since some mA can easily flow through earth via plugged-in devices with huge grounded metal cases, especially in high humidity locations, thus creating an imbalance in the GFCI.

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