OT: Electrical Problem Question ???

[SPMN]

I have a strange problem in my shower. For a long time I could feel a slight shock when I touched the shower head or faucet handles with soapy hands, especially when I had cuts etc. on my hands.
I just hooked up a digital volt meter betweem the shower head and the drain. It bounces back and forth from 3.5 to 4.8 volts. I thought I could isolate the problem by flipping off circut breakers to find where the voltage was coming from. Even with all the breakers and the main breaker off I still have voltage.
My questions: Any Ideas where this may be coming from? Is it dangerous? How do I stop this? Have you ever heard of a like problem?
Thanks in advance
Kent

 

[Anonymous-0]

Had this same problem ended up being the hot water heater.

 

[tele tech]

Seems to me that if the main breaker is off,the voltage is perhaps "stray voltage" from some other source i.e. a neighbors well or maybe the power company has a transformer going bad and backfeeding through the earth ground.
Another possibiliy could be your service entrance conductors before the main "leaking" to ground through worn insulation or a bare spot.
In any case I think a call to your electric provider or a sharp electrician is in order

 

[RobMD]

This could be.. however, he said he turned all the circuit breakers off and it still does it.

I think you better get a master electrician to check out the grounding in your house.

 

[John T]

Not sure where your problem is buttttttttt Ive seen some awful strange things happen when theres a loose or resistive Neutral connection somewhere. The current is seeking a return path eleswhere in that case n might involve metallic water pipes or mother earth or water etc. Id also take a look at the service entrance ground where there ought to be a big copper wire from the service entrance panelboard or the meter base out to a driven ground rod or two.

Ima thinkin a Neutral or a grounding problem butttttt its hard to say just where sittin here

John T long retired electrical engineer n pretty rustyyyyy on this stuff

 

[Russ from MN]

We had a similar problem when I was young and I cleaned the pipes and wrapped a ground wire from hot to cold to the iron drain pipe. End of problem!

 

[Charles (in GA)]

Unplug EVERYTHING in the house, and garage, etc. Don't miss anything, get all clocks, fans, lights, computers, printers, the dryer, the fridge, the stove if you can, microwave, etc. Then try it. Could be that you have a device with the neutral and ground wires crossed up.

If it still does it. I agree that it may be a loose or poor system ground and poor bonding.

Charles

 

[John T]

Good point Charles n thats the same reason Neutral n Ground remain isolated n seperate in a building where a sub panel is served by a main service enrance panel. In those, of course, the Neutral and Ground DO NOT get bonded again like back at the main. If his N is being tied to the equipment grounding conductor somewhere out there he has created paralell current paths n possible potential voltage differences n maybe an OUCHIEEEEEE. Loose Neutrals, Neutrals tied to grounds at wrong places, bad grounds, maybe an appliance problem like you mentioned or a hot water heater mentioned below can alllllllll create problems which ma not be that easy to find until a competent electrician arrives. I know the theory but Id hate to have to go in the house n find it in 5 mins lol

Fun chat

John T

 

[JerryNTx]

Could it be that the telephone company has used a water pipe for grounding their equipment like they used to do here in my neck of the woods?

 

[MarkB_MI]

Sure sounds like grounding/neutral problem. Yes, it is potentially VERY dangerous.

The reason that opening all the breaker had no effect is that the neutral and ground are NOT SWITCHED.

There are probably multiple problems here. If you're not familiar with AC power, I'd follow John's advice and get a professional out there. My guess is that you don't have any ground rods, or they're not hooked up properly. At one time, it was legal to use plumbing for ground, but that's no longer legal because plastic pipe doesn't conduct. If there's any non-conductive break in the metal plumbing, you won't get a proper ground. This could be caused by plastic pipe, dielectric unions or any other non-conductive part.

 

[Anonymous-0]

You are reading stray voltage on a digital high impedance meter and 3 to 5 volts is not unusual nor would that shock you. I would think if you had a neutral problem that you would have a lot more problems than just the shower giving you a shock.
I would look at the possibility of it being a static charge build up as I also have that with my bathroom faucets sometimes as a static charge from your body discharges to the grounded pipe. Another question would be: do you have metal plumbing instead of PVC and if so is the piping bonded to the electrical ground? Is the drain that you measured against made out of metal and grounded?

