Mystery voltage on galvanized propane line.

[Jawrenn18]

Good evening everyone. I have a mystery. I have been in the electrical field in commercial and residential for 32 years and never seen this and cannot figure it out.
Installed a stand by generator for a customer in a remote location. About 1 hour from any sizable city. We started today off with running control wiring for AC load management. This required getting into the crawlspace. Eww.
While down there my helper came out and said he thought the gas line shocked him. Yeah right. It's Sat and your hung over. Get to work.
Later on while making the connection to the gas tank I felt a very mild tingle. I almost thought I was imagining it. After 32 years carple tunnel is taking its toll and I often get nerve jolts that feel like electrical shocks. Kept working amd didn't feel it again.
An hour or so later while tying the load management contactor in my helper again said he felt a tingle. So this time we started investing.
Found the 3/4" propane gas line that's buried about 12 feet from the home runs under directly into the crawl space. Outside when measuring from the pipe to the bond wire we ran from the service we get between 1.5 and 3.2 volts. It varied. Under the house about 0-10 feet in it gets up to 6 volts. As you continue back under the house it begins to drop and goes to the 2-4 volt range.
We went as far as pulling the meter and disconnecting the generator incase there was bleed over from the battery into the grounds. No matter what we still get that same voltage range on the pipe in the same places.
I thought maybe it was an electrified fence that's solar powered. Nope. Turned it off and still there.
To deepen the mystery. We ran 3/4" polyethylene from the tank to the generator. There is only metal contact at one point near the generator it's about 2" into the ground. I got the same voltage there. Once I tied the gas bond back in I did not again read voltage at the generator but still had it at the pipe under the house.
I thought maybe bad neutral causing imbalance or trying to use the bond system as a grounding point but the voltage line to line is 230 and each leg is 115.5-116 even.
IIs it possible there's some sort of reaction going on on the gas pipe in the ground causing voltage? I'm also thinking maybe it's something AC system related as the furnace is gas. Possibly bleed through from capacitor when the power was off and leaking into bond wire when power is on?
Were headed back Monday and are going to disconnect all gas lines from appliances and disconnect the gas where it enters the house to see if we can get it to go away. I'm probly going to try and run a new polyethylene run to where the galvanized leaves the ground and see if that clears it.
Any advice is appreciated. Thanks in advance.

 

[LarryFine]

My first thought is a bad neutral connection, yours or someone else's.

When you pull the meter, the neutral is still connected.

How far away is the utility transformer?

What is the water supply, well or municipal?

How far away is the nearest neighbor or other service?

Do you have a cable-TV service? They can bring voltage in.

 

[GoldDigger]

Found the 3/4" propane gas line that's buried about 12 feet from the home runs under directly into the crawl space. Outside when measuring from the pipe to the bond wire we ran from the service we get between 1.5 and 3.2 volts. It varied. Under the house about 0-10 feet in it gets up to 6 volts. As you continue back under the house it begins to drop and goes to the 2-4 volt range.
We went as far as pulling the meter and disconnecting the generator incase there was bleed over from the battery into the grounds. No matter what we still get that same voltage range on the pipe in the same places.

Since the absolute voltage on the pipe is not going to vary noticeably over its length (unless it is carrying hundreds of amps), that means that the local earth voltage is varying by 2-4 volts as you move inside the crawl space! That means the current from some source is flowing through the earth, whether injected by the utility through your building GES or falling off with distance away from POCOs own pole-base ground system.
What has almost certainly happened is that the POCO metallic neutral conductor has been broken or compromised and POCO primary current is flowing through their transformer ground.
At the pole, the transformer secondary neutral is at the same potential as the POCO ground wire, which is above remote earth potential because of the contact resistance of their ground system. This would be a classic case of Neutral to Earth Voltage (NEV), and in the long run only POCO can correct it. You could do things with bonding to reduce the symptoms, but the problem would still remain.
Since there is a voltage gradient in the earth, there is also a risk that any metallic water supply and drain piping inside the house could be energized too.

 

[Jawrenn18]

My first thought is a bad neutral connection, yours or someone else's.

When you pull the meter, the neutral is still connected.

How far away is the utility transformer?

What is the water supply, well or municipal?

How far away is the nearest neighbor or other service?

Do you have a cable-TV service? They can bring voltage in.

Thank you for the reply and information. She's on her own transformer which is overhead and on a pole 50-70 feet from the home. It goes under ground from pole to house so definitely a potential for problems there. She says she's never noticed any flickering lights and we ran the microwave while checking voltage at the meter. I say microwave specifically because anytime I deal with power company neutral issues the microwave always makes the voltage go crazy. Not sure why but I'd like to know if anyone does.
Well water for sure. Water piping in the home appears to be poly/pex.
Nearest other service is 500-1000 feet down the dirt road. They have their own pole mounted transformer as well.
No cable TV but there is a phone line for internet that's active.
So the reason I'm not getting voltage imbalance at the meter is the the earth is providing enough grounding to balance the voltage? Interesting. One of my plans is to drive a new ground rod(s) and see if that helps. Her old one is galvanized and is rusted pretty good.
Thank you again.

