# OT: voltage on my ground rod

I have a new house under construction, almost finished, but with no outside power source attached to it. My plumber noticed a tingle when
he touched a ground wire and the concrete in the garage. Sure enough, I measure 6/10 of a volt between the single ground wire from the house and the ground rod. I guess it's DC since the polarity changes if I reverse the meter leads. What's causing this?
Kingfish
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Kingfish Stevens wrote:

He wouldn't feel a thing with 0.6VDC -- any more than you feel while holding both ends of a 1.5VDC flashlight battery. Have you checked with your meter set to measure AC? The lower threshold that causes a 'tingle' varies with many conditions but will typically be at least 12VAC.
You will probably get more learned opinions here later but I wanted to get some reply to you right away.
--
Fred R
"It doesn't really take all kinds; there just *are* all kinds".
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Kingfish Stevens <> wrote:

Hmmm... I think you have more going on.
0.6V DC is almost impossible to feel, take for example a 1.5V flashlight battery. Have you ever felt current flow touching the terminals of one? How about a 12V car battery? DC is hard to feel at even higher voltages... (don't hold onto the car battery terminals while the starter is being engaged/disengaged, or you'll get hit with a higher Voltage 'spike')
I bet it's AC 'leaking' in from from some unknown source. It for sure needs to be found and positively corrected.
A local indoor public swimming pool had an issue like this. Someone discovered the water to be electrically 'hot'. I didn't follow the story all that close, but recall hearing the mystery current source didn't seem come from within the pool facility, and the pool was closed many month while they searched...
Erik
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The reason I thought it was DC instead of AC is because the +/- reading would change on my meter if I switched leads. I'll try sticking a test light on it this evening. And also see what the reading is with the meter in the AC position.
I couldn't understand how anything could be "leaking" since there is nothing hooked to the house. The temp service is sitting in the yard, no power to the house at all.
If this is something I putting back in the grid, maybe the power company will pay me for it ;-)
Kingfish

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<Kingfish Stevens> wrote in message

a low voltage (0.6V) could be caused by electrochemical reaction between soil moisture & earth stake perhaps. Like copper / iron nails in a potato or lemon etc.
Working in electronics you some times see 100+ volts of AC where you shouldn't - often its leakage from mains filter capacitors and due to its high impedance it dissappears if you use you fingers to short across the probes (not recommended if you are not sure what is going on). I wouldn't expect to see too much in a unconnected system - perhaps the wiring is picking up radiated power.
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On Fri, 18 Aug 2006 12:55:25 -0400, Kingfish Stevens <> wrote:

Well, for starters if you are feeling it, it isn't DC. Even at AC you need 2 to 4 volts to be noticeable unless your skin is salt-sweaty wet and very conductive. But it could be a big problem.
Check your temporary power pole feed to the construction site - if the Neutral connection coming in from the Edison transformer is open or not bonded properly and all the 120V loads are running on the ground rod connection for their return, it will energize the dirt in the vicinity of the ground rod. The voltage differential will lessen in "rings" going out from the rod, just like ripples in a pond when you toss in a rock...
Look at the voltages at the temp panel with a good Digital Voltmeter from each side to what you /think/ is ground, and then hit a large load on one leg - if the voltage to neutral (bonded to ground) sags on the loaded leg and spikes on the unloaded one, but the voltage from phase-to-phase stays at a rock solid 240V, it's an open neutral.
If this effect lessens if you trickle a garden hose on the ground rod and make a big ball of damp earth there to make a really good ground, you just confirmed it. Lowering the ground resistance with a big dose of water makes the alternative power return path work better, as the power makes it back to the transformer ground via the butt plate ground on the power pole, or the local ground rod at the underground transformer vault/pad.
Call the power utility and the company who leased you the temporary power pole, get them both out there pronto, and let them figure out who goofed and where. Either way, it needs to be fixed, and soon.
Until then, leave that garden hose trickling on the temp power pole's ground rod. And don't do any unnecessary work with older grounded-case power tools until it's sorted out. Lights and newer double-insulated tools okay if you are careful.
And no computers, televisions or sensitive electronics on that service until it's fixed - they tend to go blooey and turn into expensive paperweights when you hit them with big voltage spikes and sags.
--<< Bruce >>--
--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
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Thanks Bruce. I'll check this out tomorrow. I did test again this afternoon and you could not fill the tingle, but the volt meter was reading 0.9 volts (9/10). As far as I know, this one ground (rod) is the only one the house has. There is one, of course, at the temp pole. We will get the final next week and the power company will turn the power on. I'll ask them what's going on when they get there.
KS
On Fri, 18 Aug 2006 18:58:59 GMT, Bruce L. Bergman

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On Fri, 18 Aug 2006 12:55:25 -0400, Kingfish Stevens <> wrote:

The 0.6 V jumps out as the drop across a typical silicon diode, and pretty high to be coming from just a galvanic junction.
Your first investigation should be where else is your house grounded - telephone service entrance? Satellite antenna entrance? Metal plumbing with earth or concrete contact? A heating control box bolted to a grounded pipe and bonded to the electrical ground? Two earth grounds at different locations can be at different potentials, but 0.6 V seems like a lot for that...
Are there any battery powered items installed? Like maybe a fancy thermostat connected to the heating control box? A TV cable box connected to the cable and to the house wiring? AC powered smoke alarms with battery backup? A security system with a battery and a telephone connection? Anything connected to a telephone line and any other wiring or plumbing?
If the potential really is from galvanic action, you probably want to find it before you bond the electrical system to the ground rod and let whatever it is start corroding away!
Loren
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<Kingfish Stevens> wrote in message

