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Old 06-01-2010, 06:45 PM   #1
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Planning "above code" bonding/grounding system


Hello all,

I am planning on installing an "above code" bonding/grounding system in my home (built 1982) for a couple reasons:

1. To ensure safety in cases where the home's metalic piping or ductwork is accidentally energized due to a ground fault.
2. To ensure any induced energy in the home's metalic piping or ductwork due to a nearby lightning strike is dissipated and has an easy path to ground.

So, here is my plan:

1. Run 6 AWG bare copper wire from the exposed HVAC ductwork and 4 AWG bare copper wire from the water line to a 1/4" copper bus bar.
2. Run 4 AWG bare copper from the copper bus bar to the grounding/grounded bus in the main (100 amp) service panel.
3. Install a whole-home TVSS at the service panel, with good quality surge suppressors at point-of-use.
4. At a future date, upgrade the home's grounding electrode system (currently, only one electrode of unknown depth) with a system similar to the one described Rex Caudwell's "Wiring a Home" (multiple 8' ground rods continuously connected with 4 AWG bare copper to the main service panel).

My questions concerning this:

1. Should I also bond the natural gas pipe to the copper bus bar? I know bonding the natural gas line is a contentious subject.
2. Is the NEC violated by having the bond between the service panel and the water line discontinuous (i.e. going through the copper bus bar)?

Thanks for any input. Please let me know if a sketched diagram would be helpful here.
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Old 06-01-2010, 07:17 PM   #2
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#1 IMO, the natural gas pipe will be grounded through gas apliences, so why not ground the pipe?

#2, no idea, but on a related mater, how do you ground the water pipe if you run PEX?
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Old 06-01-2010, 07:56 PM   #3
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You don't ground the pipe. If there is a metallic water pipe entering the house you install a grounding electrode conductor to the pipe from the electrical panel to within 5' of where the pipe enters the structure.

Bonding of the gas piping may or may not be required by the AHJ. NEC says the equipment grounding conductor to the appliance is sufficient.

CSST must absolutely be bonded as per the manufacturer.

Last edited by brric; 06-01-2010 at 08:01 PM.
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Old 06-02-2010, 08:46 AM   #4
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Given the age of your house, all of the items should already be properly grounded and/or bonded unless improper modifications or additions have been made.

The addition of the surge protection is the only item not typically installed you would need to add.
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Answers based on the National Electrical Code. Local amendments may apply. Check with your local building officials.
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Old 06-02-2010, 11:44 AM   #5
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Quote:
Originally Posted by Jim Port View Post
Given the age of your house, all of the items should already be properly grounded and/or bonded unless improper modifications or additions have been made.

The addition of the surge protection is the only item not typically installed you would need to add.
Jim, thank you for your input. I'm sure the home is "to code" for 1982, but my experience has been that code isn't adequate for today's sensitive electronics, of which I have too many. Plus, I am an electronics geek, and doing projects like this is a good way for me to learn. I just want to make sure it's done right. It's probably a waste of money, but I find it enjoyable.

That being said, I found a web page (http://ecmweb.com/grounding/electric..._vs_bonding_7/) which seems to indicate that the busbar method is acceptable. Any disageement?

Also, commenter brric mentioned that the bond to the cold water pipe must be within 5' of the pipe's entrance into the home. Currently, the electrical panel is bonded to the cold water pipe approximately 25' away from where the pipe it enters the home, and then only using braided copper wire (unsure of the size). If I wanted to bring this up to current code, should I run new solid copper wire from the panel to where the water pipe enters the home? This would be sized per 250.66, correct?

Thanks again!
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Old 06-02-2010, 11:51 AM   #6
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Quote:
Originally Posted by mac007 View Post
Also, commenter brric mentioned that the bond to the cold water pipe must be within 5' of the pipe's entrance into the home. Currently, the electrical panel is bonded to the cold water pipe approximately 25' away from where the pipe it enters the home, and then only using braided copper wire (unsure of the size). If I wanted to bring this up to current code, should I run new solid copper wire from the panel to where the water pipe enters the home? This would be sized per 250.66, correct?
Actually it's the other way around. The piping is bonded to the panel. Semantics I agree, but accuracy means something.

