Well Pump Electric Shock
- Thread starter augie47
- Start date
- Status
hardworkingstiff
Senior Member
- Location
- Wilmington, NC
Sorry, I can't help, but if there is a story that prompted this question, I sure would like to read about it (here of course, not on the news).
ghostbuster
Senior Member
- Location
- Great White North
SG-1
Senior Member
- Location
- Ware Shoals, South Carolina
If the well casing is metalic I do not think you could get a better grounding electrode, it is about as grounded as it can get, maybe not bonded with an EGC. If it is PVC I do not think it is possible to ground it.
I do remember a thread where a ground fault on a well pump with a metalic casing with no EGC was the source of stray voltage hundreds of yards away on a different service.
I do remember a thread where a ground fault on a well pump with a metalic casing with no EGC was the source of stray voltage hundreds of yards away on a different service.
Thanks. I was in hopes of finding some I had read earlier about individuals being shocked while near the well other than folks working on it, but that one may have to do.
Every time the subject comes up on an inspection I try to explain the need for the EGC return path. I thought a little anecdotal evidence might help.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
In the recommendation to use "metal-sheathed cable", the description sounds like MI. A pretty expensive way to go, and not likely to make the sharp bends needed to enter the well without quite a loop.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Even if the well casing may make a better electrode it could not ever be depended upon the opening of a OCPD for safety and should never be used in the place of an EGC.
I must have missed that thread as it is impossible for a voltage to travel in earth from a distance of more then just a few feet, it might still be detectable at 26' but by the time you get to that distance it will be all but a few millivolts, stray voltage is a very local problem and is almost always caused by a voltage drop or loss of the service neutral or the MGN in the primary's brought to the location of the stray voltage via the EGC of the equipment in the local area of the problem, the only way that I could see that a shorted well casing would cause a voltage to appear over a hundred feet at a house on a different service would be that they are sharing the same well and have a metal pipe running from the well to this other location.
If you study this thread "Time to eat crow" you will understand why, the basics of it is simple, first you have to think in 3D in all directions as current takes all paths back to source and the small amount of soil around the injection point provides very few parallel paths and the resistance of these paths will be high, but the farther you get from the rod the more parallel paths through earth that lower the resistance which is also connected to all the reference points to the utilities neutrals which will give it a much lower resistance to the utilities MGN then it will to the injected voltage.
We had done some of the very same few voltage injection experiments back when I was doing studies at the University of Florida in Gainesville and is why I was trying to help Gary understand the results he was getting in that thread .
even at 3 feet from the injection point 75% of the voltage will be dropped, a better connection if anything would only cause the OCPD to open but the distance from the well casing would be the same and only depends upon the resistivity of the soil but in the opposite effect that you would think, the lower the resistance of soil will cause a smaller shell and the higher the resistance of the soil will cause a larger shell.
Another point when thinking about stray voltage is since current takes all paths back to source current won't take a straight line path between two points, in the above thread we saw this when Gary put voltage test points in the opposite direction from his service and got the same readings that he got from the ones toward his service.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
250.4(A)(5) clearly points out that an effective ground fault path needs to be used, and the fact that Earth shall never be used as this path as it can not ever be depended upon to allow enough current to flow to open the OCPD, also take a look at 250.112 and look at (L) and (M) not only is the pump required to be connected to the EGC but the casing also.
Point out that even if you could meet the 25 ohm minimum that the code allows that 120 volts divided by 25 ohms will only allow 4.8 amps of current to flow which would not even open a 5 amp fuse or breaker.
In the above link to the OSHA event we can see that even a well casing that was 120' deep did not provide a low enough impedance path to open the OCPD that fed this well and protect this worker. again the reason 250.4(A)(5) needs to be followed.
You should not have to educate an electrician when enforcing the code, although that article could enlighten them a little with some added words of what could happen if a person was hurt or killed because they didn't follow what the code says, that the fact they could be facing criminal judgments of man slaughter against them as many of us have seen and has been posted on here about.
And the fact they would have to live with the fact they cause a death to someone because they didn't want to follow the law, ask them what if it was a child in that article, would they be willing to live with that?
Invite them to the forum and we can explain why the Earth can not ever be use in place of a EGC.
This myth has been perpetuated over many years, and I find it many times coming from the utility side because they do use the Earth somewhat as a conductor, but it is not for fault current it is more to save on line loss and to allow smaller conductors to be used for the MGN, I have seen events that even at 7200 volts where the Earth would not open the primary line protective device, and a house (actually two) almost caught fire.
But I will point out that there are two errors in the OSHA article, one is that pump wire is an NEC and UL listed wiring method for wells (with an EGC of course) UF is not the only wiring method, and I have never heard of a copper sheath underground cable before? most of these pump wire cables are a 3 conductor red,black, and black with a green strip, for pumps with onboard starting caps, or red,black,yellow, and black with green stripe for ones with a control box that has the caps in it, for three phase pumps its BLK,RED,BLU,BLK/GRN ST., the installation sounds like the installer didn't have the correct cable for a 3-phase pump so they used the wires for a single phase pump with a control box without the EGC.
I believe these pump conductors have a UF listing as a single conductors and are listed under table 310.104 but I'm not sure about if this is correct or if they are listed as TW but I do know they are allowed.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
It is a little hard to tell from the description, without any graphics, but I get the impression that rather than being run through a fitting in the well casing or in the well cap, the pump wires were routed up the outside of the casing, bent over to go down the inside and then the well cap was jammed over the whole thing.
ptonsparky
Tom
- Occupation
- EC - retired
The metalic well casing is a Grounding Electrode. Don't confuse or mix it with the requirments for an EGC. We know they are not the same.
