# Floating neutral?



## Takideezy (Mar 19, 2017)

Called to new modular home, ran a dedicated circuit to serve the sump pump. Plugged in sump pump, reached in wet well to adjust float and felt an electrical current with hand in water and other hand on new concrete. WTF? Opened breaker, same feeling, pulled branch circuit neutral and ground and it cleared. Reconnected neutral, no tingle, landed ground...tingle is back. Grab a meter, measure 4VAC with probe in water and probe against concrete (4.2VAC if I stick the probe in spit). Go to the panel, it is a 200A underground service, requisite #4 to ground rods, bonding screw in panel. I drive a tapcon into the fresh concrete floor, snap on a meter lead and measure the same 4.2VAC between the neutral bar and the concrete, same reading for panel case and anything else that is bonded. I open the main breaker, same readings, I pull the grounds and the bonding screw, letting the neutral float and I get 6.2VAC from the neutral to my tapcon in the floor. It's late, dark, cold and the house isn't due for occupancy for another week. I cautioned the owner not to move in, contacted the electrician who did the service and he is going to work out the issue.

I'm guessing the the utility's neutral isn't bonded at the pole and that the other two services from this transformer have the same issue. None of the neighbors were home so I couldn't check. I would appreciate some help understanding what I'm seeing, from where I stand this ain't kosher.


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## RePhase277 (Feb 5, 2008)

The voltage is coming in on the ground from outside. Could be a bad neutral at a the transformer.


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## Takideezy (Mar 19, 2017)

The voltage is coming in on the neutral. I isolated the neutral by pulling grounds, opened the main breaker and voltage between neutral and my reference tapcon was still present.


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## frenchelectrican (Mar 15, 2007)

Takideezy said:


> The voltage is coming in on the neutral. I isolated the neutral by pulling grounds, opened the main breaker and voltage between neutral and my reference tapcon was still present.


Either bad POCO connection at the transformer or one of the home have bad neutral connection. but I am leaning toward to POCO side.


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## MDShunk (Jan 7, 2007)

It's actually a pretty common occurrence, but it generally goes unnoticed until it gets real bad. About a decade ago I got a provisional patent (which I never perfected into a real patent) for a device to be installed at the service entrance or CD pole that would detect such current and sound an alarm; intended for dairy farms. Cows will actually give less milk (because they drink less) when they're affected by this tingle. They're pretty sensitive to this. The more common term is "stray current" and not "floating neutral" by the way, but neither is more correct than the other.


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## splatz (May 23, 2015)

Takideezy said:


> I drive a tapcon into the fresh concrete floor, snap on a meter lead and measure the same 4.2VAC between the neutral bar and the concrete, same reading for panel case and anything else that is bonded. I open the main breaker, same readings, I pull the grounds and the bonding screw, letting the neutral float and I get 6.2VAC from the neutral to my tapcon in the floor.


I am going to say that this is the main clue, the voltage between your neutral and that tapcon in the dirt is lower when your neutral is bonded to your GES. 

This suggests to me that the voltage is coming from a neighbor's issue. When bonded, your GES provides a low impedance path for the return to the utility transformer, and the voltage gradient in the dirt shrinks.


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## MDShunk (Jan 7, 2007)

Everything can be done properly at the utility, this new modular home, and the neighbor's house, and you could still have 4 volts. Kirchoff's Law. Stew on that for a little bit.


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## splatz (May 23, 2015)

MDShunk said:


> Everything can be done properly at the utility, this new modular home, and the neighbor's house, and you could still have 4 volts. Kirchoff's Law. Stew on that for a little bit.


I will bite  Give a hint. At what node / point are you applying Kirchoff's law? 

The neutral lug on the utility transformer?


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## MDShunk (Jan 7, 2007)

splatz said:


> I will bite  Give a hint. At what node / point are you applying Kirchoff's law?
> 
> The neutral lug on the utility transformer?


Every service in North America has at least two paths to carry unbalanced current. One of them is the neutral in the service drop or lateral.


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## splatz (May 23, 2015)

MDShunk said:


> Every service in North America has at least two paths to carry unbalanced current. One of them is the neutral in the service drop or lateral.


