Electrical Safety

• Threshold of perception: The minimal current that an individual can detect. For AC (with wet hands) can be as small as 0.5 mA at 60 Hz. For DC, 2 ~10 mA
• Let-go current: The maximal current at which the subject can voluntarily withdraw. 6 ~ 100 mA, at which involuntary muscle contractions, reflex withdrawals, secondary physical effects (falling, hitting head) may also occur
• Respiratory Paralysis / Pain / Fatigue At as low as 20 mA, involuntary contractions of
  respiratory muscles can cause asphyxiation / respiratory arrest, if the current is not interrupted. Strong involuntary contraction of other muscles can cause pain and fatigue
• Ventricular fibrillation 75 ~ 400 mA can cause heart muscles to contract uncontrollably, altering the normal propagation of the electrical activity of the heart. HR can raise up to 300 bpm, rapid, disorganized and too high to pump any meaningful amount of blood  ventricular fibrillation. Normal rhythm can only return using a defibrillator
• Sustained myocardial contraction / Burns and physical injury At 1 ~6 A, the
  entire heart muscle contracts and heart stops beating. This will not cause irreversible tissue damage, however, as normal rhythm will return once the current is removed. At or after 10A, however, burns can occur, particularly at points of entry and exit.

Objective

To ensure that Patients or care givers never Serve as a Current Path due to faulty Insulation, earthing or equipment malfunction.