How to ground PC without PSU?

[TomMe]

First, let me apologize for making yet another thread that has to do with ESD. But it seemed to me like the best way to get some needed information. Please don't make this into a discussion about whether or not ESD is real.

People say you should ground a computer case when working inside so that a potentially harmful discharge between person and case can go to ground instead of the computer components (that’s what I understand of it anyway). To do this people recommend leaving the PSU plugged in. But what if you have to swap your PSU? If you disconnect it, the ground is gone and components are more vulnerable to ESD (if I understand it correctly). Would it be a good idea to use a separate wire to ground the case? And could this be used as a full alternative to keeping the PSU plugged in while working inside?

To ground the case I would use a wire like this, attach its ring to the case with a screw at the back and connect its plug to an earth bonding point like this.

But is that really a sound thing to do, is it safe? Can I use both this wire and PSU at the same time (even while the computer is running), or will this create problems? I’m not all that comfortable with strapping a wire to my case.

Regards.

 

[BoogerBomb]

I would think you could just attach a wire to the case and the other end to the screw on the faceplate of a plug as they should be grounded. At least in the past they were.

 

[agent420]

But is that really a sound thing to do, is it safe? Can I use both this wire and PSU at the same time (even while the computer is running), or will this create problems? I’m not all that comfortable with strapping a wire to my case.

Any of those products works fine and is perfectly safe. Ground straps incorporate a current limiting resistor of ~ 1 Meg that prevent dangerous levels of current from flowing, while at the same time proviiding a path for static charges to dissapate. This is probably safer than keeiping your pc psu plugged in, as it completely elimiates dangerous voltages. Also, many motherboards have the 5v standby power running through them even when the pc is off, and it would not be impossible to cause damage by shorting something out.

You can do this yourself with a alligator test lead and a 1M resistor.

I find it slightly amusing that you would be uncomfortable strapping a wire to your case, when you don't even know how that method works... yet working on a system with a plugged in power supply is ok?

I see you are very concerned about all this, so my best suggestion to you would be to invest in an inexpensive ground strap... and you'll never have to worry again


Here's a technical jargon filled whitepaper talking about the whole thing...

 

[TomMe]

This is probably safer than keeiping your pc psu plugged in, as it completely elimiates dangerous voltages. Also, many motherboards have the 5v standby power running through them even when the pc is off, and it would not be impossible to cause damage by shorting something out.

That's what I was thinking too.. Now that you mention it, what about the charge that is left inside the PSU when it is unplugged (which makes it so dangerous to open one), does the motherboard still receive current from this?

I find it slightly amusing that you would be uncomfortable strapping a wire to your case, when you don't even know how that method works... yet working on a system with a plugged in power supply is ok?

That's the very reason I'm not comfortable with it, because I don't know how it all works and what the effects will be. I wish I did. And no I wouldn't feel safe working on a system with a plugged in PSU either, even if it's switched off. I would say, even less safe because of the apparant risk of electrocution.

I see you are very concerned about all this, so my best suggestion to you would be to invest in an inexpensive ground strap... and you'll never have to worry again

Since I've lost that Voodoo card recently due to mysterious reasons, I've never been the same..R.I.P. my friend. Actually I'm about to buy myself an ESD kit, along with a couple of more things. Just wanted to know what to do in case of replacing a PSU.

So can I use the separate wire even when the PC is running? It won't cause any strange things like ground loops? Admitted, I don't exactly know what a ground loop is. In any case, I'll just use the wire only when switching hardware, but I'm still curious.

 

[agent420]

Now that you mention it, what about the charge that is left inside the PSU when it is unplugged (which makes it so dangerous to open one), does the motherboard still receive current from this?

Not really an issue. The residual power in question is used in the switching operation of the psu and not the power supplied to the board.

So can I use the separate wire even when the PC is running? It won't cause any strange things like ground loops? Admitted, I don't exactly know what a ground loop is. In any case, I'll just use the wire only when switching PSUs, but I'm still curious.

No problem at all.

 

[TomMe]

Oh, I was still editing my post when you replied. And then my system crashed..

Thanks for clearing things up agent420.

 

[agent420]

Oh, I was still editing my post when you replied. And then my system crashed..

Could be esd LOL

Really, a ground wrist strap and common sense will go a long way without having to worry about all the technical aspects.

 

[Mohonri]

If you're worried about damaging components in your computer while working on it, all you need to do is make sure that you and the case are electrically connected. That's it. If you work with the PSU plugged in, you simply make sure that both you and the computer are at the same potential with as much other stuff as possible, so it adds some measure of safety.

You don't have to worry about being electrocuted with your PSU plugged in. Here's why:
--The PSU case (the 3.25"x6"x5.5" metal box itself) is grounded anyway. If you look inside, you'll see a hefty green/yellow wire connected to the PSU case.
--If there was any risk of being electrocuted by an intact PSU, there's no way it would pass certification.
--The PSU's ground is connected to your entire chassis. So the risk of electrocution from touching the PSU is no greater than from touching the outside of your case.
--The voltages produced by the PSU (+12V, +5V, etc) are way too low to cause you any damage. (See this article on the topic)