Wednesday, September 28, 2011
You know those outlets in your bathroom with the red and black buttons in the middle that sometimes need to be reset? Those receptacles are designed to keep you from electrocuting yourself while making toast and taking a bath at the same time.
They are called Ground Fault Circuit Interrupters or “GFCI” for short. The GFCI limits that shock you can receive from the receptacle to 4 milliamps or less, which is not lethal. It might tingle real bad, but it won’t kill you.
Our ninja learns about GFCI receptacles the hard way. He thinks he can electrocute the red ninja by forcing his knife blade into the receptacle, but since it is a GFCI receptacle, it only stuns his foe. And once he shakes off the stun, he proceeds to complete the lesson.
Where in this picture are the red and black buttons on the receptacle? The answer is that they are in another receptacle upstream of this receptacle. One GFCI receptacle can protect multiple standard receptacles on a single circuit. That is why our MEP ninja did not realize that his plan was destined to fail.
Mark Robison, PE