 

[Jawrenn18]

Since the absolute voltage on the pipe is not going to vary noticeably over its length (unless it is carrying hundreds of amps), that means that the local earth voltage is varying by 2-4 volts as you move inside the crawl space! That means the current from some source is flowing through the earth, whether injected by the utility through your building GES or falling off with distance away from POCOs own pole-base ground system.
What has almost certainly happened is that the POCO metallic neutral conductor has been broken or compromised and POCO primary current is flowing through their transformer ground.
At the pole, the transformer secondary neutral is at the same potential as the POCO ground wire, which is above remote earth potential because of the contact resistance of their ground system. This would be a classic case of Neutral to Earth Voltage (NEV), and in the long run only POCO can correct it. You could do things with bonding to reduce the symptoms, but the problem would still remain.
Since there is a voltage gradient in the earth, there is also a risk that any metallic water supply and drain piping inside the house could be energized too.

Thank you for the reply. Trying to get the power company out to fix anything when everything works is going to be one heck of a job. If I can convince them to shut off load side of the transformer and show them the voltage disappears on the gas line maybe I can get them to dig in further. Again thank you for the reply and information.

 

[retirede]

Thank you for the reply. Trying to get the power company out to fix anything when everything works is going to be one heck of a job. If I can convince them to shut off load side of the transformer and show them the voltage disappears on the gas line maybe I can get them to dig in further. Again thank you for the reply and information.

The power company should be more inclined to dig deeper if the voltage doesn’t disappear when they shut off the service. This would indicate that their primary is using the earth as a conductor, possibly as a result of a compromised primary neutral.

 

[kwired]

Thank you for the reply and information. She's on her own transformer which is overhead and on a pole 50-70 feet from the home. It goes under ground from pole to house so definitely a potential for problems there. She says she's never noticed any flickering lights and we ran the microwave while checking voltage at the meter. I say microwave specifically because anytime I deal with power company neutral issues the microwave always makes the voltage go crazy. Not sure why but I'd like to know if anyone does.
Well water for sure. Water piping in the home appears to be poly/pex.
Nearest other service is 500-1000 feet down the dirt road. They have their own pole mounted transformer as well.
No cable TV but there is a phone line for internet that's active.
So the reason I'm not getting voltage imbalance at the meter is the the earth is providing enough grounding to balance the voltage? Interesting. One of my plans is to drive a new ground rod(s) and see if that helps. Her old one is galvanized and is rusted pretty good.
Thank you again.

Because microwave is usually anywhere from 800 to 1200 watts and has higher current draw than many 120 volt loads in the house have. Most your higher wattage loads in the house are 208-240 volts and don't connect to the neutral so won't cause a bad neutral to do anything.

A heat gun is a great load to use for troubleshooting as it is also in similar load range.

 

[GoldDigger]

....

A heat gun is a great load to use for troubleshooting as it is also in similar load range.

In a pinch you can try a hair dryer, but those have much smaller heaters than they used to.
A free standing induction hob with a pot of water on it would be pretty good.
I used to have a 1000W incandescent light bulb in a Mogul socket that was fun to use.
A 1000W quartz-halogen work light is another alternative. (1000 or 2 x 500)

 

[tortuga]

She's on her own transformer which is overhead and on a pole 50-70 feet from the home. It goes under ground from pole to house so definitely a potential for problems there.

Is that service lateral before the meter? I bet that underground lateral has a fault.

 

[GoldDigger]

Is that service lateral before the meter? I bet that underground lateral has a fault.

Uninsulated aluminum neutrals inside a sheath corrode like crazy underground if the sheath gets nicked.

 

[kwired]

In a pinch you can try a hair dryer, but those have much smaller heaters than they used to.
A free standing induction hob with a pot of water on it would be pretty good.
I used to have a 1000W incandescent light bulb in a Mogul socket that was fun to use.
A 1000W quartz-halogen work light is another alternative. (1000 or 2 x 500)

Some hair dryers maybe smaller? I've seen some that say they are 2000 watts, can't recall for certain but seems like I've even seen something like 2250 watts before.

 

[tortuga]

The power company should be more inclined to dig deeper

What they do here for a single customer transformer is send troubleshooter and pull the cutout on the primary. If if it goes away they leave it off until the customer replaces their lateral.

 

[kwired]

What they do here for a single customer transformer is send troubleshooter and pull the cutout on the primary. If if it goes away they leave it off until the customer replaces their lateral.

If you have shut off your main and still have NEV a bad lateral isn't the cause and likely is still there after you replace the lateral. If they tried to make me do this I would likely be setting up a temporary grounded conductor laying on top the ground to show them there is still NEV even with a known good conductor.

