Can static electricity damage a computer when inside a case?

Thread Starter

Taylor Moffitt

Joined Dec 19, 2015
7
This is another on of those questions of mine that I couldn't find any answer to online, even after searching for several hours. I know that when a computer is plugged into the wall, the case becomes grounded. Therefore you cannot damage anything inside it with static. However, if I where to have my computer unplugged and if I picked it up to move it elsewhere while having a large amount of static in my body, couldn't I damage any components inside of the computer by shocking the case? After all, it is metal...

Or does a computer's case act as a "Faraday Cage" even when unplugged? If so, how is this possible?

Also, this may sound stupid but one of the reasons I'm asking this is because I want to install an SSD but do not have a mounting bracket. I want to know if just throwing the SSD inside the case would be a good idea since mounting brackets have little standoffs on them. Just wanna make sure that its okay to have the whole SSD in contact with the metal of the case, maybe exposing it to static when the case is not grounded.
 

cmartinez

Joined Jan 17, 2007
6,674
Or does a computer's case act as a "Faraday Cage" even when unplugged? If so, how is this possible?
Yes, it pretty much does. Whatever electricity travels through the computer, it will follow the path of least resistance, and hence will remain on the outside of the metallic case while it's discharching. Protecting the components inside.
Static electricity builds up the most on non-conductive materials. That's why anti-static plastic bags (the dark gray ones, in which semiconductors are usually stored) are partially conductive. To minimize static buildup and prevent electricity from following a path inside the bag while it discharges.
 

Thread Starter

Taylor Moffitt

Joined Dec 19, 2015
7
Yes, it pretty much does. Whatever electricity travels through the computer, it will follow the path of least resistance, and hence will remain on the outside of the metallic case while it's discharching. Protecting the components inside.
Static electricity builds up the most on non-conductive materials. That's why anti-static plastic bags (the dark gray ones, in which semiconductors are usually stored) are partially conductive. To minimize static buildup and prevent electricity from following a path inside the bag while it discharges.
So does this mean that connecting yourself to the case to equalize voltage between you and the system your working on to prevent damage doesn't work? Many people suggest doing this but if static cant flow all the way through the case then I don't see how this would be an effective method of preventing damage from ESD.
 

crutschow

Joined Mar 14, 2008
24,116
Touching a conductive case means that the voltage will be equalized between you and the case, and thus if you touch anything inside the case that can be no static discharge since everything is at the same potential.
Preventing static damage doesn't mean everything has to be at ground potential, it just means everything has to be at the same potential.
 

MikeML

Joined Oct 2, 2009
5,444
What is an SSD?

Ask yourself this: How does an ungrounded, slightly-conductive plastic bag protect the IC chip inside the bag if your body is charged to 10KV and you touch the bag?
 

MaxHeadRoom

Joined Jul 18, 2013
19,742
. However, if I where to have my computer unplugged and if I picked it up to move it elsewhere while having a large amount of static in my body, couldn't I damage any components inside of the computer by shocking the case? After all, it is metal...
.
It should be minimized by the fact the MB P.S. ground or Common is also connected to the case, which when plugged in is also earth ground.
Max.
 

Thread Starter

Taylor Moffitt

Joined Dec 19, 2015
7
Touching a conductive case means that the voltage will be equalized between you and the case, and thus if you touch anything inside the case that can be no static discharge since everything is at the same potential.
Preventing static damage doesn't mean everything has to be at ground potential, it just means everything has to be at the same potential.
Yes but how is this not as bad as directly touching the components inside of the case? It would equalize charges but damage it while doing so. Is it because the static evenly spreads throughout the case rather than giving off a charge at one single point on a component?
 

crutschow

Joined Mar 14, 2008
24,116
Yes but how is this not as bad as directly touching the components inside of the case? It would equalize charges but damage it while doing so. Is it because the static evenly spreads throughout the case rather than giving off a charge at one single point on a component?
Yes. It's the discharge directly through any sensitive components that does the damage.
 

#12

Joined Nov 30, 2010
18,182
Touching an individual component allows the static charge exactly one path to equalize with the case and the rest of the computer...through the one component you touched. Touching the case first equalizes everything at the same time...the current path is distributed and diminished in hundreds or thousands of parallel paths, several of them designed to do exactly that...protect against static discharge.

If you try really hard, you can touch one pin of a connector, like the video output or a usb port. Don't try that hard, please.
 

RichardO

Joined May 4, 2013
2,271
Even though you did not ask this...

You can damage a computer that is in an unopened case by touching the contacts of a connector or cable that is plugged into the computer. This is because the conductors of the connector "reach" into the computer. Manufacturers go to some trouble to prevent damage this way but it can still happen.
 

WBahn

Joined Mar 31, 2012
25,107
This is another on of those questions of mine that I couldn't find any answer to online, even after searching for several hours. I know that when a computer is plugged into the wall, the case becomes grounded. Therefore you cannot damage anything inside it with static.
And people that firmly believe this often end up wondering why their computer doesn't work anymore.

There are LOTs of way to breach a leaky conductive shell, such a computer case, and get a static discharge where they can damage things. In fact, a computer in which this was impossible won't be very useful to us. The prime pathway is via signal connections to the outside world.
 

WBahn

Joined Mar 31, 2012
25,107
Aaarrrg! If I see this phrase one more time on this site, my head is going to explode!
Well, you could always go to another site... where your head would explode just as quickly. :D

But I know what you mean, and I know that lots of people can't grasp that this is a qualitative description only and generally only meaningful when talking about paths having at least an order of magnitude difference between their resistance. Thus they think that if you have a 1000 Ω path in parallel with a 1001 Ω path that 100% of the current will go down the 1000 Ω path since it is the "least" resistance.

But, people ARE going to continue using that phrase, both in places where it has meaning and where it doesn't.
 

cmartinez

Joined Jan 17, 2007
6,674
But, people ARE going to continue using that phrase, both in places where it has meaning and where it doesn't.
I agree, and I understand @joeyd999 's frustration... it's just that I feel that a complex problem should first be explained in very simple terms to the uninitiated before taking them into the deep... otherwise the main, important point would most likely be lost, or would take much longer to sink in.
 

crutschow

Joined Mar 14, 2008
24,116
Aaarrrg! If I see this phrase one more time on this site, my head is going to explode!
I know what you mean.
Not only is it trite and inaccuate, it's misused. It originally referred to human behavior, not electrical circuits.
Obviously current follows all the various paths available with the current division inversely proportional to the path resistance.
 

joeyd999

Joined Jun 6, 2011
4,291
I agree, and I understand @joeyd999 's frustration... it's just that I feel that a complex problem should first be explained in very simple terms to the uninitiated before taking them into the deep... otherwise the main, important point would most likely be lost, or would take much longer to sink in.
So....mislead them first?

When training dogs, you quickly learn that it is far easier to teach new good habits than to break bad old ones.
 

#12

Joined Nov 30, 2010
18,182
So....mislead them first?
Teach them the basics first, then the exceptions.
A computer case is basically a Faraday cage...but it has exceptions, connectors to the outside world and you can use them to abuse the protection that was intended to help you.
 
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