1. ECE 201 Circuit Theory 11 Electrical Safety Example A person accidentally grabs conductors connected to each end of a DC voltage source in each hand. –What is the minimum source voltage that can produce electrical shock sufficient to cause paralysis, preventing the person from letting go of the conductors? –Assume that the resistance of the arm is 400Ω, the trunk is 50Ω, and the leg is 200Ω.

2. ECE 201 Circuit Theory 12 + V -

3. ECE 201 Circuit Theory 13 + V - Current flows through the arms R A = 400 Ω

4. ECE 201 Circuit Theory 14 Safety Example continued From Table 2.1, the minimum current for muscle paralysis is 50 mA.

5. ECE 201 Circuit Theory 15 Safety Example continued Is there a significant risk of this type of accident occurring while servicing a personal computer, which typically has 5V and 12V sources?

6. ECE 201 Circuit Theory 16 Safety Example continued Compute the maximum current that can be drawn from the computer power supply. This current will cause a shock, but will not cause muscle paralysis.