As been mentioned an electric water heater with a partial short in the element could cause the problem and the larger voltage may not show up on your test except when the thermostat has energized the element in the heater. Try your test again after you have run the hot water and the elements should be energized. Check your hot water line for a dielectric union that is an insulator to prevent electrolysis. You might have to put a bonding jumper around the union.

 

[John T]

Mark, you thinking he has a voltage difference between the water supply piping (perhaps via the water heater as mentioned below???) and the water drain piping or the water suppy piping and something else?????? I guess if its a cast shower or tub enclosure it may be electrically bonded to something OTHER THEN the drain piping???? buttttttttt most of that is allll plastic nowadays at least in the drain portion... I can envision the supply pipe at one voltage level (soundin possibly like water heater as a posted mentioned) but hows the tub or drain piping get at another??? The water heater shell is supposedly bonded to the equipment grounding conductor and I can see a bad or shorted element energizing a metallic pipe (OR TEH WATER) to the shower head, so how does the tub enclosure OR ITS DRAIN PIPE (IF METAL WHICH i DOUBT) get bonded to the water heaters outer sheet metal case?????????? Its easier to understand if it has metal drain pipe but if not looks like the shower needs a metallic base and it has to get bonded to the electrical system somewhere??????????

I charge you with the task of figuring this out n expect you to exercise diligence and all due dispatch lol

I dont think Id shower there in the meantime cuz it only takes like 50 milliamps through the old ticker to fib or defib or loose prime or whatever it takes to kill a body

John T

 

[dave guest]

Run into this maybe twice in 40 years. Power companys neutral has lost connection. May look OK but corroded or loose, oxidized. If all your grounding and bonding is perfect, you might never know. See if power company will disconnect and verify that their neutral is good. Since overhead line(I assume)can move in wind, condition may be intermittent. If you are in trailer park, lot more variables. Many of them do not use grounding rods. In a modern home you should have 2 or even 3 in some cases.

 

[Anonymous-0]

Electric water heaters can energize the water when an element gets a small hole in it.This is a common problem.When it happens in dairy barns the cows wont drink.It gets real dangerous around bath tubs.

 

[Anonymous-0]

I did appliance service for many years and found many water heaters that energized the water.The worst case was one where a small girl was shocked when the shower was turned on,This was an old house with cast iron drainage and copper plumbing.A heater element had a small hole in it ,It still heated the water.I could find no ground rod in the cellar.The service panel was grounded to the copper system ,but the water pump had plastic inlet pipe.I told the home owner to get an electrician in right away to install a proper ground rod.My old water heater had an element problem, the water heater fuse blew out.I found many mobile homes that had lost the ground connection.

 

[MarkB_MI]

Hey John,

I figure there's a lot of ways the shower drain could get grounded. It could have metal plumbing; my house (built in the '70s) has copper and iron sewer plumbing. Another possibility is that the shower sits on a concrete slab; that would make a good enough ground. Also, since your sewer lines are usually coated with wet slime, I think even a plastic line might conduct a bit.

36 coupe brings up a good point; the voltage may not be the result of a bad ground; it could be that the service is properly grounded but the plumbing is not bonded to ground as well. That could allow stray voltage to show up in the plumbing, even if there's no physical connection to power.

 

[Anonymous-0]

Over the years I've been called on to help with this problem a few times. Evey time I found the ground wire was broken underground near the ground rod. Latest code here calls for two ground rods. I now put in two and run separate bare copper wires to both. As others have posted there are other causes as well. Just all the ones I've found were the broken ground.

 

[SPMN]

Thanks for all the replies---My house is probably 35 years old--It's built on a slab and has copper plumbing---I'm pretty sure the shower drain pipe is all metal to the ground---I noticed this morning the meter was up to 5.5 volts---The temperature is 22--Would that make the voltage go up?---Thanks again
Kent

 

[John T]

I believe a problem like youre talking about may arise if the code requires ALL 8 FEET of the ground rod be totally underground and the installer didnt use ground wire clamps that were rated for direct burial........i.e. they corrode n you end up with a poor ground.......

Fun chat for sparky type guys huh

John T

 

[Anonymous-0]

I would bet that the drain pipe is black ABS plastic pipe for that time frame. Look at your vent pipes on the roof and see if they are plastic. That is why your voltage reading is so low as it is only stray or leakage voltage. That is also why the reading may vary with different factors such as time of day etc. I would really check the water heater elements and bonding of grounds, neutral, etc. I don’t like using a digital meter for that type of electrical problems because of mis-leading readings. I still use my Simpson 260 analog meter that takes a little current to read and not subject to stray voltage readings.

