Recently the area I work in (SF,CA) changed it's gas bonding rules. And wondering if anywhere else does it our new way?

Old way: Made Electrode/Rod and Water to Main Panel or Meter/Main combo. Bond hot, cold and gas at water heater.

New way: Made Electrode/Rod and Water to Main Panel or Meter/Main combo. Gas next nipple past gas meter to Main Panel or Meter/Main combo, or to any electrode, but not between electrodes. Bond hot and cold at water heater.

Anywhere else doing this?

I am sorry, maybe I am a bit dense this morning but I didn't understand you "new way" so let me address the bonding of the gas piping.

The gas piping is not required to be bonded unless it is expected that it may become energized. In that case, the circuit that may energize the pipe is where the bonding conductor is to be taken from. The bonding of the gas appliance is considered to be sufficient for the bonding of the gas pipe that feeds that appliance without any additional bonding.

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Charlie Eldridge, Indianapolis, Utility Power Guy

250-104(B) also says you can bond the gas piping to the service equipment, the grounded conductor at the service,the GEC, as well as the EGC of the circuit likely to energize. my question is how would you determine which circuit may rub through or accidentally come in contact with the gas pipes? wouldn't a CYA move be to just bond the the service?

Why bond what is not likely to be energized?

I was just in a basement last week that had an old piece of BX close to touching the gas pipes, the BX wasn't grounded, and somewhere in its length the hot had come in contact with the armor. WELL, let me tell ya, touched the armor and the sparks flew! The cable touched the pipe, grounded out, opened the OCPD. Point is, this installation was put in a LONG time ago, and at the time, there might not have been any reason to think there was going to be a short against the gas pipes. How do you determine if it will never be energized?

Here it is inspectable during every service alteration. Fail, for non-compliance of it. Always has been in my area of California, at least. The way it has been read, is that it is always been "likely to become energized".

It nice to know that iterpretation is a little different everywhere you go.

double post


[This message has been edited by e57 (edited 09-11-2004).]

How we determine it here is simple, if it is not connected to an electric appliance it is not likely to be energized.

It could be be energized but it is not likely.

Each area has their own way and here we do not bond gas pipes except by the EGC of equipment connected to it.

If the service neutral opens do you really want the gas piping at an elevated voltage, subjecting gas workers to a shock?

Another question:

Why do you suppose the NEC even put the words "may become energized" in this section if they meant all metal piping systems must always be bonded?

To each their own.

Bob



[This message has been edited by iwire (edited 09-11-2004).]

Personally, I find it a real pain in the end. As now we have to find a path to the otherside of a building to do it sometimes. But would fail inspections for it otherwise. (Although California, and SF, ignore this part: "The equipment grounding conductor for the circuit that may energize the piping shall be permitted to serve as the bonding means.")

In California we are using the 2001 CEC which is based on the 1999 NEC. 250-104(b) says that the interior metal gas piping must be bonded to the grounding electrode system. It doesn’t say anything about likely to become energized.

For many years every jurisdiction I have worked in except San Jose has required a bonding jumper between the hot, cold and gas pipes at the water heater. If you tell the inspector that the NEC permits the EGC of the appliances likely to energize the piping to serve as the bonding jumper he or she will tell you they still want the jumper at the heater. I have spent too much time arguing with inspectors over this issue and have decided to install the jumper for them. Now that we are on the 99 NEC I don’t have much of an argument but since I haven’t run across any inspectors that will not permit this jumper to be at the water heater I keep my mouth shut. Mark has finally run across some inspectors that realized what the 99 NEC requires.

Curt

Yeah, Curt didn't think there was too much of a change to 2002, from '99 on this, but it is pretty significant is it not?

Has a footnote for a referance, wonder if that changed?
Ref: A-250-104(b)
National Fuel Gas Code, NFPA 54-1996

Took a few years to enforce it! As it seems to relax in 2002, I wonder what happens for 2005? Not that California will adopt it until 2007, if at all.

Only slight wording changes in '93, but same referance. Anyone have a copy of the National Fuel Gas Code, NFPA 54?

That was never the intention of NFPA 54 and is reflected in a formal interpretation of that section, that is why the NEC was changed back to the 1996 language.

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Charlie Eldridge, Indianapolis, Utility Power Guy

Quote: If the service nuetral opens, do you really want the gas piping to be at an elevated voltage, subjecting the gas workers to a shock?"

how would this be any diffrent for the plumbers working on the water main when the nutral was opened?

How would any elevated potential develop on grounded pipes? wouldn't the OCPD clear any faults? I would think an ungrounded gas pipe would be more dangerous to the gas man, if a hot wire gets laid on the piping, what would clear the fualt, assuming that the gas pipe is servicing a non-electrical appliance?

[This message has been edited by trekkie76 (edited 09-13-2004).]

You are correct and I wish we did not subject the water workers to this either.

There have been threads on the forums about water company's that do not allow the water pipe to be used a grounding electrode, they install a dielectric fitting before the meter and do not allow it to be jumped.

