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#1029 - 04/14/01 05:26 AM Ground faults and non-metallic plumbing supply  
Phil H  Offline
Member
Joined: Apr 2001
Posts: 21
Tujunga, CA
I'd like to start by telling you that I am not an electrician, so my terminlogy and knowledge is not up to speed.

In a dwelling that has metal waterpipes used for or connected to the grounding electrode , are metal plumbing fixtue supply lines significantly safer than flexible plastic supply lines which are commonly installed. I realize that a functioning GFCI would provide protection, but how many people test GFCIs and what about locations where GFCIs are/were not required. Is the water itself considered a good enough conductor to effectively trip a typical breaker or fuse. This is not something I care to experiment with.

thanks in advance for any insight
Phil H


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#1030 - 04/14/01 07:54 AM Re: Ground faults and non-metallic plumbing supply  
Tom  Offline
Member
Joined: Jan 2001
Posts: 1,044
Shinnston, WV USA
Phil,

You're right about people not testing GFI receptacles. One survey showed that about 18 or 19% of GFI's no longer provide GFI protection.

The water would not be a good enough conductor to cause a breaker to trip or a fuse to blow, but it would probably allow enough current flow to get someone killed if the GFI doesn't function.

Tom


Few things are harder to put up with than the annoyance of a good example.

#1031 - 04/17/01 10:56 AM Re: Ground faults and non-metallic plumbing supply  
SlamTex  Offline
Member
Joined: Apr 2001
Posts: 53
I'm not really sure what your question is pertaining to, but I will offer some advise. If you are worried about the equipment (noncurrent carrying metal portion) in your house becoming energized, then you need to ensure the equipment has an "equipment grounding conductor" that runs all the way back to the service equipment. If you are worried about your GFI receptacles not working properly, set up a maintenance schedule for your home, and check them from time to time. I actually check GFI's every time I plug into one (must be an electrician's habit). I would suggest hiring an electrical contractor in you area to check out your home. It is difficult to understand your problem without seeing it with my own eyes. If you insist on "doing it yourself" (I understand) then I would suggest that you go buy a book that will help you with basic residential wiring. You also need a thorough knowledge of Article 250 of the NEC. In my opinion, grounding is the most important subject in the electrical industry (it is what saves your life, or keeps your house from burning down in a fault condition). I could also tell you many stories of improper wiring causing problems. Good Luck, and God Bless!

HMEL #688


#1032 - 04/17/01 02:35 PM Re: Ground faults and non-metallic plumbing supply  
wayne  Offline
Member
Joined: Apr 2001
Posts: 54
NC
Phil if I understand you right about the metal verses the plastic hook up to the fixtures insofar as being safer one over the other. My answer is that if the service is properly grounded including the equiment grounding conductor. there are no difference.In a residential dwelling where there are metal water piping the nec req us to run a EGC within 5' of the service.

Far as the GFCI are concerned everyone should check those on a regulary monthy basis.
Wayne


#1033 - 04/17/01 09:49 PM Re: Ground faults and non-metallic plumbing supply  
Phil H  Offline
Member
Joined: Apr 2001
Posts: 21
Tujunga, CA
Thanks for the replies. I guess I was not very clear. My thinking was that metallic plumbing supply lines which connect a faucet to the household plumbing could bond the faucet to the grounding system whereas the plastic hoses most commonly used would not. I assumed a bonded fixture would be somewhat safer but I was not certain. A thread in the theory section, "path of least resistance" also provided me with some insight.

Only intuition told me that it could be safer but now more than ever I am uncertain. If I am not mistaken, a metal sink and or faucet installed within 5 feet of a whirlpool tub would be bonded but if the tub was not a whirlpool it would not need to be bonded. My convoluted logic is that if it's good for a lav by a whirlpool why not one next to a regular tub or any sink. Or is the whirlpool requirement only for a bonding grid which is completely different than attaching to the grounding system (stabilize or eliminate voltage gradients rather than provide fault protection).

Thanks again for the replies. I think I am just thinking about this too hard. By the way, I am going to replace the supply lines for all of the sinks and toilet in my house and I was considering using soft copper tube tube. Not that it matters. The all metal waterpipe is the grounding electrode; adding a supplemental rod etc. will come when other electrical is upgraded in this older house.

Phil H


#1034 - 04/17/01 10:04 PM Re: Ground faults and non-metallic plumbing supply  
Bill Addiss  Offline
Member
Joined: Oct 2000
Posts: 3,878
NY, USA
Phil,

Let me take a stab at this, These are my opinions, (others - please correct me if I am wrong!!)

I think the answer to your question depends on the situation.
Quote
In a dwelling that has metal waterpipes used for or connected to the grounding electrode , are metal plumbing fixtue supply lines significantly safer than flexible plastic supply lines which are commonly installed.


First, a GFCI (if working) will help protect from harmful shocks.

Aside from that, (No or non-working GFCI) if you're talking about a live conductor making contact with the Sink, Tub, or Plumbing fixture itself the supply would have to be metallic to make the Breaker trip. I don't think that the water itself would permit enough current flow to trip a breaker.

(The current flow would depend upon the ammount and type of impurities in the water, as pure water is actually an insulator)

In a situation where you (a person) come into contact with a live wire or get some leakage and are touching the Sink, Tub, or plumbing Fixture, it would be a bad situation but probably be best for you if the supply connections were not metallic. But that might be different if you were actually in the Tub.

In short, after all this, I would have no recommendations except to install and test GFCI's on a regular basis and use common sense when it comes to 'water and electricity'

Bill



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