Gas Pipe grounding Vs. Bonding

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Receptive

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Hey guys and gals!

New to the site and wanted to post a question for you all.

According to the 02' code book (I know, I need to get the 05' or 08' but I am sure it is still the same verbage), Article 250.52 (B)(1) Metal underground gas piping systems are not permitted as grounding electrodes.

Also in Article 250.104(B) Gas piping is required to be ("shall be") bonded to the service equiptment enclosure, the grounded conductor at the service, the grounding electrode conductor where of sufficient size, or to the one or more grounding electrodes used.

In a way these two seem to contain a contradiction but I may need some clarification on how to interpret what is being stated here.

My question is simply if one is allowed to bond the gas piping system to one of the grounding electrodes, doesn't that - at least mechanically make it part of the grounding electrode system? I assume that the code means to eliminate the gas piping system as being the only grounding electrode or as the supplimental. For instance, having the underground water and gas piping systems serve as the GES.

Does anyone know the reasons why the gas piping system is not permitted to be a GE?


Thanks
 
welcome to the Forum. I think you will find the key is with the word "interior". The requirement is to bond "interior" gas piping. In most systems the gas utility installs a dielectric union that electrically separates the underground pipe and the interior pipe so in bonding the interior pipe you are not bonding the underground pipe.
 
In most locations now, the gas line ran underground is plastic, at least here it is, so the GES issue is not a problem, it not there should be a dialectic union to break the connection, the NEC only requires a gas pipe to be bonded, if it "may become energized", and is also allowed to be bonded via the equipment grounding conductor of the equipment that will most likely energize it, so for the most part, if the gas pipe is solidly connected to a furnace, and the furnace is bonded to the EGC of the circuit feeding the furnace, then it is bonded as far as the NEC goes.
Read all of 250.104(B)

But if the gas pipe is of the CSST type, then the manufacture (not the NEC) will have instructions to bond the gas pipe at where the pipe enters the building.
 
Receptive said:
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Also in Article 250.104(B) Gas piping is required to be ("shall be") bonded to the service equiptment enclosure, the grounded conductor at the service, the grounding electrode conductor where of sufficient size, or to the one or more grounding electrodes used.
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This is not a true statement.
 
electricmanscott said:
This is not a true statement.
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I beg to differ.

250.104(B) Other Metal Piping. Where installed in or attached to a building or structure, a metal piping system(s), including gas piping, that is likely to become energized shall be bonded to the service equipment enclosure, the grounded conductor at the service, the grounding electrode conductor where of sufficient size, or the one or more grounding electrodes used. The bonding jumper(s) shall be sized in accordance with 250.122, using the rating of the circuit that is likely to energize the piping system(s). The equipment grounding conductor for the circuit that is likely to energize the piping shall be permitted to serve as the bonding means. The points of attachment of the bonding jumper(s) shall be accessible.
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And welcome Receptive.
 
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Now I'll highlight the parts that spin it my way. :grin:


250.104(B) Other Metal Piping. Where installed in or attached to a building or structure, a metal piping system(s), including gas piping, that is likely to become energized shall be bonded to the service equipment enclosure, the grounded conductor at the service, the grounding electrode conductor where of sufficient size, or the one or more grounding electrodes used. The bonding jumper(s) shall be sized in accordance with 250.122, using the rating of the circuit that is likely to energize the piping system(s). The equipment grounding conductor for the circuit that is likely to energize the piping shall be permitted to serve as the bonding means. The points of attachment of the bonding jumper(s) shall be accessible
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This is entirely different than what the op posted

Receptive said:
Also in Article 250.104(B) Gas piping is required to be ("shall be") bonded to the service equiptment enclosure, the grounded conductor at the service, the grounding electrode conductor where of sufficient size, or to the one or more grounding electrodes used.
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I stand by what I said. The prior is not true.
 
chris kennedy said:
I beg to differ.

