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Posted: 2/1/2006 10:16:29 PM EDT
Me and my friend have just moved into an apartment owned by Sniper_Wolfe's grandma and it seems that there is a weird issue in the wiring that my PC is picking up. Whenever I'm messing around with the internals of my case and touch it with a more sensitive patchof skin (face, inside of arms), I can feel a little current arcing from the case to my skin.

I figured it was just a grounding issue with the motherboard on the case so I posted on DFI-Street.com about it and everyone there seemed to think it was an electrical problem with the house. One guy called it a "floating ground." I was just looking for some insight and advice on what I should do about the issue.
Link Posted: 2/1/2006 10:19:11 PM EDT
Why did you take apart your computer and stick your face in it?
Link Posted: 2/1/2006 10:22:02 PM EDT
I was messing with arranging fans for the best airflow over my overclocked CPU and checking resulting changes in temperatures when my cheek was resting on the edge of the case, that's when I felt it and examined a little farther and realized it was electrical in nature. At first it just felt like a little burr on the metal scraping me but later on I also felt it on my arm.
Link Posted: 2/1/2006 10:36:48 PM EDT
You need an outlet tester or a multimeter to check the outlet. Should be able to find one at your local hardware store.
Link Posted: 2/1/2006 10:43:41 PM EDT
[Last Edit: 2/1/2006 11:51:09 PM EDT by blacklisted]
Sounds like a grounding issue. I was working on my computer once and something similar happened. I was laying on my floor with my cheek touching the heater vent on the floor. My other cheek touched my case and I got a horrible shock through my head. This probably has something to do with the metal ductwork touching the ground directly under the house.

Outlet testors say there is a grounding problem and my surge protector says "building wiring fault'. I live in a fairly old house so it has old wiring. I don't worry about it though.

ETA: It was the cheek on my face.
Link Posted: 2/1/2006 10:53:20 PM EDT
Check the voltage between the ground and neutral. I've seen this problem many (more than a dozen!) times. Usually the neutral isn't bonded to ground at the fuse box when this happens.z
Link Posted: 2/1/2006 10:54:50 PM EDT

Originally Posted By blacklisted:
Sounds like a grounding issue. I was working on my computer once and something similar happened. I was laying on my floor with my cheek touching the heater vent on the floor. My other cheak touched my case and I got a horrible shock through my head. This probably has something to do with the metal ductwork touching the ground directly under the house.

Outlet testors say there is a grounding problem and my surge protector says "building wiring fault'. I live in a fairly old house so it has old wiring. I don't worry about it though.





You shocked yourself!
Link Posted: 2/1/2006 11:00:10 PM EDT
I would say your electrical ground wiring path is open circuit.

Do what they say - get a circuit tester and look for open ground lines.

Here's a stunning revelation (at least to me):

The NEC requires a grounding rod to go 8 to 10 feet deep into the earth. No, your cold water pipes do not qualify as your primary ground.

Eight feet minimum, how do they drive that in?????
Link Posted: 2/1/2006 11:05:10 PM EDT

Originally Posted By Mike_Mills:
Eight feet minimum, how do they drive that in?????



With a hammer.
Link Posted: 2/1/2006 11:32:27 PM EDT

Originally Posted By Tim84K10:

Originally Posted By Mike_Mills:
Eight feet minimum, how do they drive that in?????



With a hammer.



It's very simple really. They just throw it into the ground really hard and it goes exactly 8 feet into the ground.

<­BR>


Link Posted: 2/1/2006 11:37:59 PM EDT

Originally Posted By zoom:
Check the voltage between the ground and neutral. I've seen this problem many (more than a dozen!) times. Usually the neutral isn't bonded to ground at the fuse box when this happens.z



B-I-N-G-O
Link Posted: 2/1/2006 11:44:28 PM EDT
You have a grounding problem. It can be fatal if you get zapped just right.
Be careful and get it fixed,perferabley by someone who knows what they are doing.
Link Posted: 2/2/2006 5:49:36 PM EDT

Originally Posted By Tim84K10:

Originally Posted By Mike_Mills:
Eight feet minimum, how do they drive that in?????



