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Windows 7: Grounding a PC


31 Oct 2010   #1

 
Grounding a PC

For some reason, my tower is highly susceptible to static discharge. In particular, whenever my 9 yr old daughter stands within 2 feet of my PC, it will instantly reboot!

This is not fun.

Any thoughts on improving grounding on the box? It runs on a dedicated electric circuit, three prong plugs yada yada.

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31 Oct 2010   #2

Windows 8.1 Pro w/Media Center 64bit, Windows 7 HP 64bit
 
 

You daughter is eating too many "apples"

If you have carpet try some anti static spray. Also you can check the ground on the receptacle.

Jim
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31 Oct 2010   #3
Microsoft MVP

64-bit Windows 8.1 Enterprise
 
 

Hello Roger,

You might see if one of those computer static mats under the tower may be able to help.

Hope this helps,
Shawn
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31 Oct 2010   #4
bkl

Windows 7 Pro x64
 
 

Quote   Quote: Originally Posted by Phone Man View Post
Also you can check the ground on the receptacle.
... with one of these or equivalent: Amazon.com: GE 50542 Receptacle Tester, 3-Wire Light Improper Wiring Indicator: Home Improvement: Reviews, Prices & more

To find out if the ground is open you need to pull some current through it like those testers do. Have you tried that yet? In addition to open ground it will check for hot and neutral being reversed.

You said its a dedicated circuit, so you have probably had an electrician check the house's ground to make sure it is really grounded? A surprising number of panels wind up either being "grounded" to something that isn't actually grounded or have corroded connections on the ground wire/rod. The gold standard here to make absolutely certain you have a good ground is to have the electrician pound in a fresh ground rod with new hardware and run an appropriately sized ground wire back to the panel.

Also something fun to look into if your power is coming from a drop cable from an electric pole - I've seen this have weird effects before - go out to the pole and see if a copper-thief has cut the solid ground wire running down the pole into the ground. Don't touch that wire if it is cut! There could be enough voltage on it to give an unpleasant surprise.

I'm an electrical engineer - I'm curious what would cause a PC to do that. I've worked with a lot of PC installations but I've never run into that before. Maybe I've just been lucky!
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31 Oct 2010   #5

 

The office has cork flooring - no carpet. I will check the ground, but as said, its a dedicated circuit and a pretty new house ... maybe I should tag an extra grounding cable from the case to a known ground?
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31 Oct 2010   #6

 

Quote   Quote: Originally Posted by bkl View Post

... with one of these or equivalent: Amazon.com: GE 50542 Receptacle Tester,

I'm an electrical engineer. I'm curious what would cause a PC to do that. I've worked with a lot of PC installations but I've never run into that before. Maybe I've just been lucky!
Thanks, bkl. I do have one of those somewhere here, and I'll do that. My daughter is pretty high-test, so you might just have been lucky not to have been subject to her "aura".

It has happened enough times that she is banned from the office - she has blanked my MBR too many times for it to be amusing any more.
My System SpecsSystem Spec
31 Oct 2010   #7

Win7 Enterprise, Win7 x86 (Ult 7600), Win7 x64 Ult 7600, TechNet RTM on AMD x64 (2.8Ghz)
 
 

Sometimes in the fall & winter, I have to spray a fine mist of Downey fabric softner on my carpet & rubber floor deskchair mat. I not suggesting spraying her down, but ........


Attached Images
 
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01 Nov 2010   #8
bkl

Windows 7 Pro x64
 
 

That is really interesting about your daughter's static accumulation! There is actually such a thing as a static electricity detector to measure her accumulation. I see some for sale doing a Google. They can be made fairly easily too with a jfet or mosfet transistor and a LED:

Static electricity sensor : DISCRETE SEMICONDUCTOR CIRCUITS

The ground wire on the PC should connect to the case inside the PC's power supply and hence ground the case. But if the electrostatic field was high enough, and close enough to the front of the PC, it may be possible to get a static accumulation through the plastic parts on something like the reset button. But even then I would expect those circuits to be low impedance enough to prevent that from happening.

If I were troubleshooting something like this, and had verified that the wall plug ground was good and the panel ground was good, I would probably remove the PC's power supply next and either dismember it to check the ground connection inside, or simply swap out the supply with another.

If I were testing that wall plug ground I would also use something like a 100watt lightbulb in a lamp that would pull 0.8 amp. Then measure the voltage at the plug with the lamp plugged in (hot to neutral). Then I would run the lamp from hot to ground and do the same voltage test and see how the two compare. Often grounds are daisy chained through the various wall outlets and junction boxes on their way back to the panel. Even with a dedicated circuit it may go through a couple of junction boxes back to the panel. If any of those connections are loose or corroded you will get a bad ground.

Another fun thing that happens, especially with older electrical breaker panels, is the screws loosening up. Something to have your electrician do is to re-tighten all the breaker screws, neutral screws on the bussbar and all the ground screws on that buss bar. And while he/she is in there have them pull the feed breaker or fuse and check the tightness of the setscrews on the large wires feeding the panel. I've seen a nice large arc/spark come out of the feed setscrew on a 100 amp panel that was running at 98 amps (being replaced and upgraded) when that feed wire was moved slightly (loose screw!). Interesting enough that situation had large amounts of noise on the electrical plugs - they had surge supressors everywhere - which all then went away. That loose connection was just sitting there sizzling and creating noise throughout the building.

One other random thought. Try replacing the A/C power cable going from the wall outlet to your PC. The crimps on the ground wire at either end can go bad just like the crimps on the hot and neutral wires can do. But its never noticed since the PC keeps running just fine, at least until something like this comes up.
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01 Nov 2010   #9

Windows 7 Ultimate x64 SP1
 
 

Sounds like your daughter needs to be grounded...not the PC!
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01 Nov 2010   #10

Windows 7 Pro. 64/SP-1
 
 

Do this happen when your daughter gets close to any other electrical appliance. Found a little meter that might help.
Voltage Touch Monitor
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