GFCI tester

Using a standard GFCI outlet tester a GFCI will not trip. It will trip with the test button. Why?

Jim Campbell

A three light tester will not trip an ungrounded device.

The only recognized test is the built-in test button.

  1. Tester broken/inop
  2. Outlet not grounded
  3. Doesn’t really matter. The Test Button is the only Manufacturer Approved testing method!

I agree about the testing method but wouldn’t you want to know if the receptacle was ungrounded?

When you press the GFCI test button on a 3 light tester it connects the hot to ground through a 15k ( or there about) ohm resistor. This diverts about 8 milliamps of current to ground instead of returning that current on the neutral under these circumstances the GFCI detects a ground fault and trips. I believe the minimum current differential between the hot and neutral that trips a GFCI is 5 milliamps.

No ground in the receptacle no GFCI trip or test takes place.

There was a huge discussion about the potential safety risks of ungrounded GFCI outlets a while back. Are we going there again?

Nope! Not me mon!! :mrgreen:

Write it up PERIOD!

Write what up? It works with the test button, as required (and approved) my the manufacturer. Manufacturer trumps all.

Would you not note that if the receptacle was ungrounded or that the ground could not be verified?

#-oOh no!!!

Inform your client the GFI needs a sticker to identify No Equipment Ground.


De’ja’ Vu, huh! :mrgreen:

Yes, but has no effect on the operability of the receptacle to perform it’s design function.

Was this an older home?

My point was that a standard ungrounded receptacle is typically called out. Why would this be any different? It seemed like someone was saying it would not be noted just because it functioned as designed.

I am aware that the ground is not needed for proper operation.


I understand your point, and do not question your knowledge of electrical. I’m sure your knowledge far exceeds my own. With that being said, my comments were more for the benefit of ‘less knowledgeable’ members who may not be as aware of GFCI function.

I operate in the land of “ungrounded systems”. Ungrounded systems are not a material defect. I do not “call out” ungrounded systems… but, I DO make note of them and discuss the scenario with my clients… the same as with ungrounded GFCI’s.

My apologies for any confusion I may have created.

and hopefully, everyone understood that an “ungrounded” GFCI device is not necessarily “unsafe.”

The question I have is, when the GFCI tripped with it’s internal test button, did it de-energize the receptacle? If so, it’s functional.

The OP never stated that it had an open ground, but if so, on a two-wire system, the GFCI device should include a label stating that it does not include the egc. If it’s a three-wire system, it should be deferred to an electrician to establish the grounding connection.

Correct me if I’m wrong but the OP should have been able to see from his tester if the receptacle outlet was ungrounded or had an open ground as only 1 light would have turned on.
If only 1 light was on, then the tester would not have tripped the GFCI device.