romex jockey
Senior Member
- Location
- Vermont
- Occupation
- electrician
a rather excellent design comparison MBrooke ~RJ~
Voltage in Ground
- Thread starter Silverstang12287
- Start date
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mbrooke
Batteries Included
- Location
- United States
- Occupation
- Technician
It eliminates the hazards of an open neutral and stray current- but relies on an RCD to clear a fault.
romex jockey
Senior Member
- Location
- Vermont
- Occupation
- electrician
which incorporates nothing more than a toroidal ,like every other protective OCPD on the market
~RJ~
mbrooke
Batteries Included
- Location
- United States
- Occupation
- Technician
True indeed- but keep in mind that RCDs tend to be more complex than MCBs, so failure in theory is a higher probability with RCDs IMO.
I have a very similar problem to the OP. We got heavy rain 36 hours ago, and I went to rinse a paintbrush in my back yard. The ground was wet and I was barefoot. I felt a mild shock when I touched my spigot. I flipped off the main breaker in my homes service panel and broke out my multimeter. It was measuring 12 volts AC from earth to the spigot (I stuck the probe in the dirt for reference) with the power to my home turned off. I also measured the voltage between the ground of an outdoor electrical socket and the earth, and I got the same reading. 12 volts ground to earth.
I reached out to my neighbors to see if they had the same problem. I measured 13 volts from earth to my neighbors propane pipe that enters the house. I measured 10 volts earth to another neighbors spigot. Our homes are on large 1 acre lots. Power lines are above ground on our street. The propane home is at least 100 yards from me across the street, and their power line dips down from the pole and travels about 30 yards underground to the service panel. My other neighbor with the spigot measurement is down the street nearly a 1/4 mile, and their power is 100% above ground from the pole. We all have our own transformer.
I called out the power company to investigate. They said two years ago a new build on my street (about 1/2 mile down the road) had 8 volts on their ground, and the propane servicer wouldn’t fill their new underground propane tank. They “isolated the neutral” at that homes personal transformer. Still getting 8 volts on their ground and it was never resolved. Their issue was forwarded to Engineering and their conclusion is that the mountain we live on doesn’t ground well due to its rocky composition. Apparently they are still living with this condition.
So, the utility did the same thing for my personal transformer. They “isolated the neutral” on the transformer that feeds my home to mitigate any neutral to ground shorts that could potentially be caused by a neighbors home. No difference. I was still measuring voltage at my spigot when they disconnected power at the transformer. The utility people also got the same measurement at the spigot. It was actually reading nearly 18 volts at that point, so the voltage on my ground and spigot is actually fluctuating. They left and said my issue would be forwarded to their engineering department. I’m not hopeful.
I have an electrician scheduled to come to my home today and investigate. I’m reading zero volts neutral-ground in my homes electrical sockets, and 122.6 volts hot-ground and hot-neutral. I’m reading 8 volts ground to earth when sticking a probe in the earth using a spigot, an outdoor receptacle ground, and the electrical ground from my water heater as testing points.
A couple neighbors on my street reported that an electrician installed additional ground rods on their property after having received a shock from a spigot, and said this solved their issue. Does this make sense? I believe I have only one ground rod on my property. If extra ground rods will resolve this problem I’m all for it. I’m just worried an electrician will do that and it won’t solve the problem if it’s an issue with my power company.
I reached out to my neighbors to see if they had the same problem. I measured 13 volts from earth to my neighbors propane pipe that enters the house. I measured 10 volts earth to another neighbors spigot. Our homes are on large 1 acre lots. Power lines are above ground on our street. The propane home is at least 100 yards from me across the street, and their power line dips down from the pole and travels about 30 yards underground to the service panel. My other neighbor with the spigot measurement is down the street nearly a 1/4 mile, and their power is 100% above ground from the pole. We all have our own transformer.
I called out the power company to investigate. They said two years ago a new build on my street (about 1/2 mile down the road) had 8 volts on their ground, and the propane servicer wouldn’t fill their new underground propane tank. They “isolated the neutral” at that homes personal transformer. Still getting 8 volts on their ground and it was never resolved. Their issue was forwarded to Engineering and their conclusion is that the mountain we live on doesn’t ground well due to its rocky composition. Apparently they are still living with this condition.
So, the utility did the same thing for my personal transformer. They “isolated the neutral” on the transformer that feeds my home to mitigate any neutral to ground shorts that could potentially be caused by a neighbors home. No difference. I was still measuring voltage at my spigot when they disconnected power at the transformer. The utility people also got the same measurement at the spigot. It was actually reading nearly 18 volts at that point, so the voltage on my ground and spigot is actually fluctuating. They left and said my issue would be forwarded to their engineering department. I’m not hopeful.
I have an electrician scheduled to come to my home today and investigate. I’m reading zero volts neutral-ground in my homes electrical sockets, and 122.6 volts hot-ground and hot-neutral. I’m reading 8 volts ground to earth when sticking a probe in the earth using a spigot, an outdoor receptacle ground, and the electrical ground from my water heater as testing points.