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Tom sez
And, Tom, you would presume that to be FM, no doubt.
Bob (knows all about that magic) Swinney

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I would not get too excited. The two components that matter are voltage and current flow. I'm thinking that there is an issue with either your service ground or the utility pole ground.
The typical service is 240 volt with the center of transformer tapped and grounded. This makes a single conductor to ground 120v. Safety issue. I'd rather get bit by 120v than 240v since as you double the voltage you quadruple the power.
Years ago, I read about ELF communications and for chits and grins, I drove two rods about 6 feet apart and connected my record player to it. 20 feet away and 6 feet separation I hooked up the speakers. I could hear the music from the record I was playing. Not very loud but it was audiable. I my speakers saw .6 volt or better.
Wes S
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On Fri, 18 Aug 2006 18:39:53 -0400, snipped-for-privacy@lycos.com wrote:

There was an article in Popular Electronics in the '50's about a scheme like that. I tried it. My friend and I could communicate several hundred feet from his house to mine with rods about 6 feet apart in each location.
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Don Foreman wrote:

Way before that there wuz "Ground Telegraph" in use. I remember reading how they would span rivers with it by sticking two rods into the ground (spaced a fair distance apart?) on each side of the river, applying a dc telegraph signal across the pair on one side and a sensitive receiving relay on the other.
Third pix down on left column here shows one:
http://tinyurl.com/r7xa7
Also, stuff on "earth batteries" makes inteesting related reading...
http://en.wikipedia.org/wiki/Earth_battery
Jeff
--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
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This has nothing to do with ground(s) but is interesting phenomena that can be confirmed by any old "open wire" lineman. If you stand underneath a large multi-crossarm telephone lead you can hear a faint sound from hash generated by the inductive cross-talk of all the overhead circuits. Minute magnetic effects among all the wires is the cause. On a much larger scale, the conductors of large power systems where they come into close proximity must be rigidly anchored in place to keep them apart. This is also true with respect to the conductors in large motors and generators.
Bob Swinney

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Robert Swinney wrote:

Ever seen shipboard welding? Pretty impressive to watch the fat cables slap against the steel deck as the welder strikes an arc.
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On Fri, 18 Aug 2006 12:55:25 -0400, Kingfish Stevens <> wrote:

You measure between the ground wire and the ground rod??? And you get voltage???
They should be connected but obviously are not.
UNLESS... you have a HUGE current going to ground and the resistance of the wire between your two probes gives: Volts=Resistance * Current
In either case, it sounds like the electrician needs to come back.
sdb
--
Wanted: Omnibook 800 & accessories, cheap, working or not
sdbuse1 on mailhost bigfoot.com
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On Fri, 18 Aug 2006 12:55:25 -0400, Kingfish Stevens <> wrote:

Um, you are measuring with a multimeter and do not know if you are measuring AC or DC (it is a setting on the multimeter)?
If so, I would ask an electrician for help, as you do not know how to use a multimeter.
I think that the first thing is to ascertain just what is going on. What voltage is between what objects at what setting of the multimeter?
How can there be voltage between wire going to ground rod, and ground rod, if they are connected? Are they, in fact, connected?
i
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On Fri, 18 Aug 2006 20:53:08 GMT, Ignoramus23732

It has a setting for AC and one for DC. What I meant by my polarity statement was to say that the voltage I was reading was a DC voltage. I figured it to be DC because the sign would change if I switched leads.

I should have made this clearer. Here's the long version. The plumber was finishing his installation of a tankless, gas hot water heater. The (three conductor) electrical wire, that operates the igniter, was roughed in. Since all the pipes are plastic, he would have felt no voltage between the HW heater itself and the electrical wire. But for some reason, he touched the ground wire and the concrete floor (in the garage) and felt this tingle. Now this is not a "stand your hair up" thing. He even mentioned wetting his finger when touching the concrete to feel it better. He knew there was on power hooked to the house, so he was asking me what was causing it. This is when I decided to put a meter on it. Between the ground wire (eventually going to the igniter) and the concrete showed 6/10 volts. Between the ground wire and the other two wires, nothing. The next day, the electrician finished hooking everything up. He drove his ground rod beside the (future) meter base and connected the one copper wire (from the main panel) to it. If I disconnect this wire from the rod, I can read a voltage of 0.6 - 0.9 between the wire and the rod.
So that's my story. My house is a battery, I guess.
KS

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On Fri, 18 Aug 2006 18:10:19 -0400, Kingfish Stevens <> wrote:

volts.
Is that 6/10 number 0.6 volts, or voltage that varied between 6 and 10 volts (6-10 volts)?
Is the ground wire, per chance, carrying any significant current (which is should not, ground is a non current carrying conductor).

??? You mean nothing between ground and hot wire (black)???

i

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On Sat, 19 Aug 2006 03:04:46 GMT, Ignoramus12890

It was 0.6 when I first tested it. This afternoon it was 0.9.

Understand that there is nothing hooked to the house. To operate a saw or something, an extension cord is run to the temp service, 75 feet away.

I'll try this but don't think it will have any effect.

A while ago someone asked "why so many OT subjects". It's simple. It doesn't matter what the question is, someone on r.c.m. will have an answer. I've lurked this group for a long time and have learned a lot about lots of subjects. I appreciate everybody's input to this question and to the group in general.
Kingfish
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