Calling MRB: Weird Current on Ground

[Falcon67]

One question with me lingers because Im the curious sort, you mentioned the transformers are underground in a vault filled with water. Is your water table that high that the vaults fill on their own from seepage?

Not to try and answer for the OP, but if his city is at all like my city and the pipes are older, it may just be leaks. Until our little city started a multi-million dollar project to replace all the main water lines in town (with a 50% increase in taxes to pay for it) it was not unusual for the water department to report monthly losses in the millions of gallons. Yes, millions. Lots and lots. Who the hell knows where it all went. It would easily double if we had a line break. Before they got more control valves in, we'd lose about 750,000 out of the towers on a major line issue. Also here were I work (in a larger city), the phone company vaults on the back side of campus typically have to be pumped out before they can work in there. Leaks from water lines running under the street. Water table is not high here at all.

 

[MrMark]

I don't like any voltage across the plumbing.

A handful of years ago a fella in Florida literally got thrown out of the shower after Lennar Homes subs improperly installed and wired in the central ac unit. Somehow 240 volts were traveling across this unsuspecting homeowners plumbing, and when he was in the shower, went to adjust the shower head and WHAM. Fella will never be right again and the lawsuit put the heating and ac and electrical contractor who did the original work for Lennar out of business.

I second posting this issue on Mike Holts forum, lots of talent contribute on his site, but don't get too pissed if they suggest hiring someone on your own to find the root cause of your issue. Also on Mike Holt chances are there are people who are familiar with the way the utility does things in your part of the world.

One question with me lingers because Im the curious sort, you mentioned the transformers are underground in a vault filled with water. Is your water table that high that the vaults fill on their own from seepage?

Yes. Brackish foul water fills the vaults. Depending on tide, the water level can be as shallow as 3-4 feet. The transformers and all the connections are submerged.

The City came out today with their electrician and I had him put his fluke clamp on ammeter on my neighbors water line and watch as I turned on the microwave. I just heard a "wow"! I am putting current out that is going back through my neighbors plumbing. He comes from a different handhole too. Basically, all the houses on my block are putting current on the ground line to the cold water. What is interesting is that I have checked the neighborhood and found that it is only this block and a couple of houses on the next block where this is occurring.

My current thinking is that the poco has a neutral that is abnormally high in impedance relative to what it should be. The poco has tested the neutral but I question whether it was sufficiently loaded by their test to show a high impedance line. In other words, I think the next step is to check the impedance. The weird thing is that the house on this block that is isolated from the ground path (with a plastic bushing) is not showing signs of a high impedance neutral.

More testing is needed here.

 

[MrMark]

I need to totally isolate my house from the water pipe and test voltage drop under load.

I am going to have to disconnect the dishwasher line to do this. I think that is the only ground path left that connects to water. I can disconnect gas appliances, and recirc pump and washer/dryer. Those are the only paths I can think of where electricity could get on water pipe.


so far I have always had a steady 118 v line to n and line to ground on both phases.

 

[cowboyjosh]

Not to try and answer for the OP, but if his city is at all like my city and the pipes are older, it may just be leaks. Until our little city started a multi-million dollar project to replace all the main water lines in town (with a 50% increase in taxes to pay for it) it was not unusual for the water department to report monthly losses in the millions of gallons. Yes, millions. Lots and lots. Who the hell knows where it all went. It would easily double if we had a line break. Before they got more control valves in, we'd lose about 750,000 out of the towers on a major line issue. Also here were I work (in a larger city), the phone company vaults on the back side of campus typically have to be pumped out before they can work in there. Leaks from water lines running under the street. Water table is not high here at all.

Im surprised your little city didn't turn into wetland from the leakage. Wow, millions a month; in Colorado and Arizona where we don't have a drop to waste, municipalities go all ape **** when they lose as little as 2-3% a month, at which point they start checking all the lines. It then usually surfaces that they found folks who were watering their lawns for free, by teeing the main line before the meter for their irrigation.

As for the original topic, unless I am missing something, my gut tells me something is amiss with the utility, no way should you be putting current out to the neighborhood. Have you spoken to any of your neighbors about this? I wouldn't modify anything at this point, I wouldn't install a dielectric union, different water meter, anything; nothing that could compromise your safety, if your not getting shocked off appliances or plumbing at this time, don't do anything that could change that until your poco, city, and whoever hell the else you can get involved can get definitive answers and provide resolution.

 

[MrMark]

This City is involved and learning. The poco is involved and the poco engineer is being involved by the City. The City tells me the poco EE is top notch. I think we will get answers here. I made the suggestion that they thermally image their neutral connections. We will get to the bottom of this. I was accepting of this being normal until I determined that it is confined to my block and the next one. I believe some current flow is normal but we are seeing way too much.

 

[mrb]

This City is involved and learning. The poco is involved and the poco engineer is being involved by the City. The City tells me the poco EE is top notch. I think we will get answers here. I made the suggestion that they thermally image their neutral connections. We will get to the bottom of this. I was accepting of this being normal until I determined that it is confined to my block and the next one. I believe some current flow is normal but we are seeing way too much.

good news (i have yet to proclaim something as not quite right and be 100% disproven )

 

[JBurgess]

My municipality requires something like this for water meters so their workers won't get fried changing meters. They still jumper them also.

