Bonding/Grounding copper water lines

[GoldDigger]

So there is no EGC to your well pump motor?

It's OK. He didn't ground the well casing. :angel:
More seriously, my 10 year old submersible pump installation (290' down) does not have an EGC. Not even a grounded conductor (120/240.) All pipe in the well and all of the delivery piping is plastic.

 

[roger]

All of them have some form of isolation/insulation between it and the copper lines in the wall.

And your water has no minerals or salts in it?



Roger

 

[Saturn_Europa]

http://mobile.nytimes.com/2008/05/04/world/middleeast/04electrocute.html?referer=

Poor grounding has killed people. I'd leave it grounded and bonded as required by the NEC. I don't claim to be an expert. But I tend to listen to documents that are clearly defined and based on years of empirically gathered data and compiled by engineers, electricians, and inspectors.

Definitely an interesting fault that you had though. As others have mentioned I'm surprised it didn't clear an ocpd. But it may not have been a large enough fault. How long was the neutral energized? You mentioned you measured voltage. Was the neutral energized until the utility company came out and killed power?

 

[al hildenbrand]

RCMoon, I find your report interesting.

Everyone else, it occurs to me that the overhead PoCo service drop grounded conductor, when shorting to one energized service drop conductor may well have burned in two, with the transformer side burning clear of the energized service drop conductor, while the dwelling side welded to the energized service drop conductor. This would, indeed, put full line to line voltage on roughly half of the normal 120 Volt branch circuits. (Assuming a relatively high Ohm ground rod / water service connection to earth.)

RCMoon offers some compelling facts, to me. This is his home. He was there when the event happened.

RCMoon would measure the service center neutral as energized and, yet, the transformer side of the faulted service drop grounded conductor would have disconnected from the LOAD. BOTH RCMoon and everyone else is correct. . . the transformer neutral opened. . . depends upon your perspective.

In My Opinion, this is an extremely rare occurrence.

Don't have any gas pipes.
I didn't lose a neutral. My neutral got energized. It damaged a lot of stuff in my house, luckily the utility co reimbursed me for the damage.

. . .the water pipe since its already under the slab in the ground. . .

. . .the service drop hot wire insulation deteriorated or was rubbed off by a tree branch causing it to contact the bare neutral/ground wire that it was wrapped around thus energizing all my neutral and ground conductors in my house as well as my water line that the service ground is tied to. . .
Note: my water heater is piped with CPVC.
I was in my house and all of a sudden I heard a lot of popping and smelt and saw smoke coming from some surge protectors,
I immediately went out side and tripped my main 200 amp breaker.
I checked voltage coming in and found I had 220v between line side neutral and one hot leg and 220v between both hot line legs.
I checked the service drop wire myself and found what happened
the power company confirmed it and cut out the section and replaced it.
The voltage on my neutral damaged a lot of appliances and TV's, etc.

in my case it was the main service conductors from the service drop, which were probably #1 AL.

I'm on my own well so not tied to neighbors or any municipality water system.

Based upon the facts above, I believe the service drop is a modern triplex ACSR.

The PoCo will have a ground of its own at the transformer pole, a ground that is bonded to the service drop grounded conductor. Isolating the conductive surfaces and systems of the house from bonding to the Main Bonding Jumper is a formula for disaster whenever the insulation integrity fails on the current carrying paths on the load side of the Service Disconnect.

 

[user 100]

RCMoon, I find your report interesting.

Everyone else, it occurs to me that the overhead PoCo service drop grounded conductor, when shorting to one energized service drop conductor may well have burned in two, with the transformer side burning clear of the energized service drop conductor, while the dwelling side welded to the energized service drop conductor. This would, indeed, put full line to line voltage on roughly half of the normal 120 Volt branch circuits. (Assuming a relatively high Ohm ground rod / water service connection to earth.)

RCMoon offers some compelling facts, to me. This is his home. He was there when the event happened.

