Here is some information from a WEB site ... Not saying it's the answer to your question but something to look at..
What is a GFI?
A GFI, or ground fault circuit interrupter, is an automatic device that offers personal protection against electrical shock. They are installed in areas where known electrical shock hazards exist... outdoor outlets and fixtures, swimming pools, saunas and hot tubs, outlets in kitchens, basements, bathrooms, and garages. Wherever there is the potential for contact between a person and an electrical appliance in or near moisture, water, or water pipes, a GFI should be protecting the circuit... and you!
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How does a GFI work?
Inside of a GFI is a sensor that detects changes in current to the appliance by comparing the current flowing to the appliance and the current flowing from the appliance. A drop off in the current equivalent to about 5 milliamperes turns off all power by tripping a relay within the GFI within a few hundredths of a second. You might hardly even feel the shock, it happens so quickly!
However, there is still a danger since 5 milliamperes can cause a "jerk reflex" or spasm in the muscles. This is not too bad if you are standing on the ground but potentially dangerous if you are on a ladder or roof!
GFI's can be reset to restore power to the affected circuit. If the problem still exists, though, the GFI will not reset.
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Are there different types of GFIs?
The three basic types used in homes are the GFI outlet, the GFI circuit breaker and the portable GFI. All perform the same function each has different applications and limitations.
The GFI outlet (shown above) is intended as a replacement for a standard electrical outlet. It protects any appliance plugged into it, and can also be wired to protect other outlets that are connected to it.
IMPORTANT: A GFI outlet is not difficult to install, but the instructions for installation and testing must be followed precisely to insure the GFI works properly!!
The GFI circuit breaker controls an entire circuit, and is installed as a replacement for a circuit breaker on your home's main circuit board. Some homes are wired so that all bathrooms or all outdoor fixtures are on the same circuit. Rather than install multiple GFI outlets, one GFI circuit breaker can protect the entire circuit.
If you decide that the GFI circuit breaker is your best option, you must purchase one that is a match for your main electrical panel. If you have an older panel that utilizes fuses, you cannot use a GFI circuit breaker and must use GFI outlets instead.
Resetting a GFI circuit breaker is a little different than resetting an outlet-type GFI. There is no "reset" switch. Instead, the GFI breaker is reset by first switching the breaker to the full "off" position, then to the full "on" position to restore power.
There is also a portable GFI that is often used by contractors. They are discussed in another part of this article. Click HERE to go there now!
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How do you test a GFI?
All GFIs, whether local or central, have two testing-related buttons on them. One button is appropriately labeled TEST, and one is labeled RESET. Turn on an appliance or light fixture connected to the GFI. Press the TEST button, and the appliance should immediately turn off. If it does not, either the GFI is miswired, there is a problem with other wiring in the same circuit, or the GFI has malfunctioned and should be replaced. Pressing the RESET button will restore power to the appliance or circuit.
Conversely, if you have a GFI that has tripped and will not reset, you may have a wiring short in the circuit, a defective appliance on the circuit, or the GFI itself has become defective.
The easiest way to troubleshoot a GFI is to obtain a GFI tester, available at most hardware stores. It plugs into the GFI outlet, and will supply you with a "snapshot" of your connections, indicating wiring problems and/or the condition of the GFI. Another way to troubleshoot is to simply purchase a new GFI and install it.
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