Originally Posted by BigTJohn
Concerning outlets - GFCI's are usually near any water or in the outside compartments - I have one in the outside water convenience center, who know why, seems like a dumb place to have an outlet - and the connections on every outlet should be checked for tightness, probably once a year or so. Afterall, hauling these things around at 60 or MPH is like a constant Richter Scale 4.7 for each trip. Of course that goes for any mechanical connection be it electrical, water, or physical.
GROUND FAULT CURRENT INTERRUPTER
Basically water and electricity mixed will easily kill a person.
I won't go into electrical theory but take my word for it.
The GFCI outlet will quickly sense a resistive electrical current path to ground and shut down much quicker than a circuit breaker. A hair large hair dryer will trip it sometimes because the heating elements slowly heat up which makes the GFCI that someone or thing is making a direct short to ground. This is a variable resistive load.
You will always find GFCI outlet attached to outside outlets and any where water is located. This is to save a person from electric shock when you make contact to water which is also a source to ground which in turn makes a electrical direct short.
This is only if a body/ human makes contact to a energized conductor meaning the black or red wire in the outlet.
It can also happen if you touch a damaged metal toaster case, etc.
Hope this give you some basic idea what they are used to prevent.
Here is a great link that better describes it than I. Oh it has pictures also.