Is grounding to plumbing ok?

[Mike 870]

I had 2 outlets by my kitchen sink. Neither were grounded or GFI.  I put in GFI outlets and snaked a ground wire up to the box and used a grounding clamp to ground them to the plumbing.  They test correct on the tester.  Is this a code no no?

[fraggin]

http://www.copper.org/consumers/copperhome/Electrical/wiring_electrical_groundrules.html

[Mike 870]

hmm that was not very clear.  My electrical systm is grounded with a grounding rod.  I assume my plumbing is part of that grounding system since it passed inspection when the panel was upgraded from fuzes.  I don't have any plastic pipe either.

[fraggin]

I think that's what the NEC code stands for. Never Exactly Clear.

[Mike 870]

Ha Ha, thanks.  The guy at home depot said it was ok, but figured I'd check.  I suppose I will find out soon enough as I have a home inspector going through today.

[John Raabe]

It is my understanding that what you have done is correct. But then I'm neither a plumber or an electrician.

[MountainDon]

Around here grounding to water pipes does not count; they require an 8 foot copper clad ground rod. Even on the few homes that have copper piping.


Does that GFCI unit trip ok when tripped with an external test device, not the test button on the GFCI?

[cordwood]

 One thing to consider with using plumbing for a ground,....Electrolysis! Your pipes have enough trouble with minute current running through them without adding to it.

[Mike 870]

Don, yes they test "correct wiring" with the 3 prong tester you plug into the outlet to test them.  The GFI light also comes on and off when I push test and reset. 

Cordwood, I dont know what Electrolysis is, is it something to be worried about?

From what I have heard from other sources what I have done is safe.  It's just a matter of if the inspector takes offense.  I had one inspection today, and have another on the 11th.  Today's inspection went ok.

[MountainDon]

True electrolysis, or electrolytic corrosion to be more correct happens with DC currents, not AC. It's the same principle used in electrplating one metal on another.

What cordwood is referring to should be more correctly called galvanic or dissimilar metal corrosion. Galvanic corrosion is caused by self-induced current created by electrical potential of two dissimilar metals in contact with an electrolyte. It can occur when two dissimilar metals (such as copper tube and steel pipe) are connected in the presence of an electrolyte.

Fresh potable water is a weak electrolyte. Salt water or acid solutions are good electrolytes, hence the use of an acid solution in an automotive battery. Furthermore, based on common metal piping materials and how they react to each other, it is rarely the copper tube that fails because of galvanic corrosion.

Buried copper pipe on the hand does fail in certain soils. Glenn knows all about that.

I don't think you will have much danger of the pipes (copper?) deteriorating with your simple grounding of a couple of outlets.

[Mike 870]

Thanks for the advice and data Don.  What I can't understand is why they didn't ground these 2 outlets when they updated the panel.  Every other outlet in the house is grounded except these two, and they are by water to boot.  It ticks me off that it passed inspection this way too, but now I have to worry about it.  It wasn't that hard for me to snake the wire from the basement up to the box, and they could have easily just snaked a new wire and grounded it correctly to the panel.  I took the short cut because I didn't want to mess with the panel.

[MountainDon]

If you could snake another wire to another box that is grounded back to the panel you could connect there instead of the water pipe.

[Redoverfarm]

Chance are really remote but what would happen if someone was washing dishes or their face and a short occurs and follows the ground.   

[fraggin]

You think that's bad, I once worked on a phone system where the initial symptoms were, "at random calls were dropped and the phone system would go into alarm mode." I took a better part of a week to discover the ground was connected to a water main via a waterhose clamp. When renovations to other floors were being made, a pvc connection was introduced into this tech's 'ground'. Not the best material to carry current.

[John Raabe]

My assumption was that you do have the plumbing grounded with a rod. Is that not the case? That may be all you need to do (your inspector will know).

[cordwood]

True electrolysis, or electrolytic corrosion to be more correct happens with DC currents, not AC. It's the same principle used in electrplating one metal on another.

What cordwood is referring to should be more correctly called galvanic or dissimilar metal corrosion. Galvanic corrosion is caused by self-induced current created by electrical potential of two dissimilar metals in contact with an electrolyte. It can occur when two dissimilar metals (such as copper tube and steel pipe) are connected in the presence of an electrolyte.

Fresh potable water is a weak electrolyte. Salt water or acid solutions are good electrolytes, hence the use of an acid solution in an automotive battery. Furthermore, based on common metal piping materials and how they react to each other, it is rarely the copper tube that fails because of galvanic corrosion.

Buried copper pipe on the hand does fail in certain soils. Glenn knows all about that.

I don't think you will have much danger of the pipes (copper?) deteriorating with your simple grounding of a couple of outlets.

Electrolysis is not the correct term but is widely used to describe the damage.
AC or DC will cause it. Anytime you mix water/metal/current you can get corrosion at joints or anywhere the current wants to seek a bridge. Soil or concrete can supply the needed ingredients for corrosion. Even a semi trucks frame can be turned to junk by using it for a ground in wet conditions. I have seen way too many Freightliners with aluminum frames that were eat up from the factory not grounding the battery to the block but using a welded stud on the frame. When we changed the ground wire the problem stopped.
I prefer a dedicated wire weather it be 12 volts DC or 220 volts AC. But that's just me.

[Mike 870]

I am fairly certian the plumbing is grounded with a rod.  I attached some pictures that show why I think my plumbing is grounded.

Don I considered doing what you suggested, however I wasn't confident enough to try that.

Water in


same copper ground wire travels to electric panel


ground wire travels out of panel & out of house where I can see the top of a ground rod

[Mike 870]

In reply to redover, that's pretty much why I put in the GFI outlets and also grounded them.  Before I did this, there were normal 15 amp outlets, with no ground at all.  I was under the impression that even without a ground the GFI outlets will still trip if there is a surge.  I grounded them just to be safe. 

Also to be clear, the pictures above are not of what I did.  They are only to show why I think my plumbing is grounded via rod.

[MountainDon]

GFCI's will trip even if there is no ground.

However, you are safer if there is a ground connection as well.

[cordwood]

 I only put one GFI in my kitchen and wired the others through the back of it. I don't know if all can be done that way but all the ones I have used have been that way. Anything wired through them down line was protected.

[MountainDon]

That is the way to do it cordwood. Going by the NEC all the downstream outlets are supposed to have a label indicating they are protected, though I have not seen any marked as such.

[Mark L.]

I have seen a lot of wiring grounded to plumbing, in fact i live in a house that's that way. Its fine now, but someday if someone comes in and replaces a piece with plastic pipe, pvc or pex, you no long have a real ground through the metal. Water lines would most likely be fine but plumbing could be iffy.

[Mike 870]

I guess I should clarify, it's grounded to a water line in the basement, not a drain.