The effects of milliamp 60 Hz current flow through a person were first established by Charles Dalziel, who most importantly determined that 99.5% of the population is able to let go of a conductor sourcing 6 mA or less. Tests revealed that on average, perception of current sets in at around 1.1 mA for men, and 0.6 mA for women, pain is first experienced at 9 mA and 6 mA (men and women), and inability to let go at 16 mA and 10.5 mA [1]. Based on this data, current UL standards require "shock prevention", a guarantee that the smallest current which results in the GFCI taking action is "not below 4 mA, and not above 6 mA". In order words, the tripping threshold is set at 5 mA and the system must have milliamp resolution. Shock prevention implies very little possibility of a person becoming 'stuck' on a line, unable to let go. Elsewhere, in places like Europe, the tripping threshold is concerned only with electrocution, and so the threshold is relaxed to 30 mA and higher [2]. This is acceptable, as prolonged current flow at lower levels decreases the body impedance, which in turn increases the fault past the 30 mA threshold. Kouwenhoven and Milnor state that currents 50 mA and less "usually have no serious results, though they may be very painful and may result in temporary loss of consciousness" [3].