Just a little trivia here. We had a rep from UL at a meeting and GFCI's was the main topic.
GFCI protection for personnel is set to trip between 4ma and 6ma. An interesting thing mentioned was that the speed with which they operate depends upon the level of the fault. A low threshold 4ma fault could take up to something like 4.8 seconds to trip depending upon the sensitivity of the particular unit.
Bill
