[Mike AA]

I believe what you are looking at with the UL1740 is "grounding". Usually as a whole a metal machine in house or business is supplied by a power source that is only protected by its protection device, a breaker or fuse box and if the ungrounded conductor touches a grounded or grounding conductor or the metal frame without a load this will cause the protection device to break.

With robotics we have breakers on every positive wire that leaves the fuse block and the other end is connected to our speed controller then to a motor. Electric motors are designed where the case of the motor is isolated from the conductors and by isolating the robot we also don't have any risk of someone touching the frame and the controller or the frame and becoming the path to a load and having a heart condition or a weird anomoly where the brushes of the motor have a failure and touch the motor casing.


Why is a AA size battery covered in paper or plastic? To keep the sides isolated from simultaneous contact.
So why do we isolate? Just because.

-Mike AA