If the pipe entering the home is metallic then it must be connected within 5'. If the piping entering the home is non-metallic then the wire is simply a water bond and the connection can be made anywhere accessible.
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Old 06-02-2010, 11:58 AM   #7
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Quote:
Originally Posted by Speedy Petey View Post
Actually it's the other way around. The piping is bonded to the panel. Semantics I agree, but accuracy means something.

If the pipe entering the home is metallic then it must be connected within 5'. If the piping entering the home is non-metallic then the wire is simply a water bond and the connection can be made anywhere accessible.
If the pipe is metallic entering the home it should be used as a grounding electrode. It is NOT merely bonded.
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Old 06-02-2010, 06:15 PM   #8
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In my jurisdiction (Chicago) bonding of gas pipe is required. In high rise construction here we have what is referred to as a Hogan Ground. Basically it consists of what you describe and in essence is bringing the GEC all the way through the building via a 500 kcmil cable bonded to a busbar at every floor. This allows the code required bonding at intervals without taking everything to the basement. Here we bond building steel, ductwork, sprinkler pipes, gas pipes and low voltage raceway.

I think your system sound alright, albeit excessive for a residential setting. If you're concerned about lightning, perhaps a lightning suppression system would be in order.
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Old 06-02-2010, 07:58 PM   #9
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Quote:
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If the pipe is metallic entering the home it should be used as a grounding electrode. It is NOT merely bonded.
That's what I said.
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Old 06-02-2010, 10:06 PM   #10
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I think your system sound alright, albeit excessive for a residential setting. If you're concerned about lightning, perhaps a lightning suppression system would be in order.
Go big or go home I always say. My lightning concern is only for the induction caused by an occasional nearby strike, as I don't think any system can stand up to a direct hit. But a lightning protection system might be a "Step 5" in my plan ... someday.

Quote:
Originally Posted by brric View Post
If the pipe is metallic entering the home it should be used as a grounding electrode. It is NOT merely bonded.
Yep, and that's why I'm sizing the conductor to the water line per 250.66, not 250.122 (see 250.104(b)). I'm understanding the NEC correctly on this, yes? I apologize for interchanging the terms "grounding" and "bonding" above.

Thanks again to everyone for the advice and info. Much appreciated!
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Old 06-03-2010, 06:02 AM   #11
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Yep, and that's why I'm sizing the conductor to the water line per 250.66, not 250.122 (see 250.104(b)). I'm understanding the NEC correctly on this, yes?
250.104(b) does not apply to water piping. It is used for "Other Metal Piping".

250.104(A) is the section for "Metal Water Piping".
The connection to water piping, whether used as an electrode or not, must be sized according to T250.122. The only difference is where it is required to be connected.
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Old 06-03-2010, 09:02 AM   #12
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Quote:
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250.104(b) does not apply to water piping. It is used for "Other Metal Piping".
Yes, this is what I meant. Sorry if it wasn't clear.

Quote:
Originally Posted by Speedy Petey View Post
250.104(A) is the section for "Metal Water Piping". The connection to water piping, whether used as an electrode or not, must be sized according to T250.122. The only difference is where it is required to be connected.
You sure about that? 250.104(a)(1) clearly states: "Metal water piping system(s) installed in or attached to a building or structure shall be bonded to the service equipment enclosure, the grounded conductor at the service, the grounding electrode conductor where of sufficient size, or to the one or more grounding electrodes used. The bonding jumper(s) shall be sized in accordance with Table 250.66 except as permitted in 250.104(A)(2) and (A)(3)." (My emphasis.) The exemptions in 250.104(a)(2) and (a)(3) don't seem to apply to me, as they relate to multiple occupancy buildings and multiple buildings supplied by feeders/branch circuits, respectively.

I'm looking at the 2008 NEC.
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Old 06-03-2010, 07:57 PM   #13
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You sure about that?
Nope.
You are correct. Brain fart on my part. I was going by memory and did not re-read the whole thing. Sorry.
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Old 06-04-2010, 11:15 AM   #14
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Nope.
You are correct. Brain fart on my part. I was going by memory and did not re-read the whole thing. Sorry.
No problem. Thanks again!
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