Ground problem? Help!

14 years ago

Hi, new member here.

After touching a non painted area of my computer case the other day I received a nice JOLT. (Not static. Constant current as long as my hand remained in contact with case.) After disconnecting components to isolate the problem, came down to ONLY the power supply, everything else unhooked. Still getting shocked. I turned OFF the switch on the power supply itself and still getting shocked. (Power supply plugged in but not switched on) Decided to replace the power supply. After replacement I wasn't shocked by the case but decided to hook my new multimeter to an unpainted surface on the case and the negative lead to the floor (stabbing through the carpet to the concrete underneath). Reading is 50v-70v AC depending on which part of the floor I contact.

After planting my bare feet firmly into the carpet I tested with positive lead on bare case and negative lead against my skin. Same reading, about 60v AC. (This changes to about 20V if I lift my feet off the floor, but still seated in metal desk chair.) Decided to test my other computer which is plugged into a different outlet (same room) and got the same readings.

Decided to then test the outlets in the room. These are standard U.S. 110v 3-pronged outlets. The readings are as follows:

Hot to Neutral - 122.4v AC

Hot to Ground - 103.2v AC

Neutral to Ground - 13.2v AC

I noticed that if I plugged in a power strip (3-prong style,empty) and switched it on, the outlet readings changed to:

Hot to Neutral - 122.4v AC

Hot to Ground - 64.8v AC

Neutral to Ground - 51.4v AC

I noted that the 60v reading i get from the computer cases

to the floor seems to match the voltage readings I get from the outlet when a bare power strip is plugged into it and switched on.

Sorry for such a long post I just wanted to be thorough with my description.

I can do these simple tests but I am ignorant when it comes to home wiring. Do these readings indicate a ground problem in the house wiring? Are these readings normal? Time to call the electrician?

I live in a single story house on concrete slab, standard US 110v 3-prong outlets and a 220v in the garage. House was built in 1952, originally had a fuse box but updated with breaker box some years ago. Readings taken with a very nice $450 Snap-On multimeter calibration good.

Any advice is greatly appreciated.

Sort by:Oldest

Comments (6)

itsunclebill
14 years ago
Unless the house has been rewired you have a 3 prong receptacle on a 2 wire circuit. Try using one of the receptacle tester lights - it will likely show some abnormality such as a missing ground.

Digital meters will measure induced voltage and an expensive one will do it better than a cheap one. Actually, you are better off using a cheap analog meter to measure line voltages and checking for grounds.

If the ground was hooked up to the receptacle in question the voltages from hot to neutral and hot to ground I would expect to see within a volt or so of each other. Neutral to ground should be within a volt or so of each other.

You probably got shocked because the hot wire shorted to the power supply case and since there was no ground at the receptacle the breaker didn't trip.

If testing shows no ground present, turn off the breaker and remove the receptacle to see if a ground wire is present. If a ground isn't present it's time to consider options. Check back for advice. If one IS present then you have a different issue and need to find out why the ground isn't running back to the panel.
joed
14 years ago
Your reading seem to indicate an open neutral or possibly a bootleg ground or both. Someone connected the ground to the neutral to fake a good ground connection. VERY VERY dangerous if that is what they did.
Related Discussions
chainsaw spark/grounding problem
Q
Comments (3)
It doesn't sound like a spark problem so there is no sense to further torture yourself. Make sure the plug is dry. Also try a new plug. Try emptying the tank and refilling with fresh fuel. Try to start with the air filter OFF. Other than that, the diaphram in the carb could be bad or dirty inside.
...See More
Soggy ground - is this a valve problem?
Q
Comments (1)
It could be a valve leak problem, but $200 seems pretty high to repair them (although I guess with inflation, it might not be). If it is a valve problem, you can probably get the parts for less than $10 at your local hardware or garden supply store. So it's not the parts, it's the labor. And, if you're handy around the house, you ought to be able to do this yourself. First, you'll need to find out what's leaking. (It could be a hole in your line, a loose connection, a connection that hasn't be properly sealed with tape or gunk or something else entirely. So you're going to have to dig up the line in the area where it's wet. That shouldn't be a problem, because lines aren't usually buried too deep (usually a matter of inches). You should have a diagram noting where the lines are, but if it's only a two foot spot, that shouldn't be hard to find the line. Once you have determined where the leak is, Then you'll better know what you're up against. It the line itself is leaking, you can either repair it, or replace it (repairing is a lot easier). Also, the line could very well be hard vinyl or pvc (making it even easier to repair. Also, if the line itself is pvc, it could be old, and could have been broken by any number of things). But,at least if you see the problem for yourself, you are in a better bargaining position. Here is a link that might be useful: Desert Gardens
...See More
foliage problem with in ground stone fruit trees
Q
Comments (4)
I wish I could help you but I honestly don't know too much about growing these fruits. They are all planted in my area, peaches are more challenging because there flower buds come out early(actually cherries too) and they get killed by frosts. People here mostly plant grafted trees. My grandfather planted a peach pit and even though it produced fruit, the fruits were very small and sour. You could just go to a reputable garden center/nursery and ask, or call some of the more reputable fruit tree catalogs and get there opinion. Good luck, and once again, sorry I couldn't be of more help! Andrew
...See More
Problem with ground layered portion and possibly parent as well
Q
Comments (4)
"LOL, As you know nothing of my hand size or my tossing technique this is absurd. Clearly not the issue here. Nor is drainage." Since you didn't give us any detailed info about your hand size or soil texture, it wasn't absurd IMO. Rhodies (and that includes azaleas) rarely if ever need fertilizer IME. I give mine a good layer of organic mulch, and that's it. No fertilizer ever, and they bloom and grow well. I have several different plants in the Lights series, and the only one that hasn't done well is the one DH ran over with the brush hog. Depending on your 10-10-10 solubility, amount of rain, evenness of distribution, and depth of mulch there is potential for harm since all rhodies are quite shallow-rooted, more so than most other shrubs. Is there anything else that is different? Here it's been dry, and that can cause stress. Is this plant slightly higher or lower than any of the surrounding plants? Is it closer to other plants than the other azaleas? Do you have any others of this same cultivar? Do you have critters that might be effecting the roots such as chipmunks or voles which cause untold damage in my gardens, though they seem to avoid the rhodies. (I am looking at what seems to be a hole between the roots of the nearby tree.) Has anyone used weed-n-feed on a nearby lawn area or any other herbicides that might have drifted or washed into the root zone of the plant? Can you add a photo of the wider area in case there is something else that might be apparent?
...See More
hendricus
14 years ago
Our house is from the same era and has grounds added on by running a single wire from an outlet to a water line. The wire is just wrapped around the line, no clamps.