RCMoon would measure the service center neutral as energized and, yet, the transformer side of the faulted service drop grounded conductor would have disconnected from the LOAD. BOTH RCMoon and everyone else is correct. . . the transformer neutral opened. . . depends upon your perspective.

In My Opinion, this is an extremely rare occurence..........

GoldDigger mentioned something similar to this towards the beginning of the thread. The poco fuse may very well have had a problem, giving that svc neutral enough time to burn open- sole fault path to transformer was then gone yet power continued to flow under the conditions you described.

Unfortunately, the op was shaken up enough and can't seem to be convinced that he shouldn't do away w/ bonding his pipes because of an isolated incident such as this, as the thread has morphed into trying to persuade him that what he is proposing now can be deadly .:happysad:

 

[Little Bill]

I watched the video. Funny as I had just watched it a couple of weeks ago. I thought things posted here sounded familiar.
As was said, the OP only heard part of the story. Mike was talking about bonding isolated parts, parts that had no potential to start with. He said it was crazy to deliberately energize something that had no potential to start with. He was sort of relating it to bonding roof flashing which brought a potential to it when it had none to start with.
Case in point, satellite installer was getting shocked when he touched the bonded roof flashing and his cable at the same time.

@RCMoon: If you want to settle this why don't you email or contact Mike Holt and ask him what he said/meant?

 

[al hildenbrand]

GoldDigger mentioned something similar to this towards the beginning of the thread. The poco fuse may very well have had a problem, giving that svc neutral enough time to burn open- sole fault path to transformer was then gone yet power continued to flow under the conditions you described.

Unfortunately, the op was shaken up enough and can't seem to be convinced that he shouldn't do away w/ bonding his pipes because of an isolated incident such as this, as the thread has morphed into trying to persuade him that what he is proposing now can be deadly .:happysad:

Yes, GoldDigger did:

Unless a compromised neutral blew first. One fault leading to the other.

To the OP: An energized neutral in combination with a high water pipe to soil resistance could create a dangerous shock hazard between bonded metal or water and a true earth ground like metal drain piping.
Adding another ground rod would be next to useless and not bonding neutral to water pipe would be an NEC violation.
Adding a bond to the drain piping too, although not required by code, would address this particular problem.

GoldDigger offers the seed of a solution, as well, but RCMoon could help with more details. . .

To RCMoon, You live in the State with some of the heaviest lightning activity. You describe your home as having a metal water supply from a well where the water pipe runs under the slab. This says, also, to me, that your concrete slab home floor is a strongly grounded surface.

RCMoon, you haven't directly said, but it sounds like your electrical service is the ONLY customer on the PoCo transformer. Is the PoCo transformer on a spur of PoCo primary transmission line ending at your transformer? Consider this, a cloud to transmission line strike will travel as a large voltage surge on the transmission line and, when arriving at the transformer a large portion of the surge will reflect off the impedance change at the transformer primary and the surge will double back on itself. In that instant, and for the duration of the surge at the transformer, the surge voltage will effectively double.

Even a cloud to cloud lightning discharge can produce an electromagnetic pulse that will induce a huge voltage surge on the transmission line supplying your PoCo transformer.

Your creating "air gaps" between the metal water piping, and other grounded conductive surfaces, and your branch circuit current carrying conductors turns those "air gaps" into lightning arresters INSIDE your house.

In addition to bonding to any metal piping to the Main Bonding Jumper, I'd suggest trimming your trees around the service drop. You get, what?, thousands of nearby lightning bolts a year, and you've had the neutral energized by a line conductor once in half a century?

 

[rcmoon]

Yes, GoldDigger did:



GoldDigger offers the seed of a solution, as well, but RCMoon could help with more details. . .

To RCMoon, You live in the State with some of the heaviest lightning activity. You describe your home as having a metal water supply from a well where the water pipe runs under the slab. This says, also, to me, that your concrete slab home floor is a strongly grounded surface.

