I have replaced a traditional breaker with dual function AFCI / GFCI breaker hoping to make the outlets up to code (3 prongs with no ground). However, when testing with GFCI tester, outlets with no ground do not trip the breaker (not expected). There is 1 outlet which has its ground connected to water pipe would trip during test (expected). All outlets source from the same breaker.

Any ideas?

  • Is your electrical system grounded to the water pipe? Is the water pipe metal?
    – Ed Beal
    May 8, 2017 at 18:50
  • Yes, copper pipe. But only 1 outlet out of a series of outlets is connected.
    – some user
    May 8, 2017 at 19:08

2 Answers 2


GFCI plug in testers with a trip button won't work without some ground connection. When the test button is depressed it is basically a high resistance leak to the ground pin, with no ground wire connected the test fails.

Specifically this type of device: enter image description here

Additionally: If the outlet is GFCI protected but has no ground it should be marked "GFCI protected No Equipment Ground" with the stickers that came with the device.


If a device only can access hot and neutral, it cannot cause a ground fault. The very nature of a ground fault requires a third path of some kind.

I would run a stretch of wire from an actual grounded point and use that as your third path. You could attach it to the center screw of the outlet under test (genuinely grounding the outlet), and then just use the tester. You could also do a neutral-ground fault test: deenergize the corcuit, pop the receptacle out, tie the ground test lead to neutral, energize the circuit, and if necessary plug in a heater - that should also trip the GFCI since some of the return (neutral) current will take the third path.


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