A couple neighbors on my street reported that an electrician installed additional ground rods on their property after having received a shock from a spigot, and said this solved their issue. Does this make sense? I believe I have only one ground rod on my property. If extra ground rods will resolve this problem I’m all for it. I’m just worried an electrician will do that and it won’t solve the problem if it’s an issue with my power company.
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Quick update from another neighbor. Their son is an electrical engineer and did the following. This is him typing to his father so any references to the home are actually my neighbors home:
“a few years ago I checked the resistance (bond) of the ground at the pole to earth and the ground at your house to earth using an instrument designed for that measurement. The resistance was much higher at the pole than desired and I suggested you contact the utility to install a better ground at the pole. I don't think they've ever come to do that. I'll be back up there in a couple of weeks and I'll check the earth bond measurement again. (Ruthrj), I'm an electrical engineer and from what I've seen on this post about this and from my experience up on the mountain, you'll probably end up having to install some additional grounding to reduce any voltage between your grounded stuff (metal pipes, etc.) and the earth.”
I’ve owned several homes and never knew could be an issue, so this whole experience is eye opening for me. Maybe our utility provider isn’t grounding their transformers sufficiently, and property owners are having to compensate?
“a few years ago I checked the resistance (bond) of the ground at the pole to earth and the ground at your house to earth using an instrument designed for that measurement. The resistance was much higher at the pole than desired and I suggested you contact the utility to install a better ground at the pole. I don't think they've ever come to do that. I'll be back up there in a couple of weeks and I'll check the earth bond measurement again. (Ruthrj), I'm an electrical engineer and from what I've seen on this post about this and from my experience up on the mountain, you'll probably end up having to install some additional grounding to reduce any voltage between your grounded stuff (metal pipes, etc.) and the earth.”
I’ve owned several homes and never knew could be an issue, so this whole experience is eye opening for me. Maybe our utility provider isn’t grounding their transformers sufficiently, and property owners are having to compensate?
- Location
- Illinois
- Occupation
- retired electrician
Is the primary of your transformer connected line to line or line to neutral? If the connection is line to neutral, the voltage to earth is often caused by a primary neutral in poor condition and the current flowing on the earth via all of the grounding electrodes on the secondary side of the transformer(s). The quality of the "earth connection" is not really part of the issue, if that is the cause.
I just got off the phone with the engineer. He said we have single phase lines with the connection being line to neutral. I passed along your thoughts as they make a lot of sense. He responded that a bad neutral splice is “one of many possibilities”. Apparently this issue was reported by my property’s previous homeowner (as early as 2016!). The engineer said he’s been having trouble with this stray voltage for a long time, and that the complaints only seem to arise in summer. I’m guessing that’s when the earth has a higher moisture content from heavy rains in our area (or admittedly when people are more apt to touch their spigot and get mildly electrocuted). This would allow current to flow better through the earth, that’s for sure.
The engineer added ground rods to my neighbors home about a 1/2 mile down the street (2 at the service meter, 1 at the pole). This was done a couple years ago. He said the best improvement he saw for reducing the voltage at ground for that house was after he poured a bucket of water at the ground rods. I guess that’s the best he thought he could do before he said “the mountain doesn’t ground well” to them.
I reported my voltage measurements for my home as well as three of my neighbors. He is going to get assistance from the TVA which is over Huntsville Utilities as he can’t pinpoint the problem. I think I’m getting some traction from reporting how widespread the issue is up and down our nearly mile long street. There are at least 6 homes with these symptoms.
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- Location
- Illinois
- Occupation
- retired electrician
Adding ground rods just masks the problem...they need to fix the primary neutral. and the dryness in the summer along with more people out barefoot makes it worse in the summer time.
The connection to earth is not really an important part of the electrical system....except where you have an issue like an open neutral. If you have enough ground rods connected to the system, you may be able to get the voltage much lower, but that is not the correct solution. The correct solution is to identify and fix the problem.
Note that even where there are no primary neutral issues, you can see a couple of volts when you measure from a ground rod to "remote earth" as you are really measuring the voltage drop on the primary neutral. One definition of "remote earth" is a connection to the earth with a short ground rod or even a screwdriver that is at least 50' from any other grounding electrode.
Thank you sir! Regarding your couple of volts thought, I agree. Another neighbor down the street tested his spigot and he got a 2 volt reading. That sounded normal to me, much better than the 8-18 volts I’ve been experiencing.
I drove around the block and found that the guy with the 2 volt reading is on a different set of power lines than those experiencing problems on my street. The main line comes up the mountain and runs down the main road. His house is at the end of one set of lines connected to the main line, and my street is serviced by a second set of lines connected a little further down the main line. I forwarded that to the engineer to hopefully try and pinpoint the problem to our street.
