Second opinion on static

[zFox]

In many places that I read,  and videos that I watch,  people have said that you should have your power supply plugged into a 3 prong outlet,  and set the switch on the back to 0 to stop any current.  Then touch the case,  powersupply, or anything metal often to discharge yourself,  and static will go into the ground.

 

Someone on another forum told me this is a huge safety hazard,  and I am going to post it below to get a second opinion because I am conflicted.

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 "   zFox said:
    Maybe I am misunderstanding something, but I read in multiple places that when you are building, or working on your pc, you should have the 3 prong plunged into the wall outlet, and set the back of your power supply to 0, so any static electricity goes into the ground."

 

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That's a misunderstanding and presents very real safety hazards since you shouldn't work on anything that has wall outlet voltage applied (especially if you lack thorough understanding of how it all functions and interconnects). You don't have to ground charges, you only have to neutralize charges: that is making everything of an equal potential.

That's what touching the case does, it makes your body the same potential as the case (and everything inside of it). And when you hold the bag with the part any charge on the bag (and therefore the part inside it) is also neutralized to the same potential as your body and the case. So it's now safe to reach inside and pull the part out to fit inside the case.

What's really, really bad is to neutralize parts with a super-quick 'shock' kind of discharge: the one where you get zapped. That's why the bag is important: it allows charges to slowly neutralize (several dozens of milliseconds vs. nanoseconds) instead of super fast with a 'zap'.
 

 

[Firewrath9]

how is it hazardous to touch a psu that is grounded?

Touching the case works becuase the case touches the PSU metal to metal, and the PSU outer shell is connected to the ground line.

[Jurrunio]

31 minutes ago, zFox said:

You don't have to ground charges, you only have to neutralize charges: that is making everything of an equal potential.

so far physicists haven't discovered anything of a "negative electron" that can cancel out a charge from say, the voltage of a wall outlet. In other words, the only way to stop electrons from flowing into you is to give it an easier way out (because the less energy way is always chosen). Your body has higher resistance than a grounded wire, that's why if a household item is grounded, you can touch it as much as you want (as long as it's not dangerous in other ways). This stops being safe at uber high voltages, but unless you're in a power station or get hit by a lightning bolt there's no way you can get such voltages and sustain it long enough to hurt you.

 

31 minutes ago, zFox said:

people have said that you should have your power supply plugged into a 3 prong outlet,  and set the switch on the back to 0 to stop any current.  Then touch the case,  powersupply, or anything metal often to discharge yourself,  and static will go into the ground.

If the PSU is plugged in, you don't have to turn anything off either. In fact if I touch the PCB of my desktop when it's running, I'm infinitely more probable to burn myself than shock myself with electricity.