Gas pipe bonding. Being used as grounding electrode?

[Kimby]

The situation is a galvanized gas pipe rusted out in this installation. This is a natural gas pipe feed to a gas meter on the other side of the gas meter; (load side) the gas was bonded. The gas was bonded by coming from the ufer ground, then hitting the gas pipe, then going into the meter can (no ground rod was used). Per 2005 250.52 (3) Could the ufer ground have been compromised by the installation of visqueen being used as a vapor barrier under the slab and up the sides of the footer?

The gas pipe, however, instead of going into the house, went back into the ground where it was brought up into the house from the outside (40-50' away) and at different locations, gas cook top, pool heater etc.

The question I have is wether this method caused the gas pipe to become a grounding electrode? The other question, if yes, what code specifically was in violation? 250.52(A)? Another part of the question would be; would these same violations exist for 1999-2005? I know now that galvanized is no longer permitted and the yellow coated stainless is being used.

Last question (if anybody knows), should dieelectric unions have been used at each point of entry out of the ground and into the house? Would this of had any effect?

 

[Dennis Alwon]

Normally the gas company uses dielectric fittings but if the pipe is in the ground for 10 feet or more then it becomes an electrode and dielectric fittings should have been used. Now I don't know whether that would cause the rusting of the pipe. Is that part of your question.

 

[Kimby]

Yes but more specifically shouldn't the gas bond been brought straight to the meter and not part of the ufer ground? Who's responsibility is it to know that the gas line went back into the ground before going into the house?

 

[infinity]

Are you saying that you're using the metal underground gas piping as an electrode? What about 250.52(B)?

250.52(B) Not Permitted for Use as Grounding Electrodes. The following systems and materials shall not be used as grounding electrodes:
(1) Metal underground gas piping systems

 

[Dennis Alwon]

I believe he is saying that the pipe from the utility came to the house but from the load side of the meter the gas line went underground before it came into the house. Now if you bond the pipe as required then isn't the pipe an electrode since there is 40'+ in the ground. Should a dielectric fitting have been used.

 

[ptonsparky]

I do not believe galvanized iron pipe is supposed to be used for gas lines. Should be black iron. For one the galvanizing will flake and ruin the control valves.

 

[Kimby]

The gas pipe was not intended to be electrode. I am asking if by me placing the bond wire in this manner did that cause the gas pipe to become an electrode? If yes is that my fault?

 

[pete m.]

The gas pipe was not intended to be electrode. I am asking if by me placing the bond wire in this manner did that cause the gas pipe to become an electrode? If yes is that my fault?

I dont think it matters if you intentionally ran a bonding jumper to this gas line or not. It is bonded to the GES, by default, through the EGC connected to any of the electrically powered gas fired appliances.

Pete

 

[ptonsparky]

We bond the gas lines much as you have done. We do not intend for them to be a GE but they may very well act as one when the conditions are right. The use of a of a vapor barrier as you describe most likely destroyed or lessend the ability of the rebar to act as a GE. Sounds like adding two ground rods are a minimum.

Dissimilar metals will create a chemical action that can destroy the metals over tiime. Cu and Glavanized iron are two. Add the acidity of the soil and you have a battery which will speed up the process.

Were you responsible for the installation of the gas lines?

 

[Kimby]

No were not responsible for the gas lines but never the less want to know if we are in the wrong? We cannot establish yet wether or not dielectric unions are required by gas code? If they are where are they to be installed?

I know by today's 2008 NEC or the Florida building code many AHJ's do not allows us bond the gas outside any where. I do not know what article of code covers this but I can find out Monday.

MANY THANKS FOR EVERYONES HELP!

 

[Kimby]

Still working on this problem. I will have access to local AHJ's in the am which should help. Meantime, I was wondering if I have interpreted article 250.52(A) correctly.
Last sentence before the exception is written as follows:

Interior metal water piping located more than 1.52 m (5 ft) from the point of entrance to the building shall not be used as a part of the ground electrode system or as a conductor to interconnect electrodes that are part of the grounding electrode system.

If I haven?t taken this out of context, aren?t they implying that the gas/ water pipe cannot be bonded unless it enters the house 5' or closer?

Where does code state that water pipe and gas pipe are treated the same?

Thank you.

 

[Kimby]

250.52(B) Electrodes Not Permitted for Grounding the following shall not be used as a grounding electrode:
(1) Metal underground gas piping system
(2) Aluminum electrodes
Since I was not within 5? of the home per article 250.52(A) did I make this a grounding electrode instead of a bond? Had the pipe entered the home within 5? would I have been ok?
Secondly 250.56 Resistance of Rod, Pipe, and Plate Electrodes
A single electrode consisting of a rod, pipe, or plate that does not have a resistance to ground of 25 ohms or less shall be augmented by one additional electrode of any of the types specified by 250.62(A)(2) through (A)(7).
Should I set up a test to see if I was under 25 ohms without the gas pipe connection? Per 250.56 NEC Handbook 2008 Exhibit 250.25 page 211.

 

[Kimby]

Handbook is 2005 not 2008.

 

[ActionDave]

Kimby, I am trying hard to understand to understand don't know much about building in Florida so please bare with me. It sounds like more than one issue is at play.

Is this a slab on grade house, no crawlspace? I don't know what is done with gas lines in this case. Where I live the gas line cannot enter the house underground, but all the houses have crawl spaces so it is not a problem.

The gas line is not to be part of the grounding electrode system.

If you have visqueen under your footer then you do not have a ufer ground present in the footer.

 

[infinity]

250.52(B) Electrodes Not Permitted for Grounding the following shall not be used as a grounding electrode:
(1) Metal underground gas piping system
(2) Aluminum electrodes
Since I was not within 5? of the home per article 250.52(A) did I make this a grounding electrode instead of a bond? Had the pipe entered the home within 5? would I have been ok?
Secondly 250.56 Resistance of Rod, Pipe, and Plate Electrodes
A single electrode consisting of a rod, pipe, or plate that does not have a resistance to ground of 25 ohms or less shall be augmented by one additional electrode of any of the types specified by 250.62(A)(2) through (A)(7).
Should I set up a test to see if I was under 25 ohms without the gas pipe connection? Per 250.56 NEC Handbook 2008 Exhibit 250.25 page 211.

You cannot use the underground gas pipe as an electrode but you can bond the pipe if you so choose. 250.56 does not apply to a gas pipe or the metallic water pipe either.

 

[norcal]

A metallic gas line buried underground would need to be factory wrapped & the fittings be field wrapped in a approved manner, IF done correctly it should be isolated from the earth....

 

[PEDRO ESCOVILLA]

what the code says is that if the metal water piping ( key here is metal water piping) is more than 5 feet from the service, it can't be used as a GEC. it still has to be bonded, regardless. you can NEVER use gas piping as a GEC, however it must be bonded

 

[PEDRO ESCOVILLA]

p.s. if in doubt about resistance of earth, drive a second ground rod 6 feet from the first. ought to do it anyway

 

[ptonsparky]

what the code says is that if the metal water piping ( key here is metal water piping) is more than 5 feet from the service, it can't be used as a GEC. it still has to be bonded, regardless. you can NEVER use gas piping as a GEC, however it must be bonded

Have a NEC code section supporting that statement?

 

[pete m.]

what the code says is that if the metal water piping ( key here is metal water piping) is more than 5 feet from the service, it can't be used as a GEC. it still has to be bonded, regardless. you can NEVER use gas piping as a GEC, however it must be bonded

You lost me there. Are you saying that you cannot use the water line as a grounding electrode if it is more than 5 feet from the service?

Pete