RCMoon, you haven't directly said, but it sounds like your electrical service is the ONLY customer on the PoCo transformer. Is the PoCo transformer on a spur of PoCo primary transmission line ending at your transformer? Consider this, a cloud to transmission line strike will travel as a large voltage surge on the transmission line and, when arriving at the transformer a large portion of the surge will reflect off the impedance change at the transformer primary and the surge will double back on itself. In that instant, and for the duration of the surge at the transformer, the surge voltage will effectively double.

Even a cloud to cloud lightning discharge can produce an electromagnetic pulse that will induce a huge voltage surge on the transmission line supplying your PoCo transformer.

Your creating "air gaps" between the metal water piping, and other grounded conductive surfaces, and your branch circuit current carrying conductors turns those "air gaps" into lightning arresters INSIDE your house.

In addition to bonding to any metal piping to the Main Bonding Jumper, I'd suggest trimming your trees around the service drop. You get, what?, thousands of nearby lightning bolts a year, and you've had the neutral energized by a line conductor once in half a century?

My well is approximately 100' from my house, my water line is PVC from the well to my house, my house is plumbed with copper pipe, I'm at the dead end of the poco primary lines and on my own transformer from poco, my service drop is approximately 200' long. The poco service guy who repaired the short on my service wires told me he's seen this many times cause most service drops conductors are old.

It just seems to me that once I eliminated any chance of my copper water lines from becoming energized that, that's the safer thing to do. Since there are many ways ones copper water lines could get energized, like in my case from deteriorated insulation or open neutral, an error with an appliance, etc.

 

[jim dungar]

The poco fuse may very well have had a problem, giving that svc neutral enough time to burn open- sole fault path to transformer was then gone yet power continued to flow under the conditions you described.

From what I read in Post #1, the fault was entirely on the LV side of the transformer.
The OP says the neutral was energized by one of the service drop line conductors (the event had nothing to do with the utility primary side). The OP has been adamant that the neutral conductor was never broken (such as no longer connected to the transformer).

He has never stated his reference points, but I assume he measured a N-G voltage, which is why he says the neutral was energized. Without knowing the 6 voltages L1-L2, L1-N, L1-G, L2-N, L2-G and N-G and where in the system they were made, it is hard to do more than make guesses.

Also, we have not been told the status of the N-G bonding and whether it was made upstream or downsteam from the L-N fault.

 

[user 100]

My well is approximately 100' from my house, my water line is PVC from the well to my house, my house is plumbed with copper pipe, I'm at the dead end of the poco primary lines and on my own transformer from poco, my service drop is approximately 200' long. The poco service guy who repaired the short on my service wires told me he's seen this many times cause most service drops conductors are old.

It just seems to me that once I eliminated any chance of my copper water lines from becoming energized that, that's the safer thing to do. Since there are many ways ones copper water lines could get energized, like in my case from deteriorated insulation or open neutral, an error with an appliance, etc.

But does the pipe go into the slab? As Roger mentioned earlier, how pure is your water?
And listen to Hildenbrand about the lightning and think about this- when you have air gaps combined with thousands or millions volts, what do you get?

 

[al hildenbrand]

My well is approximately 100' from my house, my water line is PVC from the well to my house, my house is plumbed with copper pipe, I'm at the dead end of the poco primary lines and on my own transformer from poco, my service drop is approximately 200' long.

Thanks for the details. And, from your description of first bonding the exterior mounted service center and service disconnect to a ground rod, and then going on to the metal water piping, I infer you have a single ground rod, and that the ground under the slab is fairly dry (think high Ohms, in spite of the pipe being metal and with a large surface area in contact with earth).

The poco service guy who repaired the short on my service wires told me he's seen this many times cause most service drops conductors are old.

Rather than being "old", ACSR triplex is far more likely to fail because it isn't maintained. Allowing trees to grow up into the ACSR introduces squirrels and other chewing critters that can simply sit at it and gnaw. Wind will move the tree and the ACSR, not necessarily in unison, and further abrade the insulation at contact. ACSR simply is not designed for incidental sustained contact with vegetation.