 

[Underdog]

Mike Holt, That rings a bell. In the 80's attended his school in Tamarac, FL to help me pass my master electrician's test. Being mainly a residential electrician the delta/delta and delta/y stuff confused me but I did pass the exam taught by mike himself. I learned a lot of stuff mainly in the BS sessions after class (real world wiring). I've since left the field except for my own diy stuff. Most of this discussion goes over my head but in simple terms seems to me that you have a partial open ground from the electric company.

 

[MrMark]

Mike Holt, That rings a bell. In the 80's attended his school in Tamarac, FL to help me pass my master electrician's test. Being mainly a residential electrician the delta/delta and delta/y stuff confused me but I did pass the exam taught by mike himself. I learned a lot of stuff mainly in the BS sessions after class (real world wiring). I've since left the field except for my own diy stuff. Most of this discussion goes over my head but in simple terms seems to me that you have a partial open ground from the electric company.

I think that is essentially right.

 

[MrMark]

My municipality requires something like this for water meters so their workers won't get fried changing meters. They still jumper them also.

Would you pm me the link where you got that.

I would like to send that to the City water department. They are presently searching for a dielectric tailpiece for me and the boss is concerned for worker safety. They've had people shocked. They should have that device.

 

[mrb]

thats a meter yoke from Mueller http://www.muellercompany.com/water/products/default.aspx?catid=10

 

[MrMark]

thats a meter yoke from Mueller http://www.muellercompany.com/water/products/default.aspx?catid=10

Ahh, that doesn't look like it would help here.

edit: I mean it would avoid the need for the jumper for meter replacement but not with the current blocking aspect. I'll send them the link anyway, we don't have those and the City is going to have to do alot of meter swap outs in the very near future with the new fire code coming.

 

[MrMark]

Answers should be coming tomorrow.

 

[JBurgess]

I'll send them the link anyway, we don't have those and the City is going to have to do alot of meter swap outs in the very near future with the new fire code coming.

I assume you are referring to the sprinkler requirement. It does raise the question:

If the city disconnects the water for late payment (also turning off the sprinklers) and there is a fire, does the city have a liability for turning off the fire sprinklers?

 

[smilezrcool]

I am new to this forumn. I was reading your post about voltage. You said you had 118volts phase to ground and 118volts phase to ground. The voltage seems a little low but when you measured it what were the amps on each phase. Maybe you were pulling a large amount of amps this is why the voltage is lower than normal. If you share a transformer with your neighbor then the combined load you both are pulling is reducing the voltage plus the length of the service could effect the voltage you receive at your service meter. Do you have dimming lights or certain lights that get bright. Sometimes if the power company has a bad neutral connection on the transformer you can get stray voltage/amperage on other grounding devices. To check for a bad ground/neutral I would test the voltage pahse to ground on each leg in the breaker box. Remember the readings then I would place a glass of water in the microwave for about two minutes turn on the microwave and then check the voltage again and if there is a difference of three or more volts between phase and ground/neutral then I would say the power company has a bad neutral connection. Ex. 118 volts phase to ground/neutral and 121 volts phase to ground/neutral, I would say bad power company connection.

 

[MrMark]

check this continuation link

http://www.garagejournal.com/forum/showthread.php?t=83889

I will do the microwave test. I have done the microwave test a lot recently, but with regard to watching the splitting current.

We did a jumper between a house that was splitting current - jumper between the N j-block in the hand hole for the house and a spare on the transformer N j-block and the return N current split stayed about the same as without the jumper. About 1/3 of the current was splitting off to the water line.

The formula for those interested is as follows

Where I is the unbalanced N current returned from the phase legs, I1 is the N current on the Poco N wire and I2 is the N current on the water line:

I1 = (R1*R2/(R1 + R2))/R1 *I


If R1 and R2 are remotely close you are going to see the splitting like we are here.

R1 being the resistance of the 2/0 alum N wire and
R2 being the resistance of the water pipe - 6 inch ductile iron.

Iron has a coefficient of resistivity about 4 times higher than aluminum but the water pipe has much greater cross sectional area. Perhaps more than enough to offset its higher resistivity.

I find it interesting that 3 volt inbalance will indicate something is amiss. They did use the Beast, which is a 22 amp draw (big resistive load) and they did not note abnormal voltage fluctuation. It looks like the water path is doing a very good job.

 

[MrMark]

Well, today put a wrap on this weirdness.

The City came out and put in a very cool isolation tailpiece on the meter. All metal but very cleverly designed with rubber washer and rubber isolation under the union nut to block current flow. A very impressive piece of hardware from engineering standpoint.

Anyway, this did solve my little problem where I was putting around 50 percent of my neutral current down the water pipe. Now there is none and it is going on the correct N path, at least until it hits the next handhole J BAR.

I did a load test with the microwave (a poor man's Beast). The steady state voltages were right at 119 for both legs prior to test. With the microwave on phase B the phase B voltage dropped to 118 while the Phase A held steady at 119. Test passed. System completely normal.