OK and the second one is from the main bonding jumper through the GES through the dirt. This one is generally much higher impedance.


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## MDShunk (Jan 7, 2007)

splatz said:


> OK and the second one is from the main bonding jumper through the GES through the dirt. This one is generally much higher impedance.


Uh-huh. Kirchoff's Law says that electricity does not flow in the path of least resistance (common mistake). It flows on ALL available paths. Most of the time there are more than two, actually. TV cable shield. Figure 8 support wire on the telco drop. Water line. etc, etc.


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## MTW (Aug 28, 2013)

Interesting story I heard recently from an excavator. He was digging for a new septic system and accidentally hit the copper water line. Come to find out the appliances in the house got fried (house was vacant at the time) because the neutral had snapped at an intermediate pole and the water line was in fact the "neutral" for this house. Once he broke it, it lost its remaining path back to the source. I think the copper water line scenario carrying current scenario is far more common than we think since it goes unnoticed for so long. It's also why the water meter technicians use a big set of jumper cables before they change out a meter.


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## splatz (May 23, 2015)

MTW said:


> Interesting story I heard recently from an excavator. He was digging for a new septic system and accidentally hit the copper water line. Come to find out the appliances in the house got fried (house was vacant at the time) because the neutral had snapped at an intermediate pole and the water line was in fact the "neutral" for this house. Once he broke it, it lost its remaining path back to the source. I think the copper water line scenario carrying current scenario is far more common than we think since it goes unnoticed for so long. It's also why the water meter technicians use a big set of jumper cables before they change out a meter.


I have thought about this, you hear about a lot of accidents with this, including electricians. 

If you do a lot of service work, especially residential, would it make sense as part of your pre-flight safety checklist to just check for current on the GEC?


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## splatz (May 23, 2015)

MDShunk said:


> Uh-huh. Kirchoff's Law says that electricity does not flow in the path of least resistance (common mistake). It flows on ALL available paths. Most of the time there are more than two, actually. TV cable shield. Figure 8 support wire on the telco drop. Water line. etc, etc.


OK I was thinking more of the sum of all currents thing, but now I see what you're driving at. Even with everything proper there may be some not-that-low impedance paths parallel to the neutral conductor.


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## MTW (Aug 28, 2013)

splatz said:


> I have thought about this, you hear about a lot of accidents with this, including electricians.
> 
> If you do a lot of service work, especially residential, would it make sense as part of your pre-flight safety checklist to just check for current on the GEC?


Absolutely. Anytime I mess with a GEC for whatever reason, I always check to see if it's loaded or not.


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## MDShunk (Jan 7, 2007)

splatz said:


> If you do a lot of service work, especially residential, would it make sense as part of your pre-flight safety checklist to just check for current on the GEC?


Slow your roll.... there should be some amount of measurable current on the GEC if everything is properly installed, especially so if the load is highly unbalanced at the time your measure it. At what level this current flow becomes a concern is another matter, however. It's the dreaded "open neutral" where you start to get into danger. A "beast of burden" is a more typical tool to use for that testing purpose.


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## MDShunk (Jan 7, 2007)

splatz said:


> OK I was thinking more of the sum of all currents thing, but now I see what you're driving at. Even with everything proper there may be some not-that-low impedance paths parallel to the neutral conductor.


Yes, the current flow is (more or less) inversely proportional to the impedance of each available path. Ground rods and the earth might suck as a conductor, but conductor they are. Just pretty high impedance. There's still something gonna flow. In the case of the OP's modular... it's not at all unusual to have the utility transformer on a pole mere feet from the house.


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## Takideezy (Mar 19, 2017)

The utility pole with transformer is 200 yards across the road. Triplex overhead to a pole in yard feeding an inderground to this service and two overheads to an adjoining property. Looks like neighbor has a sevice to his home and a separate service to a large tin building.

Regarding comments about checking the GEC before disconnecting...curious what methods you employ to verify its not carrying excessive current. Thanks all for the enlightening discussion.