250.104(B) Other Metal Piping. Where installed in or attached to a building or structure, a metal piping system(s), including gas piping, that is likely to become energized shall be bonded to the service equipment enclosure, the grounded conductor at the service, the grounding electrode conductor where of sufficient size, or the one or more grounding electrodes used. The bonding jumper(s) shall be sized in accordance with 250.122, using the rating of the circuit that is likely to energize the piping system(s). The equipment grounding conductor for the circuit that is likely to energize the piping shall be permitted to serve as the bonding means. The points of attachment of the bonding jumper(s) shall be accessible.
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And welcome Receptive.
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I would also say it was not totally true since it only picked out a part of 250.104(B)

Stopping here:
Other Metal Piping. Where installed in or attached to a building or structure, a metal piping system(s), including gas piping, that is likely to become energized shall be bonded to the service equipment enclosure, the grounded conductor at the service, the grounding electrode conductor where of sufficient size, or the one or more grounding electrodes used. The bonding jumper(s) shall be sized in accordance with 250.122,
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would make it look like we have to bond the gas pipe, and we would have to use table 250.122 sized per the service, which we should know is not true, and I have had inspectors do this very same thing, but we must include the rest of 250.104 to see the whole picture:

using the rating of the circuit that is likely to energize the piping system(s). The equipment grounding conductor for the circuit that is likely to energize the piping shall be permitted to serve as the bonding means. The points of attachment of the bonding jumper(s) shall be accessible.
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so now we see yes we have to use table 122, but at the size of the circuit that might likely energize it, and the allowance to just use the EGC of that circuit. so if it already bonded via this EGC then we are done.:D
 
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electricmanscott said:
If the piping is likely to become energized, this means it is pretty much assured that it going to happen, you have more to worry about than the egc size. :)
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Yea some really bad wiring.

had a gas meter guy get shocked off a meter, before from a bad utility neutral, but no bonding in a house will solve that.:roll:

I ment "not totally true" in my last post. I edited it.:D
 
electricmanscott said:
This is not a true statement.
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Yes I did not quote the entire article which does lead to misinterpreting what it means.

If what augie47 and hurk27 mentioned about the nature of the underground gas piping system is true then it makes sense not to use the it as the GE. Without electrical conductivity how could it serve as an effective GE?

"Likely to be energized" is being overriden in my area with "Will be energized no matter where it is" so we are being required to bond the gas piping system where it enters the house at the closest location to the service or ground rod and at the water heater between the cold water and the gas pipe using the same sizing of the gec ( I.e. #4 sheilded for 200amp service)

K8MHZ: I agree about the difference between grounding and bonding. I just couldn't figure out what made the gas piping system unsuitable as a GE.
 
electricmanscott said:
If the piping is likely to become energized, this means it is pretty much assured that it going to happen, you have more to worry about than the egc size. :)
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The only issue is the fact that CMP 5 does not read the word "likely" like you and I do.
In older codes the wording was "may become energized". Panel 5 says that the terms "may become energized" and "likely to become energized" mean exactly the same thing. If they would revert back to the term "may become energized", then it would be clear that all gas piping would have to be bonded. It is the panel's intent, even with their poor choice of wording, that all gas piping be bonded.
 
don_resqcapt19 said:
The only issue is the fact that CMP 5 does not read the word "likely" like you and I do.
In older codes the wording was "may become energized". Panel 5 says that the terms "may become energized" and "likely to become energized" mean exactly the same thing. If they would revert back to the term "may become energized", then it would be clear that all gas piping would have to be bonded. It is the panel's intent, even with their poor choice of wording, that all gas piping be bonded.
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Well that would not make sense as the removal of "may become energized" and or "likely to become energized" would remove all doubt that the gas pipe has to be bonded if that was their intent?

what if the gas pipe ran into a non electric-fire place from the outside, and was not used anywhere else or entered the building, from the term "likely to become energized" I would say there is an allowance , that the gas pipe would not have to be bonded since it is not likely to become energized?

