How do you check a ground fault interrupter?

There is only 2 forms of Ground fault protection. A breaker or a recptacle (stadard plugs and outlets). Both are obvious to the naked eye. A recptacle will have a test and reset button that will turn it on and off. This is a sensor that constantly monitors the diffence of potential between the HOT wire and the grounded conductor . If this gets to and unacceptable limit It will trip. The breaker will have a test and reset button next to the switch. The complicated part is that 1 GFI outlet can protect multiple outlets. When it is hooked up it has an option to Downstream other outlets. Theese outlets are then monitored by the same sensor in parralel with the first. The best way is to push the test button and check for outlets that shut of with the GFI. Code requires a GFI protected outlets to have a sticker on it stating that fact. A breaker wll protect the entire circiut from ground faults provided it is hooked up correctly.