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## MDShunk (Jan 7, 2007)

Takideezy said:


> The utility pole with transformer is 200 yards across the road. Triplex overhead to a pole in yard feeding an inderground to this service and two overheads to an adjoining property. Looks like neighbor has a sevice to his home and a separate service to a large tin building.
> 
> Regarding comments about checking the GEC before disconnecting...curious what methods you employ to verify its not carrying excessive current. Thanks all for the enlightening discussion.


Snap an amp clamp around it.


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## frenchelectrican (Mar 15, 2007)

Takideezy said:


> The utility pole with transformer is 200 yards across the road. Triplex overhead to a pole in yard feeding an inderground to this service and two overheads to an adjoining property. Looks like neighbor has a sevice to his home and a separate service to a large tin building.
> 
> Regarding comments about checking the GEC before disconnecting...curious what methods you employ to verify its not carrying excessive current. Thanks all for the enlightening discussion.


The clamp on ampmeter useally do the trick and be aware you will read some current all the time if super low reading you should be ok but once you get over couple amps that where the issue start. ( but be aware of voltage if you ever disconnect the GEC )

I just have one not too long ago and I read the clamp on and it was showing about 18ish amps ( on 240 volt circuits L-N ) and found out the overhead drop neutral conductor was pretty much shot inside of old style splitbolt connector.


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## splatz (May 23, 2015)

Takideezy said:


> The utility pole with transformer is 200 yards across the road. Triplex overhead to a pole in yard feeding an inderground to this service and two overheads to an adjoining property. Looks like neighbor has a sevice to his home and a separate service to a large tin building.
> 
> Regarding comments about checking the GEC before disconnecting...curious what methods you employ to verify its not carrying excessive current. Thanks all for the enlightening discussion.


Clamping around the GEC would show you whether it's carrying current. However now that I think about it. If the unbalanced load happens to be low at the time, you won't see much current even if there's significant voltage there. 

So even with the current test, if you do have to open up the GEC best to do so with gloves on and check for voltage once it's open. Lest YOU should become the unbalanced load hand to hand


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## emtnut (Mar 1, 2015)

In the OPs case, GEC disconnected, he is just measuring from POCO neutral to earth (concrete floor).

I'd say there is a poor grounding wire on a transformer nearby (Copper theft ??). That, and/or LOTS of ground current in that area.


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## Wiresmith (Feb 9, 2013)

Takideezy said:


> Called to new modular home, ran a dedicated circuit to serve the sump pump. Plugged in sump pump, reached in wet well to adjust float and felt an electrical current with hand in water and other hand on new concrete. WTF?


what is X1 to service neutral and X2 to service neutral at panel, if they are different you may have a ground fault on the lower one. possibly the underground service


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## lighterup (Jun 14, 2013)

MTW said:


> Interesting story I heard recently from an excavator. He was digging for a new septic system and accidentally hit the copper water line. Come to find out the appliances in the house got fried (house was vacant at the time) because the neutral had snapped at an intermediate pole and the water line was in fact the "neutral" for this house. Once he broke it, it lost its remaining path back to the source. I think the copper water line scenario carrying current scenario is far more common than we think since it goes unnoticed for so long. It's also why the water meter technicians use a big set of jumper cables before they change out a meter.


here ...we are required to land in a continuous 
fashion , a jumper that is secured ahead of the meter
and then around the meter and re-secured on the 
opposite side of the meter for this very reason.


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## Bird dog (Oct 27, 2015)

As an aside, I worked one place that they wanted *everything* bonded. So much so that there were ground loops all over the place. Then, they wanted us to get rid of the stray current! :wallbash:


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## Takideezy (Mar 19, 2017)

hd13 said:


> what is X1 to service neutral and X2 to service neutral at panel, if they are different you may have a ground fault on the lower one. possibly the underground service


X1 and X2 to service neutral were balanced.

POCO was contacted and made a site visit, home owner phoned me and the Trobleman called me on my cell. He said everything looked fine and his load test was normal. I explained problem and asked that he check the other two services. He phoned back and said that they checked out, he also told me that he discovered a failed lighting arrestor on the pole. He said that a link was hanging within inches of the neutral and that that the at 7KV it could be causing the issue I described. A crew was coming later to make the repair, I will return later and see if this resolved the issue. I don't know squat about line work so pardon me if I got this wrong.