- Location
- Illinois
- Occupation
- retired electrician
This should not be that difficult for the utility to identify where the problem is. Just start looking at the voltages from the grounding electrodes to remote earth along the path of the primary circuit starting at the substation where the primary circuit originates. The issue will be on the line side of the point where the voltage jumps up.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
And that fault could also be anywhere along the primary path upstream of your street. It may be between to populated areas or in another area that simply has not reported the problem yet.
(If everybody on your street shows the same voltage.)
You only need to sample one household for each distribution transformer secondary along the line.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
A primary neutral issue effectively makes everything downstream part of an SWER system.
I'd be interested in a voltage measurement between the transformer pole's GEC and the spigot.
I'd be interested in a voltage measurement between the transformer pole's GEC and the spigot.
Update, the engineer stopped by to verify all of the voltage measurements. They seem to be really stuck on this idea that a water heater element shorted, if not mine one of my neighbors. I reminded them the stray voltage seems to vary with respect to electrical demand. Low in mornings and it peaks in the late afternoon to evening. They didn’t say anything/blew me off.
They asked me again if I was sure my water heater was working ok. Again, the stray voltage is present with the main breaker off. They then told me my house didn’t appear to be grounded. I pointed out the ground rod which they hadn’t seen. They said well your water pipes must not be grounded. I said take a measurement on the ground of that outdoor receptacle. The potential should match the spigot (it did). I am extremely happy I was home when they showed up to hold their hand.
They scheduled somebody with the Tennessee Valley Authority to come out and investigate. They said they might send their own technician to come out again and disconnecting my neutral to see what happens. I reminded them that supposedly a tech already did that, and said they “isolated” mine. He said well I highly doubt that. When I asked why he said the tech probably just tightened some connections. They didn’t care to check any of the neighbors houses after I gave them another run down on their stray voltages.
After they were done, I asked for grins and giggles how well the ground rod was working at the transformer for my home. It measured 250 ohms! Yuck.
They asked me again if I was sure my water heater was working ok. Again, the stray voltage is present with the main breaker off. They then told me my house didn’t appear to be grounded. I pointed out the ground rod which they hadn’t seen. They said well your water pipes must not be grounded. I said take a measurement on the ground of that outdoor receptacle. The potential should match the spigot (it did). I am extremely happy I was home when they showed up to hold their hand.
They scheduled somebody with the Tennessee Valley Authority to come out and investigate. They said they might send their own technician to come out again and disconnecting my neutral to see what happens. I reminded them that supposedly a tech already did that, and said they “isolated” mine. He said well I highly doubt that. When I asked why he said the tech probably just tightened some connections. They didn’t care to check any of the neighbors houses after I gave them another run down on their stray voltages.
After they were done, I asked for grins and giggles how well the ground rod was working at the transformer for my home. It measured 250 ohms! Yuck.
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ptonsparky
Tom
- Occupation
- EC - retired
250 ohms. Are you on bedrock? or has enough current been passing to that rod that it dried out the surrounding soil? Did you happen to put clamp on that GEC?
I‘ve heard the story about ‘chemically’ treated rods behind construction food shacks that had unbelievably low resistance. Maybe those TVA techs will treat it for you.
I‘ve heard the story about ‘chemically’ treated rods behind construction food shacks that had unbelievably low resistance. Maybe those TVA techs will treat it for you.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
Well, unless you have a CEE, the NEC wants you to put in a second 250 ohm rod to get down to 25 ohms.
More seriously, the dry non-conductive soil, as long as it is not purr rock/gravel, will benefit from a chemical electrode kit.
But in any case it is not the right way to try to solve the problem. You should not be expected to complete the
POCO primary circuit!
Lots of rock below the soil. We are on a mountain in northern Alabama, about 1000 ft higher than the surrounding area. The soil is loam, not the dark red clay like down in the fields. The poles have been in the neighborhood since probably the 80s, but it’s mostly been empty lots. My home has been there since 97 I believe.
One of my neighbors sons discovered the high resistance at the transformer grounds a couple of years ago. Fingers crossed that renewed interest in the area and worry over this voltage will get a lot of issues sorted on the street!
- Location
- Illinois
- Occupation
- retired electrician
The use of more grounding electrodes or electrodes with lower resistance may mask the problem, but a connection to earth NEVER fixes an electrical problem.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
An excellent generalization!
Even for static discharge problems, an equipotential mesh, whether grounded or not, is the solution.
The power company has not pin pointed the cause yet. Last week they worked with the TVA, and they found the stray voltage at my property dropped 10 volts (16 down to 6) when they cut the power to my entire street.
The engineer mentioned prior to testing that they may have to run a new neutral line along the main road on top of the mountain. The trees up here fall on the lines often and he was worried about how many splices may be present on the lines. Not sure if his opinion changed on that after their observations. They’re still working with the TVA to continue investigating.
The engineer mentioned prior to testing that they may have to run a new neutral line along the main road on top of the mountain. The trees up here fall on the lines often and he was worried about how many splices may be present on the lines. Not sure if his opinion changed on that after their observations. They’re still working with the TVA to continue investigating.
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