current on the water pipe GEC

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electricalperson

electricalperson

Senior Member
Location
massachusetts
i 100% believe a couple amps is perfectly normal to have on the GEC water pipe if the water pipe system is all metal. i believe its caused because the neutral is pretty much in paralell with the water pipe so current is finding the pipe as another path to go down.

some people believe current on the water pipe is a problem

how many people here agree with me?
 
quogueelectric

quogueelectric

Senior Member
Location
new york
electricalperson said:
i 100% believe a couple amps is perfectly normal to have on the GEC water pipe if the water pipe system is all metal. i believe its caused because the neutral is pretty much in paralell with the water pipe so current is finding the pipe as another path to go down.

some people believe current on the water pipe is a problem

how many people here agree with me?
Click to expand...
I believe small amounts of current on the water pipe is ok. Large amounts and in the wrong direction is NOT ok.
 
iwire

iwire

Moderator
Staff member
Location
Massachusetts
electricalperson said:
i 100% believe a couple amps is perfectly normal to have on the GEC water pipe if the water pipe system is all metal.
Click to expand...

I agree it is normal but the amount of current can range of a few amps to many amps, it will always be a percentage of the unbalanced neutral current so if you have high unbalanced neutral current GEC current will also be high.
 
peter d

peter d

Senior Member
Location
New England
Yes, basically you have a current divider. My guess is that most of the current should be carried by the wire conductors because they will have lower impedance than the water piping system, which may have a questionable impedance (GEC to water pipe connections for instance.) I'm only speculating though. :)
 
iwire

iwire

Moderator
Staff member
Location
Massachusetts
Lets say your GEC connection and those of your neighbors are good and are interconnected with copper water lines.

Which do you think will have more impedance, good sized copper tubbing or the skinny neutral of your overhead drop?

I think Don has mentioned 40% of the current flowing on the GEC would not be surprising.
 
peter d

peter d

Senior Member
Location
New England
iwire said:
Lets say your GEC connection and those of your neighbors are good and are interconnected with copper water lines.

Which do you think will have more impedance, good sized copper tubbing or the skinny neutral of your overhead drop?

I think Don has mentioned 40% of the current flowing on the GEC would not be surprising.
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Well, obviously the wire has lower impedance because 60% of the current is flowing on it. ;)
 
V

Volta

Senior Member
Location
Columbus, Ohio
One nice thing about current on a fully connected water piping system is that it can save equipment from damage when the neutral gets pulled out in a windstorm.
It might take a while for an occupant to realize there is a problem though.
That would be a great time for the neighbor's plumber to have jumper cables.
 
R

realolman

Senior Member
Help me out here... I'm trying to envision the reason for a couple amp current flow from my electrical panel, to the water pipe, to where ... through what?

And I'm not being a wise guy. Maybe a dumb guy.
 
brian john

brian john

Senior Member
Location
Leesburg, VA
realolman said:
Help me out here... I'm trying to envision the reason for a couple amp current flow from my electrical panel, to the water pipe, to where ... through what?

And I'm not being a wise guy. Maybe a dumb guy.
Click to expand...


In a commercial building it is more likely through a ground on the neutral down stream of the main service neutral ground bond. You are setting up a parallel path with anything metallic in the building and the neutrals.

In a residence one of the more common situations is with a utility metallic water distribution shared by all neighbors and you are on the same transformer. Each service in the residence is grounded to the cold water pipe. You have set up a parallel path with the neutral and water pipe. Just passing current from the neutral to the water pipe and back as it is all returning to the utility transformer.

In my experience 1 or 2 amps in not all that uncommon. BUT I recommended investigating all current on cold water pipes to determine the source.
 
R

realolman

Senior Member
Me and the neighbors on the same transformer.... that went right over my head.... or right through it.:smile:
 
I

ibew501ed

Senior Member
Location
danbury ct/work in white plains ny
I believe he means current leaving your house on the water pipe seeking its source in parallel with your neutral (groundED conductor) OR current entering your house ( from your neighbors house that lost their neutral) seeking ITS source via your neutral connection to the poco transformer
 
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