A GFCI (Ground Fault Circuit Interrupter) compares the current leaving
(black wire) and returning (white wire) to the device. When the current
differs by 3 mili amp the device is suppose to trip (turn off power to
the load). This circuit dose not know where the leakage current went,
only that it is missing. A GFCI device is only effective for line
(black) to ground (Green or bare) leakage current. If you are in the
circuit (part of the load), current flowing from the black wire through
your body and back to the white wire the GFCI will not trip because 100%
of the current is accounted for. Also if you throw a appliance plugged
into a GFCI into a plastic bath tub full of water, the GFCI will not
trip (Bird on a wire scenario) until a current leakage path to ground is
established. The Test Button places a 3 ma current shunt around the
device and if it is working properly it should trip The current
(amperage) parameters of a GFCI where established because the average
human normally survives a 5 mili amp electric shock. From personal
experience I know you will have absolutely no problem feeling 3 ma of
AC current pulsing through your body. And after the 15 minute
unintentional break you can look at the bright side of things, I won't
have to use my Beck blood electrifier unit today.
