You are standing barefoot on a wet concrete floor. Which points are safe to touch (i.e. non-lethal) and why?
A. Dangerous. 120 V between you and ground.
B. Dangerous. 1KΩ resistor reduces current to a maximum of I = V/R = 120 ma, which is still a very dangerous current.
C. Safe. 1MΩ resistor limits current to a maximum of 120 μA, which is not detectable.
D. Dangerous. Voltage divider reduces voltage to 120 × (80 + 10)/(10 + 80 + 10) = 108 V, which is very dangerous.
E. Relatively safe. Voltage divider reduces voltage to 120 × 10/(10 + 80 + 10) = 12 V, which can shock, but which is not lethal.
F. Safe. The isolation transformer cannot provide a complete circuit to ground.
G. Safe. Same as F.
H. Safe. Ground potential.
I. Dangerous. The impedance of the 10µF capacitor is 1/jωC = 1/(j2π60 × 10 × 10-6) = -j265Ω. This has the potential to reduce the current to I = V/Z = 120/265 = 453 ma. This is a dangerous current.
Note! It is never safe or smart to touch any part of a live AC circuit.