We also have an updated circuit panel, the new circuits are grounded but not the old ones except as noted above.
donkeyspam
Original Author
14 years ago
Thank you for the replies so far!

An update: I decided to test the outlet again with a table lamp plugged into it instead of a bare power strip. Lamp has a standard GE 60w incandescent bulb in it. With lamp plugged in and switched on the readings became the same as the bare outlet with nothing plugged in:

Hot to Neutral - 122.4v AC
Hot to Ground - 103.2v AC
Neutral to Ground - 13.2v AC

Seems to be something about the power strips that cause the 60v readings from Hot to Ground and Neutral to Ground. I tried 2 other power strips I had lying around and got the same readings. Outlet returns to normal with the lamp plugged in and power strips removed.

Does this mean anything to you? Lamp is a 2-prong plug, no ground pin.

Also could you describe to me how to do a ground test on the outlets? (Very new at this, thank you.) I'll post those readings as soon as possible afterward.
donkeyspam
Original Author
14 years ago
thx for the replies folks!

Another UPDATE here.

Used the 3-prong outlet tester I got at the hardware store and sure enough all outlets in the house (except 2) show open ground.

The 2 "Normal" outlets are one that my 110v electric oven and washer are plugged into and another outlet on the other side of the same wall where the water heater, furnace and water softener are.

Since the water pipes for the house come in right between those 2 outlets I assume someone decided to ground just those 2 outlets straight down to one of the water pipes. At LEAST they did that to make the bigger appliances safer!

So there doesn't seem to be a ground wire running throughout the house from the breaker box in the garage. Just those 2 outlets have been individually grounded to the pipes. Sound about right?

Anyway someone on another forum has stated that I should either install GFCI outlets wherever I intend to use 3-pronged equipment like the computers.

My question is this: As I said before I'm very new to this stuff. Would a GFCI outlet have helped in the incident with my computer? Meaning if my power supply shortet to it's shell, energizing my metal computer case (as it apparently did), would a GFCI outlet have tripped and broken the connection saving me from the shock?

Someone also suggested maybe grounding a few individual circuits in the areas I was concerned about. Computers, refrigerator etc. The back bedroom is far from the water pipes so would it be possible to attach ground wires to the proper places on a few of the wall receptacles then drill a hole through the wall to the backyard and attach them to a grounding rod or something?
Ron Natalie
14 years ago
Yes, a GFCI will save you from injury from energised stuff. The only time it doesn't work is if you are in the legitimate circuit path. Imagine biting into a two wire cord.

You can attach ground wires back to the house ground. This is not any old water pipe or even any old ground rod. You can connect them to the original house ground rods or anything directly bonded to them.

Ground problem? Help!

Comments (6)

itsunclebill

joed

Related Discussions

hendricus

donkeyspam
Original Author

donkeyspam
Original Author

Ron Natalie

COMPANY

BUSINESS SERVICES

GET HELP

CONNECT WITH US

Ground problem? Help!

Comments (6)

itsunclebill

joed

Related Discussions

hendricus

donkeyspamOriginal Author

donkeyspamOriginal Author

Ron Natalie

COMPANY

BUSINESS SERVICES

GET HELP

CONNECT WITH US

donkeyspam
Original Author

donkeyspam
Original Author