grounding hook was Re: [TCML] Cap Discharge Questions

[jimlux]

By the way, the real function of the grounding hook is to make sure that 
the potential STAYS at ground, even if something happens (like a 
boneheaded bystander says, "what does this switch do?" and turns on the 
power supply or plugs it in).  You attach it before working on the 
circuit, and then remove it when you're done.  You'd rather blow a fuse 
from having the output short circuited than turn yourself in to a crispy 
critter.

Also, never underestimate the chances of someone plugging the wrong plug 
into the wrong socket. I've done it, fortunately without severely 
injuring or killing anyone, but it was a near thing  (big three phase 
motor controller with same style plug/receptacle on input and output, 
and I plugged motor directly into line, rather than controller). TC's 
tend to get run in darker places and there's often a pile of cords and 
cables.  Someone is working on something else, thinks they are plugging 
in their gear, and plugs in yours by accident.