 

[Jpflex]

Good evening everyone. I have a mystery. I have been in the electrical field in commercial and residential for 32 years and never seen this and cannot figure it out.
Installed a stand by generator for a customer in a remote location. About 1 hour from any sizable city. We started today off with running control wiring for AC load management. This required getting into the crawlspace. Eww.
While down there my helper came out and said he thought the gas line shocked him. Yeah right. It's Sat and your hung over. Get to work.
Later on while making the connection to the gas tank I felt a very mild tingle. I almost thought I was imagining it. After 32 years carple tunnel is taking its toll and I often get nerve jolts that feel like electrical shocks. Kept working amd didn't feel it again.
An hour or so later while tying the load management contactor in my helper again said he felt a tingle. So this time we started investing.
Found the 3/4" propane gas line that's buried about 12 feet from the home runs under directly into the crawl space. Outside when measuring from the pipe to the bond wire we ran from the service we get between 1.5 and 3.2 volts. It varied. Under the house about 0-10 feet in it gets up to 6 volts. As you continue back under the house it begins to drop and goes to the 2-4 volt range.
We went as far as pulling the meter and disconnecting the generator incase there was bleed over from the battery into the grounds. No matter what we still get that same voltage range on the pipe in the same places.
I thought maybe it was an electrified fence that's solar powered. Nope. Turned it off and still there.
To deepen the mystery. We ran 3/4" polyethylene from the tank to the generator. There is only metal contact at one point near the generator it's about 2" into the ground. I got the same voltage there. Once I tied the gas bond back in I did not again read voltage at the generator but still had it at the pipe under the house.
I thought maybe bad neutral causing imbalance or trying to use the bond system as a grounding point but the voltage line to line is 230 and each leg is 115.5-116 even.
IIs it possible there's some sort of reaction going on on the gas pipe in the ground causing voltage? I'm also thinking maybe it's something AC system related as the furnace is gas. Possibly bleed through from capacitor when the power was off and leaking into bond wire when power is on?
Were headed back Monday and are going to disconnect all gas lines from appliances and disconnect the gas where it enters the house to see if we can get it to go away. I'm probly going to try and run a new polyethylene run to where the galvanized leaves the ground and see if that clears it.
Any advice is appreciated. Thanks in advance.

If you wanted to know if the voltage was created by a chemical, temperature, etc reaction, use an oscilloscope and see if the voltage is Altering current AC at 60 hertz or a standard DVOM. Man made generated voltage will be at 60 hz AC

There are only a few things which produce AC naturally but typically wont yield a consistemt frequency such as 60 hertz. Some of these are in automotive circuits such as piezioelectric galvanic batteries (knock sensors) produce small AC, old cam gear sensors

Voltages created by reaction are often otherwise DC such as batteries through chemical reactions

Once you find its Ac look to utility neutral possibilities

 

[tortuga]

If you have shut off your main and still have NEV a bad lateral isn't the cause and likely is still there after you replace the lateral. If they tried to make me do this I would likely be setting up a temporary grounded conductor laying on top the ground to show them there is still NEV even with a known good conductor.

Here the service lateral is before the meter, so if you pull the meter the lateral is still energized.

 

[kwired]

Here the service lateral is before the meter, so if you pull the meter the lateral is still energized.

yes, but with no load on it when you turn off the main breaker there should be no NEV because of a bad neutral

Disconnecting the primary cutout doesn't disconnect the neutral which still will have any voltage rise on it that happens to be coming from the primary neutral.

 

[hillbilly1]

yes, but with no load on it when you turn off the main breaker there should be no NEV because of a bad neutral

Disconnecting the primary cutout doesn't disconnect the neutral which still will have any voltage rise on it that happens to be coming from the primary neutral.

It may not be a failing neutral, could be a failing hot.

 

[kwired]

It may not be a failing neutral, could be a failing hot.

How, without also compromising the neutral?

If it faults to the neutral, it probably not lasting very long and burns itself open causing more obvious problems or even opens overcurrent protection either in transformer (those that have it) or the primary cut out fuse. Neutral will need to have compromised insulation before than can happen though.

If aluminum conductor, which with residential distribution almost always tends to be aluminum, it will burn itself open in no time compared to copper

 

[hillbilly1]

How, without also compromising the neutral?

If it faults to the neutral, it probably not lasting very long and burns itself open causing more obvious problems or even opens overcurrent protection either in transformer (those that have it) or the primary cut out fuse. Neutral will need to have compromised insulation before than can happen though.

If aluminum conductor, which with residential distribution almost always tends to be aluminum, it will burn itself open in no time compared to copper

Happens very often with rock in the backfill. High resistance fault to moist soil. I wired a convience store many years ago. Another company wired the gas pumps. They used the rigid conduit as the egc, but failed to pull a bond into my panel, they used pvc between the panel and metal wireway outside. There was a #12 stripped back and laying live against the metal wireway. The complaint I got, was people were getting shocked from the metal doorknobs. 20 amp breaker with hundreds of feet of rigid in the ground, never tripped.

 

[Jawrenn18]

Thank you everyone for the ideas and replies. I'm only dubious of a bad neutral/on the buried lateral due to how well balanced the voltage is at the meter. I've seen plenty of bad laterals and with a load on them the voltage always get unbalanced. We will be back out this week and will do more poking around to see if we can figure it out. I'll post on what we find.