Computers and wall outlets that are not grounded... Problem?

[TechnoPro]

So after a rather fierce lightning storm a few weeks ago, I get a few calls that some client's PCs are acting strangely, or have just died. The common denominator? Cheap surge protectors and/or ungrounded outlets. Now, I've read that surge protectors of all calibers can lose their ability to arrest a surge. So what's the scoop on having ungrounded outlets. I've always believed that the grounding was crucial for protection during electrical surges. What's the real deal? Any expert opinions?

 

[rustynails]

Yes grounds are absolutey essential in order to keep proper protection. You have your hot (typically black) which send current (voltage) down to your pc, and back to ground through your nuetral (typically white). Your pc completing the circuit. Now if an abnormal amount of voltage is detected, the arrest proctector will cut the circuit. However if there is an extreme amount of voltage; this voltage needs to be released through the ground, and if that ground is not there, it will jump ship and continue through the device, in your case, your pc.

 

[TechnoPro]

Originally posted by: rustynails
Yes grounds are absolutey essential in order to keep proper protection. You have your hot (typically black) which send current (voltage) down to your pc, and back to ground through your nuetral (typically white). Your pc completing the circuit. Now if an abnormal amount of voltage is detected, the arrest proctector will cut the circuit. However if there is an extreme amount of voltage; this voltage needs to be released through the ground, and if that ground is not there, it will jump ship and continue through the device, in your case, your pc.

Great explanation, thanks!

So what about a 3-pronged device that plugs directly into the wall? What purpose does the ground serve there?

 

[rustynails]

Grounds are always design for fault protection. So let say your hot for what ever reason becomes disconnected from its typical installation and is making contact with your chasis or your case. If you have a proper ground (in this case the third prong) the voltage will be released and all is good. If not the case becomes engergized and is waiting for a way to reach ground, typically by somebody placing their hands on the steel case and out the bottom of their foot. Remember first and formost ground where put into place to protect us, not the equipment.

Just to put into perspective if you plug two pc into ungrounded outlets and place a voltmeter from one chasis to another you will get 120v, assuming the chasis are not sitting on a grounded surface.

 

[TechnoPro]

Originally posted by: rustynails
Grounds are always design for fault protection. So let say your hot for what ever reason becomes disconnected from its typical installation and is making contact with your chasis or your case. If you have a proper ground (in this case the third prong) the voltage will be released and all is good. If not the case becomes engergized and is waiting for a way to reach ground, typically by somebody placing their hands on the steel case and out the bottom of their foot. Remember first and formost ground where put into place to protect us, not the equipment.

Just to put into perspective if you plug two pc into ungrounded outlets and place a voltmeter from one chasis to another you will get 120v, assuming the chasis are not sitting on a grounded surface.

Where are my manners? Welcome to AnandTech!

I certainly appreciate the refresher. I think I need to do some brushing up on the basics...

 

[JimPhelpsMI]

Hi, The third wire (Green) ground is for operator safety. If the black lead (Hot) should happen to contact the case there will be a dead short and the circuit breaker in the wall will throw. Without the ground the case will become lethal if the op should touch the case and another ground at the same time. Applies to all electrical devices and is required by the electrical code. Also is a help on a lightning hit. Lot's more to this, but maybe this will answer your question.

 

[CrispyFried]

Originally posted by: rustynails

Just to put into perspective if you plug two pc into ungrounded outlets and place a voltmeter from one chasis to another you will get 120v, assuming the chasis are not sitting on a grounded surface.

Huh?

Explain please. You should get zero volts between two chassis even with ungrounded outlets unless theres a serious problem with the PCs.

 

[Zepper]

Dittos Crispy Fried - Besides protecting from wandering line voltages, static electricity can only be bled off via a true earth ground (which the third prong is supposed to provide). Rotating devices like hard drives, tape drives and optical drives generate static charges which need to be bled off.
. Also during storms, high voltages can be induced in the neutral wire so an alternate path to ground is needed.
. Good surge/spike protectors will provide three paths for surges: Hot to Neutral, Hot to Ground and Neutral to Ground.

.bh.

 

[imported_Technomancer]

I'm currently reading a book on laptop repair... this is probably similar to desktops which is why I'm posting, but the author says that proper grounding wires are absolutely crucial because the system checks the voltage of the grounding wire for bit parity checks, among other crucial system checks. I suspect this has severe effects for TCP/IP, ECC memory, and not to mention the other normal system operations. Oh, it also said that even good surge protectors don't protect against this problem.

 

[rustynails]

Originally posted by: rustynails

Just to put into perspective if you plug two pc into ungrounded outlets and place a voltmeter from one chasis to another you will get 120v, assuming the chasis are not sitting on a grounded surface.

Sorry i thought i had explained a cheater way of grounding before i made the above statement. Which is this.

Beacause your nuetral and ground ultimately end up at the same place you can drop the nuetral and terminate to your ground screw also. That being said a few things to keep in mind
1) it is not up to code
2) only do one oulet per circuit, if not, then the aformentioned statement comes into play. (chasis to chasis 120v)
3) it does work. Should a surge be strong enough to trip the arrest, it will discharge out the ground and in this case the nuetral.

However the proper way is to run a ground from your outlet to and outside binding post, typically 1/2 inch copper rod, earth atleast 4 feet into the ground, or what ever your NEC NPFA deems necessary.

Didnt mean to scare anybody. And please kill the power when messing around with electrical

PS. my house was built in 1960, and no grounds. I currently live in one of the highest lightning stuck areas in the country. this time of year its not uncommon for me to come home from work and find all my clocks reset on a daily basis. I currently use the method i described above with a 350 tipplite ups.