With a hammer.



LOL!, I'm sure, but you have to start atop a ladder to hammer on the top of an eight foot pole.
Link Posted: 2/2/2006 7:45:40 PM EDT
If it's a really old house there might not be a ground! Do you have to use an adapter to use your three prong plug?

Bob
Link Posted: 2/2/2006 8:42:36 PM EDT
Nope, nothing like that. Just seems that it's not grounded properly, I'm still waiting on my new heatsink before I pull the board and properly insulate the screws.
Link Posted: 2/2/2006 8:52:07 PM EDT
Fixed this problem before. Customer complains that she gets shocked when she's in the shower and touches the shower head or unloading the dishwasher and touches the latch. Usually find that the grounding/bonding conductor is loose at the ground rod. Neutral has to be bonded to the ground so there's no difference in potential between them. There appears to be and you used your face to bond them together briefly. Check your connection from your panel to your ground rod, if you have one. Was any plumbing done that might have replaced the metal pipe w/ PVC? Alot of systems were grounded to the cold water pipe only. No metal pipe, no ground.
Link Posted: 2/2/2006 8:59:51 PM EDT
It can be even more subtle than a PVC pipe.

If you have galvanized pipes and copper, the two systems will be electrically isolated to prevent galvanic corrosion. It may appear the copper pipes are in contact with the galvanized but there are going to be, should be, non-metallic washers isolating the two metals. No electrical contact = no ground.

P.S. - As I said the NEC does not allow using copper pipes as your ground.

Link Posted: 2/2/2006 9:07:21 PM EDT
Hopefully nobody wired the outlet wrong and mixed up the neutral and active wires.

I've seen felt that before.
Link Posted: 2/14/2006 7:13:44 PM EDT
NEC would allow cold water pipe main ground to be "grandfathered" in.
Ground rods are best driven in w/ a LARGE hammerdrill w/ cup adapter, forget a sledgehammer.
Link Posted: 2/14/2006 7:21:49 PM EDT
Check that your power strip and power cord to your PC has all three pins on the plug.

I got shocked a few times when I used an amp that was not grounded. Didn't hurt, but you did feel it when you grounded yourself through your mic. Turns out it was a power strip that someone had cut the ground pin off of.

Link Posted: 2/14/2006 8:47:18 PM EDT

Originally Posted By Matthew_Q:
I got shocked a few times when I used an amp that was not grounded. Didn't hurt, but you did feel it when you grounded yourself through your mic. Turns out it was a power strip that someone had cut the ground pin off of.



Sorry but I don't buy that. Neutral and ground are the same potential. There was another problem if you got shocked that easily.
Link Posted: 2/14/2006 8:53:48 PM EDT

Originally Posted By Tim84K10:

Originally Posted By Mike_Mills:
Eight feet minimum, how do they drive that in?????



With a hammer.


I fuigure Chuck Norris just gives it a harsh look and it sinks into the ground in fear.
Seiously, poor grounding is a big problem in power circuts like this. Im not into the residential end of this stuff but I thought that when the power company did the hook up they did the ground burial as well.
Link Posted: 2/14/2006 9:01:25 PM EDT

Originally Posted By Tim84K10:

Originally Posted By Matthew_Q:
I got shocked a few times when I used an amp that was not grounded. Didn't hurt, but you did feel it when you grounded yourself through your mic. Turns out it was a power strip that someone had cut the ground pin off of.



Sorry but I don't buy that. Neutral and ground are the same potential. There was another problem if you got shocked that easily.


Not necessarily so. Ground and neutral are NOT the same. I see 120 VAC circuts in industry all the time that are not grounded properly, steped down in equipent cabinets from 480 to use as control voltage or any other use. Not to mention DC voltage in 24 VDC apps that will drag down (crowbar is an old term) if you ground neutral. But I digress. Its still possible to have a poor ground in a home and a good neutral from what the IBEW types tell me. Im strictly industrial.
Link Posted: 2/14/2006 9:13:43 PM EDT

Originally Posted By MEI2757935:

Originally Posted By Tim84K10:

Originally Posted By Mike_Mills:
Eight feet minimum, how do they drive that in?????



