[Kevin Sevcik]

It appears I'm now expanding on the above points because I write too much. Nevertheless...

Actually, that rule explains the reasoning a rather lot more than most others. I think it's primarily in place to prevent teams from foolishly trying to save weight by using the robot frame as a current return. Your summary of that standard sounds very much like it applies to robots connected to wall outlets, as opposed to our DC battery powered robots.

In the case of equipment connected to wall outlets, it certainly makes sense to electrically ground the chassis and prove there's an adequate current path to ground from any exposed metal. If the chassis weren't grounded, or some part didn't have an adequate path to ground, a live wire touching that part wouldn't pop any fuses. That would leave that part at some significant potential relative to ground, and anyone touching it could be shocked. But this is only possible because the power supplied to the machine is quite literally referenced to the ground you're standing on, and people are relatively low resistance sacks of salt water.

In our battery powered robots, this isn't the case. The battery is floating relative to ground, so you could touch, grab, caress, or lick the positive terminal (or anything connected to it) and not feel a thing. Provided that you AREN'T touching anything connected to the negative terminal. Since you can only be shocked by touching the positive and negative terminals at the same time, your robot only becomes dangerous if there's both a loose hot wire touching metal and a loose return wire touching metal. If we started connecting our frames to the negative battery terminal, we'd actually be increasing the likelihood of getting shocked because we'd be providing much more convenient return paths if a hot wire were to come loose. At which point we'd then have to either ignore the increased risk or go through a similar qualifying procedure to show that all parts of the robot have a good path back to the negative terminal, etc. So I think the reasoning it that it's easier for teams to keep everything isolated from the frame, and it's easier for inspectors to determine everything's isolated from the frame. As opposed to making sure everything on the robot has an adequate path back to the negative terminal.