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So I tried a gfci tester device on a non-gfci outlet without thinking too much over it. Why, you ask? Well, I guess because I am an idiot. As I pressed the test button, half the house lost power. The breaker tripped, but when I put the breaker back to the "on" position, there is still no power. What did I do?

My understanding was that pressing the gfci test button when the device is plugged into a non-gfci would be a non-event, since very little current would actually flow. And yet, here we are.

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    Can you upload a picture of the breaker panel and indicate which breaker(s) tripped? – manassehkatz-Moving 2 Codidact Nov 1 '20 at 6:41
  • Can you post photos of the breaker panel please? Which breakers correspond to the half of the house that lost power? – ThreePhaseEel Nov 1 '20 at 17:05
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My understanding was that pressing the gfci test button when the device is plugged into a non-gfci would be a non-event, since very little current would actually flow. And yet, here we are.

Correlation is not causality.

Your understanding is correct, and the power loss was due to something else entirely.

My money's on "It tripped a GFCI that you don't know about".

I bet it tripped the breaker because it's a GFCI breaker (those have Test buttons)... And I have a feeling it's in a subpanel, which is fed from another GFCI breaker. So now you need to hunt that down.

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    Turns out that my interpretation of the events was incorrect, and your money wins. I was confused because the two GFCIs that I knew about were in the bathrooms. But there was a third one in the master bedroom that I missed completely, because it was hidden and the colors of the reset and test were the same as the rest (they are, as we know, usually red and black respectively). – filmil Nov 2 '20 at 7:10
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If your GFCI tester was well made and functioning properly, you were right - it would draw so little current it wouldn't create any dangerous situation, and it certainly wouldn't draw enough current to overload any wires or to trip any breakers.

GFCI protection is supposed to trip with 4-6ma of current imbalance. A good tester would test by creating a leak / imbalance of just 6ma - just enough to trip the GFCI protection. It also would be made so that it was safe if it was inadvertently plugged into a circuit with no GFCI protection present, or non-functioning GFCI protection - after all, it's a tester, that happens when you're testing.

If it's junk, or even if it was high quality but it's broken, it's possible it may have shorted hot to ground without any resistor to limit the current to 6ma. That would trip a breaker, hopefully the branch circuit breaker, but it could also trip a main breaker in a panel or a breaker feeding a subpanel.

If it was the main breaker for the whole house, and it was functioning properly, tripping the breaker would shut off everything, not half the house. A tripped breaker feeding a subpanel is likely with half your power off.

Locate all your panels, look for a tripped subpanel feeder, switch it off and back on.

If it keeps tripping, don't keep resetting it! Call an electrician and get the issue resolved. It's always possible there was some coincidence or something unusual happened.

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    In the event that the tester was garbage and shorted out your circuit, there could be problems caused in another part of the circuit. A poor connection may have melted and fused together, like a poorly done backstab or loose wiring that was barely touching – Nelson Nov 2 '20 at 8:07

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