From my experience the problem was a remote well casing that had an ungrounded submersible pump. Electricians may have recognized the fact that these needed an EGC but well/pump installers did not. Believe it or not there are probably millions of these installs that were never seen by an electrician. Failure of the pump motor or leads to it would energize the casing either with direct contact or through the water. The current direction was from the casing to the transformer, not the other way around.
From my experience the problem was a remote well casing that had an ungrounded submersible pump. Electricians may have recognized the fact that these needed an EGC but well/pump installers did not. Believe it or not there are probably millions of these installs that were never seen by an electrician. Failure of the pump motor or leads to it would energize the casing either with direct contact or through the water. The current direction was from the casing to the transformer, not the other way around.
The root cause of death of the victim is not bonding of the well casing. The initial shock (felt by the supervisor also) might probably be due to ground leakage current through the standing water around the well casing and subsequent falling of the victim on the energized well casing might have proved fatal. Had the well casing been bonded, OCPD might have operated and would have de-energized the well casing long before the victim could fall on it, thereby, could, perhaps, have saved his life.
Ah, even not bonding of the well casing may not be the cause of the death, because residual insulation value of the damaged insulation of the cable of the submersible pump might be high enough not to allow the OCPD to have operated, even when the well casing is bonded with EGC. So the real root cause might be not providing residual leakage current operated circuit breaker in the pump circuit. IEC long recognized it and mandate residual leakage current operated circuit breakers for circuits.
donaldelectrician
Senior Member
Nine-year-old Butler County boy electrocuted
June 13, 2011 | By Rebecca Gannon and John Boyd | KWCH 12 Eyewitness News
(BUTLER COUNTY, Kan.) ? A Kansas sheriff calls it a bizarre and tragic accident. It
happened about 7 miles south of Augusta in Butler County Friday evening; a nine year old
filling up a wading pool is electrocuted by nearby machinery.
Experts say the story of Zacharias Nelson is more common than you think.
It happened just steps away from Zachariah Nelson's Butler County home.
The nine year old filled up his wading pool Friday evening. He walked back across the yard, in his soaking black sneakers, to
turn off the water. His ankle came in contact with a metal well head cover -- and he was electrocuted.
He died steps away from his home.
"I think it's tragic that I think he touched this energized water well with his feet being wet," said Butler County Sheriff Kelly
Herzet, "it sent a volt of electricity through his body."
The metal well-head cover had four wires (red, white, green, and black) in it -- but only three were connected.
"Unfortunately, I won't say this is common," said Dan Ingalls, an electrician and manager of Butler County Buildings and
Grounds, "but it does happen."
The green one keeps it grounded, and safe. In Nelson's case, the green one wasn't connected.
So when the blonde boy with a missing tooth and winner of his school's citizenship award made contact with that electrified
metal cover, he had 220 volts surging through his body.
"It's a tragic accident, what occurred here," said Sheriff Herzet. "And I think the family wants people to know that people can
learn from this."
Ingalls agreed; "if we even get one person to call their electrician to come out and look at this, and if they have this same
situation, and if it gets corrected now - that's what we're after." Ingalls recommends calling an electrician to do it; do not do it
yourself. It may cost $100, but Ingalls said it is worth it -- especially when you consider what else it could cost.
Ads by Google Advertisement
Don
June 13, 2011 | By Rebecca Gannon and John Boyd | KWCH 12 Eyewitness News
(BUTLER COUNTY, Kan.) ? A Kansas sheriff calls it a bizarre and tragic accident. It
happened about 7 miles south of Augusta in Butler County Friday evening; a nine year old
filling up a wading pool is electrocuted by nearby machinery.
Experts say the story of Zacharias Nelson is more common than you think.
It happened just steps away from Zachariah Nelson's Butler County home.
The nine year old filled up his wading pool Friday evening. He walked back across the yard, in his soaking black sneakers, to
turn off the water. His ankle came in contact with a metal well head cover -- and he was electrocuted.
He died steps away from his home.
"I think it's tragic that I think he touched this energized water well with his feet being wet," said Butler County Sheriff Kelly
Herzet, "it sent a volt of electricity through his body."
The metal well-head cover had four wires (red, white, green, and black) in it -- but only three were connected.
"Unfortunately, I won't say this is common," said Dan Ingalls, an electrician and manager of Butler County Buildings and
Grounds, "but it does happen."
The green one keeps it grounded, and safe. In Nelson's case, the green one wasn't connected.
So when the blonde boy with a missing tooth and winner of his school's citizenship award made contact with that electrified
metal cover, he had 220 volts surging through his body.
"It's a tragic accident, what occurred here," said Sheriff Herzet. "And I think the family wants people to know that people can
learn from this."
Ingalls agreed; "if we even get one person to call their electrician to come out and look at this, and if they have this same
situation, and if it gets corrected now - that's what we're after." Ingalls recommends calling an electrician to do it; do not do it
yourself. It may cost $100, but Ingalls said it is worth it -- especially when you consider what else it could cost.
Ads by Google Advertisement
Don
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
The editor "corrected" jolt to volt?
weressl
Esteemed Member
If there is any justification ever slips into the NEC for other than receptacles and heat tracing, these would be the first candidates for GFP in my creation of the NEC. Certainly something along the line of heat tracing GFP, a higher level of leakage current allowance than just for plain receptacles/appliances.
The household EDP appliances (such as computer, printer etc.,) also, connected as receptacle load, may cause tripping of residual current circuit breaker in their circuit.
- Status