With a hammer.



It's very simple really. They just throw it into the ground really hard and it goes exactly 8 feet into the ground.

<­BR>





Ok, I'm an electrician, and figured I'd heard it all.......


But that made me fuckin laugh like a mofo ! Good one !
Link Posted: 2/14/2006 9:14:17 PM EDT

Originally Posted By zoom:
Check the voltage between the ground and neutral. I've seen this problem many (more than a dozen!) times. Usually the neutral isn't bonded to ground at the fuse box when this happens.z



The neutral isn't securly attached to the neutral bus (not sure about terminology) in the fuse box? Or neutral bus is not securly grounded?
Link Posted: 2/14/2006 10:08:21 PM EDT
Link Posted: 2/14/2006 10:24:43 PM EDT

Originally Posted By Troy:
NEC requires an 8' long, 5/8" diameter copper grounding rod, and that the fuze box/breaker panel is bonded to it with no less than 6ga solid copper wire.

In the vast majority of the areas I work in (suburban), no problem, but I've ran into a few houses with grounds that weren't to code. Quite a few are using rebar as the grounding rod, and some use water pipes.

My business partner got zapped bad on a panel that wasn't grounded at all. It seems that the morons shorted their main box (probably trying to steal power), and then cut the ground when they couldn't keep their breaker on. Those folks didn't get installed...

-Troy





Just for conversation's sake, bonding to rebar in a building foundation IS an acceptable means, per the NEC..... Of course, it has to stand up to certain other criteria (buried in a specific amount of concrete, etc) but it actually is legal and approved. Some places you just can't drive a ground rod. Now, if they're using it AS a ground rod, just hammering it into the ground, then that's a no no.

John


Link Posted: 2/14/2006 11:10:02 PM EDT
[Last Edit: 2/14/2006 11:14:00 PM EDT by Tim84K10]

Originally Posted By tnek:

Originally Posted By Tim84K10:

Originally Posted By Matthew_Q:
I got shocked a few times when I used an amp that was not grounded. Didn't hurt, but you did feel it when you grounded yourself through your mic. Turns out it was a power strip that someone had cut the ground pin off of.



Sorry but I don't buy that. Neutral and ground are the same potential. There was another problem if you got shocked that easily.


Not necessarily so. Ground and neutral are NOT the same. I see 120 VAC circuts in industry all the time that are not grounded properly, steped down in equipent cabinets from 480 to use as control voltage or any other use. Not to mention DC voltage in 24 VDC apps that will drag down (crowbar is an old term) if you ground neutral. But I digress. Its still possible to have a poor ground in a home and a good neutral from what the IBEW types tell me. Im strictly industrial.



It sounds like what you're describing is either old, ungrounded systems. I work on industrial equipment every day and I can't say that I've ever ran a 120 volt circuit where N did not = Ground but, I work in a fairly new building where EVERYTHING is grounded, and of course Chicago has some of the most restrictive code in existance. They are seperate on the branch circuit side of the service because code requires it. Back at the service, they're tied together at a specific point that another guy here refers to as that the "Neutral is bonded to the ground at ..."

I'm not sure what you're referring to if you're talking about DC circuits but I'm not going to go there as it has nothing to do with this topic.

120 in an industrial environment has to come off of a transformer if it was once 480. Remember that the number "120" refers to the voltage from that line to ground. 480 is typically 480 line to line and 277 to ground in my building. Transformers will step this down to 208/120 if it's not going to be used as-is (at 480/277). After the transformer, on the secondary side, it must be grounded somewhere! This is because a transformer does not actually allow an "Electrical" connection between the primary and secondary windings...the connection is purely magnetic. What you might have experienced is someone installing a transformer without grounding the secondary side, which is not right.

Ultimately, any white wire in the building should be the same potential as ground. If there is any difference at all, you have a problem somewhere, no question.

We can go back and forth all day about the potential places for where you could possibly lose that connection, but I'm pretty sure it's a widely accepted fact that for the purposes of a voltage measurement, N = G.
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