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170.28.4.4
In Reply to: I am sure city codes vary. Mine would not allow the use of the water line. posted by Norm on March 23, 2007 at 07:59:16:
Your city likely does not allow grounding to the incoming water line for the same reason the NEC now requires a ground rod in addition to the water line connection. The concern is that with today's prevalent use of PVC pipe and water meters with plastic couplings, there is always the chance that continuity between the incoming household water line and city water main could be broken, leaving the home's electrical supply inadequately grounded.
Follow Ups:
Sole water pipe grounds don't make it. This was added to the NEC to eliminate really cheezy construction that was skimping on actually sinking a rod.Of course, water piping should be bonded to elimante touch potential differences. Personally, I also recomend bonding hot and cold water piping at the top of the water heater...
The outside ground rod is called a "supplementary electrode", as per NEC 250.53(D)(2), 250.52(C), 250.56. I believe the use of the word "supplementary" has a clear meaning.Metal water pipes fall under NEC 250.104(A), 250.52(A)(1), and Table 250.66. Connection to the water pipe must be within 5 feet of the breakthrough from the earth, as per NEC 250.52(A)(1).
The instructor who gave the NEC course here two weeks ago, detailed an incident where a homeowner spliced a plastic pipe to the house water feed, and the wife would get a shock in the shower when the dishwasher was on. The dishwasher was energizing the house plumbing, and the homeowner broke the earth connection.. so all those tiny little electrons found a path the the earth by travelling from the showerhead through the poor wife, to the shower drain with it's copper pipe to the earth.
Where I live, both pipe and grounding electrode are now required on all new installs and service upgrades. They do not allow just one or the other. Old installs are grandfathered.
If anybody is interested in this stuff, I highly recommend Stallcup's Electrical Design Book, author James Stallcup Sr, Jones and Bartlett publishers, 2005. Well written, it details such things as I have posted, with drawings and references to the applicable NEC code section.
However, I still recommend all consult a qualified electrician or inspector..
Cheers, John
Incorrect. It's actually dealing with wall penetration of a building regarding metallic water piping."Supplemental" and "supplementary" are not Art 100 defined; regarding grounding. The brief on all this is that water pipe grounding alone doen't cut it for a residential service.
There is *so much info missing from the (unregistered) OP, it's hard to make a judgement. The original premise is flakey from the git-go...it's impossible to comment w/o a set of as-built drawings on just what the system consists of.
nt.
In Stallcup's Electrical design Book, page 11-39, it specifically states "supplementary electrode". THAT is where I got it.You are probably looking it up in the NEC...which of course, is no fair...:-( I don't have a copy..:-(
I am confident you are correct...it is probably as you said...
What I like about Stallcup's book is it provides diagrams and shows exactly what code references apply...even if he doesn't use the exact words..
He is rather unbelievable, however..he knew NEC better than I know the back of my hand...it was amazing.
Course, I believe he chaired the chapter 4 NEC committee..
Cheers, John
I thought maybe you meant Supplemental......NEC 250.53 (D)(2) talks about Supplemental Electrodes required.
Page 70-102250.54 speaks of Supplementary Grounding Electrodes. This is new for 2005 NEC. Page 70-103
All I had to go by was what was in Stallcup's.Is there a difference between supplemental and supplementary?? (If I had the 2005 NEC, I wouldn't hafta ask..)
Is there a difference between supplemental and supplementary?? (If I had the 2005 NEC, I wouldn't hafta ask..)Yes, all of the sections you quoted in your post about Grounding Electrodes was right on the money.
250.53 (D) (2) is indeed the section for, "Supplemental Electrode Required", as stated in your post.
===================================
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250.54 Supplementary Grounding Electrodes, is a new section added to article 250, for NEC 2005.quote:
"250.54 Supplementary Grounding Electrodes. Supplementary grounding electrodes shall be permitted to be connected to the equipment grounding conductors specified in 250.118 and shall not be required to comply with the electrode bonding requirements of 250.50 or
250.53(C) or the resistance requirements of 250.56, but the earth shall not be used as an effective ground-fault current path as specified in 250.4(B)(4)."
==================NEC 2005 is full of changes and additions over NEC 2002.
Hi Jim-*If* it's adopted, this will be mind boggling in it's scope and scale.
(I think I have 5-8-5 correct, since I'm at home.)585 will be COPS; Critical Operating Power Systems. This will be huge; and extends the reach of the NEC far beyond initial design parameters; and I do mean far.
s
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