As a Home Inspector for All-Star the most exciting part of the home evaluation for me is the Electrical System. Frequently, I find myself educating folks on the purpose of Ground Fault Circuit Interrupters (GFCI or GFI). GFI's are smart sensing electric devices designed to "trip" in as little as 1/40 of a second when the intended path of electricity is grounded. These simple devices are an integral part of your home's electrical system, are easy to install, and save lives by limiting the duration of an electrical fault. However, my experience has shown me that they are frequently installed incorrectly. Many a handyman or homeowner understands what a GFI reset outlet is and how to reset it, but is not aware of the need to have the device properly installed and located at the most upstream outlet on that particular circuit.
GFI's can be a breaker in the electrical panel with a red reset button located on the breaker, or an electrical outlet with a red/black/white reset button at the most upstream location (1st outlet on the circuit).
Here's an example of a faulty GFI circuit that I found recently which emphasizes the need proper installation. The electrical panel was located within the interior of the garage and contained a GFI breaker with the reset button. The automatic garage door opener and the two baths in the house were wired into that same GFI breaker. When testing/tripping the bath circuit, we quickly learned the GFI reset was in the garage electrical panel. The home did not have a personnel entrance to the garage other than the garage door itself. With the GFI breaker tripped, the automatic garage door opener would cease to function. As such, we were unable to access the electrical panel to reset the breaker! The bath outlet reset buttons were useless because they were not the most upstream outlets on the circuit and were totally unnecessary. GFI protection was still being provided at the bath outlets, but installation was incorrect because a 'trip' would disable the garage door. If the garage door was in the closed position, there was no way to get to the electrical panel. All this could've been avoided had the automatic garage door opener not been wired into a GFI circuit.
In short, GFI's are a great safety invention if installed properly. Remember, GFI's are required at any outlet within 6 feet of water. Currently, this means Kitchens, Baths, Laundry, Basements, and Garages. Also, it's okay to have a non-GFI outlet at these locations as long as it's designated as such.