17.2  Assuming a person's body resistance is 400  W and a person can just survive a current time of 20 mAs.  How quickly does a 200 V circuit have to be shut down for a connected person to survive?

17.4  A large machining center runs a routine for rigid tapping.  The threads suddenly start getting torn up during the tapping cycle.  Propose a plan for investigating the problem.  Include all three skill sets in the plan.  Prepare several testing charts and methods.