It just seems to me that once I eliminated any chance of my copper water lines from becoming energized that, that's the safer thing to do. Since there are many ways ones copper water lines could get energized, like in my case from deteriorated insulation or open neutral, an error with an appliance, etc.

On the branch circuit side of your Service Disconnect and Main Bonding Jumper, an error in an appliance will trip the branch circuit overcurrent device IF the water line is BONDED to the Service Disconnect. This trip indicates the existence of the "error" and calls your attention, as the electrician, to find it and fix it.

When you isolate the water line from the Main Bonding Jumper, leaving it only in contact with earth, there is ONLY a fault ( "error" ) current path through high Ohm earth back to the PoCo transformer. In my opinion, this will create the very thing you are fearing. The water line will be energized.

Your service drop failure has shown that the earth fault current return path impedance is too high to trip the internal, or external, overcurrent protective devices at the transformer. Removing the water line from the service further increases the impedance of the Main Bonding Jumper connection to earth.

Rather, I'd consider adding a Ufer (concrete encased electrode) out into the yard directly off your exterior mounted service disconnect. . . AND, keeping the water line bonded.

 

[don_resqcapt19]

GoldDigger mentioned something similar to this towards the beginning of the thread. The poco fuse may very well have had a problem, giving that svc neutral enough time to burn open- sole fault path to transformer was then gone yet power continued to flow under the conditions you described.
...

I would not expect the utility primary fuse to clear a fault on the secondary of their transformer.

 

[user 100]

I would not expect the utility primary fuse to clear a fault on the secondary of their transformer.

Probably a ridiculous question but could it be that the utility skipped/had faulty secondary protection?

 

[don_resqcapt19]

Probably a ridiculous question but could it be that the utility skipped/had faulty secondary protection?

The utility does not use secondary protection on their transformers. The only protection on the secondary side are the service OCPDs.
The typical fault on the secondary side of the transformer and the line side of the service disconnect clears itself by burning through.

 

[user 100]

The utility does not use secondary protection on their transformers. The only protection on the secondary side are the service OCPDs.
The typical fault on the secondary side of the transformer and the line side of the service disconnect clears itself by burning through.

I know they almost never do- that was why the "ridiculous."

A drop will continue to cook and do eventually what you said above- those conductors are for all practical purposes unfused.
Just wondering if had sec protection been available if it would have made any difference, and if it was if it being faulty would have contributed.

Still believe that whatever happened (poco's fault, other dark horse) he needs to keep his bonding.

 

[al hildenbrand]

The utility does not use secondary protection on their transformers.

I suspect that generalization is not always true.

In my Metro of 3 million, the primary local PoCo has a long history of putting into service single phase 240 / 120 Volt pole mount residential area transformers that have an internal secondary side circuit breaker. There is a primary side fuse hanging in the cutout connection to the Primary line.

The side of the transformer can has a hot stick operable lever for changing the state of the breaker.

 

[ActionDave]

The utility does not use secondary protection on their transformers. The only protection on the secondary side are the service OCPDs.
The typical fault on the secondary side of the transformer and the line side of the service disconnect clears itself by burning through.

A line to ground short on the secondary will blow the primary fuse. At least here it will.

 

[user 100]

A line to ground short on the secondary will blow the primary fuse. At least here it will.

And in many areas that is true- I know the pocos play by their own rules and a lot of drops do burn open but surely in a lot of places it wouldn't be acceptable (duh) to have drops/ug's catching on fire every time there was a sec fault.

 

[iwire]

A line to ground short on the secondary will blow the primary fuse. At least here it will.

Are you sure about that?

That would be odd, the primary fuse is generally sized to protect the grid not the transformer.

In the link below the secondary short kept going for 30 to 45 minutes until the transformer internal shorted and opened the primary cutout.

http://www.electrical-contractor.ne...p/topics/119389/4_RMC_vs_Utility_Current.html

 

[al hildenbrand]

Great pictures, Bob. It's always amazing, for me, to see what a plasma will do.
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