Objectionable Current - Water main

[don_resqcapt19]

Thought the same thing but if a toaster,coffee pot etc ( even with short cords ) on a GFCI protected circuit thought the GFCI would have a faster response time if sink was bonded. If a toaster that was plugged in but not on being they only have a two wire male plug ( no ground wire ) the GFCI might not trip and sink could be energised.

How would either of those two appliances energize the sink?

 

[jim dungar]

IMO, a kitchen sink is not “likely to be energized.”

I agree.

My example for possibly versus likely:
Yes, you could possibly win the lottery, however you are not likely to.

 

[mtnelect]

I agree.

My example for possibly versus likely:
Yes, you could possibly win the lottery, however you are not likely to.

Somehow ... GFCI/AFCI seems to fit the saying "Everything and the kitchen sink".

 

[kwired]

I agree.

My example for possibly versus likely:
Yes, you could possibly win the lottery, however you are not likely to.

I know somebody I wish you could convince this to.

 

[garbo]

How would either of those two appliances energize the sink?

Because water though not a great conductor will conduct electricity.

 

[don_resqcapt19]

Because water though not a great conductor will conduct electricity.

So you have a conductive path of water between the sink and the appliance with a two wire cord that also has a ground fault?

I still don't see that energizing the sink, and is well outside "likely to be energized" in my opinion.

 

[LarryFine]

How would either of those two appliances energize the sink?

Methinks he meant that a GFCI would trip more reliably with the sink being well-grounded.

 

[don_resqcapt19]

Methinks he meant that a GFCI would trip more reliably with the sink being well-grounded.

I really have no idea of what he intended to say.

Thought the same thing but if a toaster,coffee pot etc ( even with short cords ) on a GFCI protected circuit thought the GFCI would have a faster response time if sink was bonded. If a toaster that was plugged in but not on being they only have a two wire male plug ( no ground wire ) the GFCI might not trip and sink could be energised.

I see no way that the sink becomes energized.

If the metal sink has no connection to earth, there is no shock hazard and there would be no need for the GFCI to trip.

A bonded sink, in this application, only results in a short duration shock (the trip time of the GFCI) that would not even happen if the sink is isolated.

 

[LarryFine]

I see no way that the sink becomes energized.

A disposer or instant water heater, both of which (should) have EGCs.

 

[don_resqcapt19]

A disposer or instant water heater, both of which (should) have EGCs.

That was not the application that he posted.

 

[Rjryan]

Author's Comment:
Controversy about using metal underground water piping as a grounding electrode has existed since the early 1900s. The water industry believes that neutral current flowing on water piping corrodes hte metal. For more information, contact the American Water Works Association about their report—Effects of Electrical Grounding on Pipe Integrity and Shock Hazard, Catalog No. 90702, 1.800.926.7337. Figure 250-105 Mike's Comment from Grounding and Bonding

 

[Rjryan]

Author's Comment:
Controversy about using metal underground water piping as a grounding electrode has existed since the early 1900s. The water industry believes that neutral current flowing on water piping corrodes hte metal. For more information, contact the American Water Works Association about their report—Effects of Electrical Grounding on Pipe Integrity and Shock Hazard, Catalog No. 90702, 1.800.926.7337. Figure 250-105 Mike's Comment from Grounding and Bonding

American Water Works Association

American Water Works Association

Journal.

American Water Works Association

Peer Reviwed

Electrical grounding, pipe integrity, and shock hazard


Steven .J Duranceau, Melvin .J Schiff, Graham EC.. Bell

First published: 01 July 1998

https://doi.org/10.1002/j.1551-8833.1998.tb08467.x

Abstract

Electrical currents on metallic water service lines and mains affect corrosion of buried metal piping and can result in random shock hazards for water utility employees.


The practice of using metallic water piping as part of the electrical grounding system of a building has been commonplace for more than 80 years. Modern electronics such as variable-speed motors, televisions, and computers produce both direct current and alternating current (AC), which can flow along metallic water service piping. When electrical transformers serve multiple buildings, the water services and distribution piping can act as parallel neutral return paths for AC from building electrical systems to the transformers. AC can increase the rate of corrosion of distribution and service piping and create shock hazards for distribution workers. As long as the current remains on the electrically continuous pipe, corrosion is not affected. Corrosion occurs when current leaves the pipe and flows through the earth.



American Water Works Association

Journal.

American Water Works Association

Peer Reviewed


Effect of Grounding and electrical properties ON WATER QUALITY

Graham EC.. Bel, Steven .J Duranceau

First published: 01 May 2002 https://doi.org/10.1002/j.1551-8833.2002.tb09475.x *

To whom correspondence should be addressed


Abstract

The use of metallic water piping as part of a building's electrical grounding system has been a commonplace practice for more than 80 years. When electrical transformers serve multiple buildings, the water services and distribution piping can act as parallel neutral return paths for stray current from building electrical systems to the transformers. Electrical resistance in pipe connections, fi present, forces some fraction of the stray current to flow through the parallel water path. Discharge of current on the inside of the pipe increases metal release. Previous studies on the effects of grounding on water quality and metal release did not investigate the effects of resistance or dielectric fitting. This study investigated the effects of dielectric fittings on water quality.


