Question - I find it hard to understand how a person can get an electrical shock yet be told the GFCI (ground-fault circuit interrupter) outlet was wired properly. How can that be? Is it legal to install the outlet without a ground? - Anonymous
Answer - The GFCI (ground-fault circuit interrupter) was designed to shut off the flow of electricity through the outlet when a fault is detected. It is set to trip (shut off the electrical flow) whenever a current fluctuation as small as 5 milliamps is detected.Normal breakers and fuses require a short to ground before they trip. A GFCI, however, has an interior circuit that measures the difference in current flow between the hot wire and the neutral wire (not ground wire). When the flow varies by 5 milliamps, the device trips in one-fortieth of a second. It is within that one-fortieth of a second that you may or may not feel a small shock, but you're not dead.
According to the National Electrical Code, it is acceptable to use a GFCI on an ungrounded system. However, there are strict rules for installing these life-saving safety devices on ungrounded systems. Therefore, they should only be installed by a licensed electrician.