Following on Paul's last two sentences, look at this situation:
When the tool is working normally, the current flowing will be about 7 Amps. The circuit and its resistance can be shown by this diagram:
When the circuit works normally and 7 Amps is flowing, the touch voltage
on the neutral will be:
(R4 + R6)* 7 Amps = 2.1 Volts. Too low to feel.
(R1 and R2 are so big, compared to R4 and R6, that they can be ignored to simplify the calculation; and R7 and R8 aren't present, cause the tool is working normally, that is, the hot wire hasn't broken loose and touched the grounded metal of the tool body.)
When the hot wire shorts to the tool body, and is not connected to the neutral, the current that flows is 188 Amps and all of a sudden, the person not only gets shocked, but because of the bad conditions (weather, mud, sweat) gets badly shocked
. The circuit becomes this equivalent: