Re: Human electrical resistance
For an example of what we require in the healthcare setting (which is regulated by 10,000 organizations!) - main concern is that any stray current does not affect patient in critical area - i.e. induce fibrillation or other nasty stuff:
From our Electrical Safety Manual (req'd of all Healthcare Facilities by JCAHO)
Portable medical equipment shall have a leakage current which does not exeed 300mA when mesaured with the ground broken, and/or on or off. The resistance to ground shall not exeed 0.5 Ohm
For equipment with patient leads - the maximum allowable current between the leads and ground is 100mA, between leads, 50mA
If the leads are attached to the heart, the leads to ground shall not exceed 10 microAmps, with ground open 50 microAmps
Same between heart leads
Lastly, in an isolation test, the device shall not allow more than 50 microAmps with line voltage applied between the lead and ground
So, what I've learned is that a little bit of current can go a long way to hurting someone....