 

[Anonymous-0]

You can check your water heater by TURNING OFF AC POWER first and then disconnect the wires to the elements (usually two the upper and lower) Then this is where your digital meter should work fine. Use the highest ohms scale and check between each terminal and the metal grounded water tank housing and the reading should be infinity or open. Any reading indicates leakage - replace that element.

 

[paul]

Millions of dollars have changed hands on this 'stray voltage' issue on dairy farms. Cattle are _very_ sensitive to low voltage & will not drink water to avoid it.... This really hurts the paycheck of a dairy farmer. Many have gone out of business for it; many have sued the power co/ builder & recovered some income. Typically nothing is _wrong_ other than slight electrical potential is between different metal items that are not bonded to one another. It could be a loose nuetral or a loose ground tho, which is a bad thing.

Today any metal at all, from the rebar in the concrete, is all grounded together on a dairy building with many lbs of copper wire.

You have a grounding problem, which is likely minor, but possibly indicates something serious with the nuetrals.

So what to do? Ground all the metal parts of the bathroom & it will be safe. Have an electrician check out your grounding/nuetrals to see if there is a bigger problem. About all you can do.

--->Paul

 

[Anonymous-0]

I don't have an explanation as to why, but this happened to me in my second house, back in 1969. After much discussion, measurements etc by me, an electrician and the power company the problem was fixed by adding a new ground wire for the transformer.
It was a new service, pole, transformer and ground installed at the time the house was built. The ground ran down the side of the pole and was coiled on the bottom of the pole. Apparently the soil shrunk after backfilling the hole and was no longer contacting the wire.
The problem only happened several days after a rain. We found that saturating the ground around the pole with a garden hose fixed it. So a new wire ground was added. Apparently the difference in house plumbing and rod ground, compared to the transformer ground was the culprit.

 

[buickanddeere]

Lots of excellent answers and examples here what happens when there isn't a low resistance bond from everything metallic to true earth. Either from incorrect installation, age or abuse.
Frozen or dry earth has a poorer/higher resistance connection to ground rods. Thats why multiple deep driven ground rods and/or deep buried ground plates are required.
This is also why the ground wire should never be used by the lazy,cheap or ignorant person when a neutral is required.

 

[Ichabod]

Try googling for "stray voltage" and you will find plenty to read. Stray voltage is usually a bonding problem, not a grounding problem. I am an electric utility engineer and can tell you that not many in the industry know how to handle stray voltage. From what I have read the utilities in dairy country are much more knowledgeable because cattle are more sensitive to low voltage than humans. Some european codes require bonding all bathroom fixtures to eliminate stray voltage.
Google search: Stray Voltage

 

[Anonymous-0]

another thought on this, work in public water supply, at safety seminar years ago, was told if changing or disconecting a water meter to ALWAYS place a heavy jumper cable across meter or pipe opening from inlet pipe ( outside buried pipe to house side of opening) as feed back from electrical system has been known to kill if improper electrical grounds exist. at one time i believe elec code required a bond to plumbing. new water meters may be plastic not brass like old ones

 

[Anonymous-0]

Lots of the stray voltage comes from the voltage drop at the power pole ground rod. That's from the high voltage primary currrnt dividing between the neutral wire and the earth. Typically about half the primary current returns through the earth, but the resistivity of the earth near the pole leads to several volts drop. Its been standard practice (which I've tried to get changed, especially at dairy farms, but unsuccessfully) to tie the primary and secondary neutrals together at the transformer pole and connect them to a pole bottom or driven ground.

Then in the house the neutral is connected to the plumbing for an additional ground. But the drain plumbing that used to be metal is also grounded by being buried, but isn't bonded to the same panel neutral. That way there can be a voltage between the drain pipe and the water pipe. 2 volts between the milker and the water bowl is enough to make a cow object strenously because both ends are wet. A person in a shower is also wet and can feel a few volts. It probably isn't enough current to cause a shock problem but a shower is a bad place to be suprised enough to jerk and then slip and fall. So it needs to be fixed. I say, hook a wire between the drain pipe and the water pipe, close to the shower if handy.

Gerald J. electrical engineer in Iowa.

 

[Anonymous-0]

You might be getting feedback from a neighbor,this can be checked by taking an amp reading on both phases then subtract them this will give you your neutral current.Take a neutral current reading, if your neutral current is higher you are getting feedback.