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## Wiresmith (Feb 9, 2013)

Takideezy said:


> X1 and X2 to service neutral were balanced.
> 
> he also told me that he discovered a failed lightning arrestor on the pole. He said that a link was hanging within inches of the neutral and that that the at 7KV it could be causing the issue I described.


from my understanding of whats going on i wouldn't expect the utility company issues to be the cause unless they have other problems as well. when you measured x1 and x2 to neutral were they exactly the same? not even a volt off? it still sounds like a ground fault to me (close to the building too).


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## Takideezy (Mar 19, 2017)

hd13 said:


> from my understanding of whats going on i wouldn't expect the utility company issues to be the cause unless they have other problems as well. when you measured x1 and x2 to neutral were they exactly the same? not even a volt off? it still sounds like a ground fault to me (close to the building too).


It was textbook 240V between legs and as I recall 120V to neutral, I know it was balanced to the volt, don't honestly recall the reading.


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## Takideezy (Mar 19, 2017)

Follow-up on this matter...after a couple of calls to the POCO they sent an engineer who confirmed my findings. Further investigation revealed that the #4CU ground wires at several pole mounted transformer locations along this line had been cut and removed. The POCO restored the grounds and the neutral voltage dropped to 2VAC. The engineer agrees that there are more issues and was surprised that they hadn't had a complaint from the area dairy farmers. They are continuing to monitor and make repairs.

Thank you all for your suggestions and input, this was good learning experience.


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## Bird dog (Oct 27, 2015)

Takideezy said:


> Follow-up on this matter...after a couple of calls to the POCO they sent an engineer who confirmed my findings. Further investigation revealed that the #4CU ground wires at several pole mounted transformer locations along this line had been cut and removed. The POCO restored the grounds and the neutral voltage dropped to 2VAC. The engineer agrees that there are more issues and was surprised that they hadn't had a complaint from the area dairy farmers. They are continuing to monitor and make repairs.
> 
> Thank you all for your suggestions and input, this was good learning experience.


Hopefully, they replaced it with hard drawn copper. It takes bolt cutters to cut it.


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## emtnut (Mar 1, 2015)

emtnut said:


> In the OPs case, GEC disconnected, he is just measuring from POCO neutral to earth (concrete floor).
> 
> *I'd say there is a poor grounding wire on a transformer nearby (Copper theft ??)*. That, and/or LOTS of ground current in that area.





Takideezy said:


> Follow-up on this matter...after a couple of calls to the POCO they sent an engineer who confirmed my findings. Further investigation revealed that the *#4CU ground wires at several pole mounted transformer locations along this line had been cut and removed.* The POCO restored the grounds and the neutral voltage dropped to 2VAC. The engineer agrees that there are more issues and was surprised that they hadn't had a complaint from the area dairy farmers. They are continuing to monitor and make repairs.
> 
> Thank you all for your suggestions and input, this was good learning experience.


Good to hear, who would have guessed that ??? :biggrin:


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## RePhase277 (Feb 5, 2008)

emtnut said:


> Good to hear, who would have guessed that ??? :biggrin:


I think post number 2 was pretty accurate as well, know what we know now:shifty:


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## Wiresmith (Feb 9, 2013)

thanks for the follow up, i still wouldn't rule out a ground fault on the underground


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## Wiresmith (Feb 9, 2013)

are there any 3 phase services in that area? like a commercial building, industrial plant, substation or farm with 3 phase? if so and your still communicating with power company representative ask if they use ungrounded wye primaries if you would please


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## mikewillnot (Apr 2, 2013)

MDShunk said:


> A "beast of burden" is a more typical tool to use for that testing purpose.


what is this?


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## Wiresmith (Feb 9, 2013)

mikewillnot said:


> what is this?


the guy that asks for your flathead and proceeds to use it to beat the heck out of a lock nut


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## emtnut (Mar 1, 2015)

mikewillnot said:


> what is this?


One a deez ....


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## Bird dog (Oct 27, 2015)

emtnut said:


> One a deez ....


https://hjarnett.com/product/super-beast-pulse-pn-hja-469-psco/


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