And why woudn't the wording be more like that which is for water piping in 250.104(A)????
 
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don_resqcapt19 said:
The only issue is the fact that CMP 5 does not read the word "likely" like you and I do.
In older codes the wording was "may become energized". Panel 5 says that the terms "may become energized" and "likely to become energized" mean exactly the same thing. If they would revert back to the term "may become energized", then it would be clear that all gas piping would have to be bonded. It is the panel's intent, even with their poor choice of wording, that all gas piping be bonded.
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It may be the intent but it certainly isn't what they said. :)
 
I've always wondered about CST. If the concern is the CST being subject to fault current, it would seem they'd want the flexible section bypassed. Or, they'd want the "load" end of the flex bonded back to the service (also effectively bypasing the flex.)

However, what I've been told has to be done is to place a bond between the gas entrance and the service ground, which I would think should have been done when the building was first built, even before the CST was added to serve a new appliance.
 
In the older section of our small town, all gas meters are in the alley. Piping is all metal. From meter to house can easily be 50'+. I bonded the piping in the house with a #6. I did not use it as a grounding electrode. That is what the 3 ground rods were for. The gas meter and piping is within 2 feet of the pole ground in the alley. Any one care to guess which one is likely to handle more current?
 
Tom,
I think that you will find that the gas company used a dielectric fitting on the street side of the meter to provide electrical isolation between the underground supply piping and the bonded interior piping.
 
don_resqcapt19 said:
The only issue is the fact that CMP 5 does not read the word "likely" like you and I do.
In older codes the wording was "may become energized". Panel 5 says that the terms "may become energized" and "likely to become energized" mean exactly the same thing. If they would revert back to the term "may become energized", then it would be clear that all gas piping would have to be bonded. It is the panel's intent, even with their poor choice of wording, that all gas piping be bonded.
Click to expand...

It does seem that if there is any electrical wiring running through the walls of a building whether vertically or horizontally through framing members, and the gas piping system enters through such a wall that there is a possiblility of it becoming energized through any number of reasons. And if, by chance, a live wire in such a wall does come in contact with the gas piping system then it is likely to become energized. To me, it seems that the intent is that the entire gas piping system is to be bonded.

Also, though, it seems to me that if the gas piping is run to a detached garage in such a manner that it would be impossible for the gas piping to become energized by the electrical circuits inside then there would be no need for bonding of the gas piping sytem at the garage.
 
don_resqcapt19 said:
Tom,
I think that you will find that the gas company used a dielectric fitting on the street side of the meter to provide electrical isolation between the underground supply piping and the bonded interior piping.
Click to expand...


I watched/helped the gas utility, remember small town, connect the pipe to my house after we put new footings under it. There is no dielectric fitting at the house. Most likely one at the meter...50'+ away.
 
Receptive said:
It does seem that if there is any electrical wiring running through the walls of a building whether vertically or horizontally through framing members, and the gas piping system enters through such a wall that there is a possiblility of it becoming energized through any number of reasons. And if, by chance, a live wire in such a wall does come in contact with the gas piping system then it is likely to become energized. To me, it seems that the intent is that the entire gas piping system is to be bonded.

Also, though, it seems to me that if the gas piping is run to a detached garage in such a manner that it would be impossible for the gas piping to become energized by the electrical circuits inside then there would be no need for bonding of the gas piping sytem at the garage.
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My problem is with the wording. I do not see the word "may" and "likely" being even close to meaning the same thing. To me "may" means that it is physically possible that the gas pipe would become energized. This would apply to any and all gas piping as it would be possible for the piping to become energized. The term "likely", to me, means that I have a reasonable expectation that the piping will become energized. In most installations, that is not a reasonable expectation.
Note, as I said in a previous post, CMP 5 says the two terms have exactly the same meaning. I just don't see it that way.
 
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