Copper tubing that had been modified with inserted dielectric fittings was filled with potable water from two different water sources and was tested with applied alternating current (AC) voltages of up to 123 Vfor periods of up to 110 h. Significant increases in copper, lead, and zinc in stagnant potable water were measured in less than 24 h at


applied voltages of ~50 VAC. Metal release generally increased with charge transfer, in accordance with Faraday's law.

 

[garbo]

Author's Comment:
Controversy about using metal underground water piping as a grounding electrode has existed since the early 1900s. The water industry believes that neutral current flowing on water piping corrodes hte metal. For more information, contact the American Water Works Association about their report—Effects of Electrical Grounding on Pipe Integrity and Shock Hazard, Catalog No. 90702, 1.800.926.7337. Figure 250-105 Mike's Comment from Grounding and Bonding

The way it was explained to our Vo Tech class by a brilliant teacher who was working on his third degree went something like this ( was over 50 years ago ) When current flows thru an underground pipe and comes in contact or even very close to another pipe a small arc could be produced that in time can create holes in pipes. The Ultility companies should be made to feed all of thier distribution transformers with two wires to feed the primary winding whenever a second wire is on the same pole or nearby. Often wondered when a Ultility transformer is only feed with one wire this to me makes it an auto transformer so does this create higher surges during lightning strikes.

 

[electrofelon]

The way it was explained to our Vo Tech class by a brilliant teacher who was working on his third degree went something like this ( was over 50 years ago ) When current flows thru an underground pipe and comes in contact or even very close to another pipe a small arc could be produced that in time can create holes in pipes. The Ultility companies should be made to feed all of thier distribution transformers with two wires to feed the primary winding whenever a second wire is on the same pole or nearby. Often wondered when a Ultility transformer is only feed with one wire this to me makes it an auto transformer so does this create higher surges during lightning strikes.

I frequently state this, but getting rid of the MGN distribution system would not solve current flowing on pipes. By far most current flowing on pipes is because of our grounded premise electrical systems and serving multiple buildings off the same transformer. It would take a dedicated transformer to each building to mostly eliminate the current flow which would be quite expensive for everyone.

 

[mtnelect]

I frequently state this, but getting rid of the MGN distribution system would not solve current flowing on pipes. By far most current flowing on pipes is because of our grounded premise electrical systems and serving multiple buildings off the same transformer. It would take a dedicated transformer to each building to mostly eliminate the current flow which would be quite expensive for everyone.

Could you please explain why there is a grounded connection between the primary and secondary of a utility transformer ?

 

[electrofelon]

Could you please explain why there is a grounded connection between the primary and secondary of a utility transformer ?

First let's note that sometimes there is but not always. It depends on the distribution system. Here in upstate NY the vast majority of distribution is ungrounded Delta. Anyway there are multiple reasons why, when available, the primary neutral would be connected to the secondary neutral. One is to provide a better fault clearing path if a primary falls on a secondary line, or for certain transformer failures like primary to secondary faults. Another is, in the case of an MGN to take advantage of the premise grounding electrodes to keep the primary neutral closer to earth potential. Third it provides a lower resistance for the premises grounding electrode system which could have some advantages in certain situations. Like many things, there are disadvantages too. Personally, I would prefer that this connection NOT exist, I like having isolation between the power company's distribution system.

 

[mtnelect]

First let's note that sometimes there is but not always. It depends on the distribution system. Here in upstate NY the vast majority of distribution is ungrounded Delta. Anyway there are multiple reasons why, when available, the primary neutral would be connected to the secondary neutral. One is to provide a better fault clearing path if a primary falls on a secondary line, or for certain transformer failures like primary to secondary faults. Another is, in the case of an MGN to take advantage of the premise grounding electrodes to keep the primary neutral closer to earth potential. Third it provides a lower resistance for the premises grounding electrode system which could have some advantages in certain situations. Like many things, there are disadvantages too. Personally, I would prefer that this connection NOT exist, I like having isolation between the power company's distribution system.

Thank you, could this also be the reason they combine the grounded and grounding connections on the service drop ?

 

[electrofelon]

Thank you, could this also be the reason they combine the grounded and grounding connections on the service drop ?

I don't understand what you mean. Can you be specific about what you mean by "grounded and grounding connections at the service drop?"

 

[mtnelect]

I don't understand what you mean. Can you be specific about what you mean by "grounded and grounding connections at the service drop?"

On a "Triplex" service drop the utilities attach the grounded conductor to the guy wire which is connected to the service grounding system.

 

[electrofelon]

On a "Triplex" service drop the utilities attach the grounded conductor to the guy wire which is connected to the service grounding system.

Right because the messenger is the grounded/neutral conductor. Perhaps I'm not understanding what you are asking?