Then of course when a water pipe is separated the product that leaks out is not flammable. If there was current in the gas line when they break a union the resulting spark may not be welcome.


If the service neutral opens all grounded objects will be have an elevated potential to earth. This is particularly true if you have a plastic water main, as you will not be connected back to the source through your neighbor. This has nothing to do with the OCP.



Here IMO is where it gets cloudy, which is more likely? A bare hot wire contacting and remaining against a gas pipe or a service neutral opening.

It has been my experience that the service neutral opening is more common but my experience means nothing I would really be interested in facts and figures.

I also would ask again why the NEC used the words "may become energized" if they did not want some choice in the matter.

It would be simple for the NEC to state

"Gas Pipes Shall be bonded"

But they did not.

Anyone else have some input?

Bob

if the service nuetral opened with a properly installed EGC( made electrode or water pipe), what would happen if the nuetral opened? nothing, in theory. IMO the purpose of comprhensive grounding is to limit any possibility of potential forming between any mettalic pathways. I guess there are many scenerios that could be played out in this one. But isn't our job to anticipate the "what -if's" of life?

After fifeteen years of doing this, I have only counted the years, (So no stat's) but would say neutral drop out is more common than the one or two shorts I have seen clear on a gas line. However I have seen MANY shorts clear on water lines, as there are many more of them in any building. I guess it is that the gas be able to trip OCP, or MOCP rather than have it remain live, or worse cook off using the gas as an electrode. (However, the new high pressure lines here have a ground wire that PG&E bonds past the shut-off????)

My main gripe with it, is that it changed in '99 to "upstream from the shut off". (reflecting the same commentary in '93!) (We're on the '99, and probably will be until 2007, when we may or may not adopt 2005!)Making it simular to the change in '93 that moved the water to 5' from the entrance to the building. Making both a real pain... So in the '02 NEC it changes back. Why? Both '93 and '99 refferance National Fuel Gas Code, NFPA 54, (But doesn't in '02?)what is it that they are looking for, as it seems to me, that we are doing it for thier (the plumbers, etc.) benifit? Or ours, to clear OCP?

How do you figure this?

The only way that 'close to nothing' would happen is if the entire neighborhood has a common metal water system.

Many water mains are now plastic, the earth is not enough of a conductor to prevent the neutral from having a potential higher than the earth with a loose or open connection.

Open neutral, go to turn on the outside water bib to wash the car and you will be a conductor.


I agree but sometimes we need to know the most likely 'what if' that is why I said some facts and figures would be nice. We should not just do things based on are own experiences.

None this means anything if as you have to do what the AHJ expects in your area.

CharlieE has pointed out this.


I believe he is correct.

Bob

with a solidly grounded metal water pipe or made electrode system, wouldn't the effects of the service nuetral opening be minimized? the returns are all still grounded.

I assure you that an open service neutral is always a big problem for someone. It may be the premises that is being served or one of the adjacent properties but it will cause problems, it is the nature of the beast.

At the very least, the water piping system is not designed to carry the neutral current. After looking at the 800-ampere GEC for one service, the metallic water piping to the service on the next property that has a 100-ampere service and its GEC. I wonder about the voltage drop and ampacity of the circuit.

Now I'm going to throw out an analogy here, and don't go ape on me if your opinion might be different.

We bond to keep the potentials the same. Which makes sense to bond a gas,(although I have gripes about how I am being made to do it lately.) seeing that we bond water, and hot water. (If metalic) We bond the neutral to ground, because we want to keep the potential low there too. (Relitive to earth) And, so we don't end up with a floating neutral causing over-voltage in every multi-wire circuit. And we ground because we want to (essentially bond) the exposed equipment surfaces and other bonded items also at the same potential as the earth. We want to keep everything the same and low, voltage potential wise, Right?

So if all of this is true, and EVERY faucet and stove out there is metal, why do we not bond everything andban plastic piping sytems?

I do not think that there is anyway to connect the neutral to earth in a way that can limit the difference of potential by very much for 120 volt faults.

Take a ground rod and bang it into the earth, now connect a conductor to it from a 15 amp 120 volt source.

Will it trip the breaker?

If you where barefoot would you touch this ground rod?

As I understand it we connect the neutral to earth for two reasons. Lightning and a power company fault that sends high voltage toward your home.

How about this, we have the plumbers always use plastic water and gas lines. For a grounding electrode we drive rods or use Ufers.

Bob

Hey Bob,
I,m having fun, so bear with me while we play, "Pick apart the other guy!" A Code Forum favorite Game Show.... Kidding!

Now is there a load between the source and the rod? The breaker just might trip with no load. Would I touch it, with load I might, wouldn't let a child do it... No load, no! It might be a 500F degrees, or 120+/- volts, or somewhere in between. (Depending on soil conditions between the rod and the rod at the transformer.)

Survey says.... Bzzzzt!

Bob, just having fun. But, I have seen a short clear on a water not bonded to a service, and several concrete floors, not bonded to the service. Because there was a rod somewhere near the trannie feeding the whole mess. Most times the resistance is too high to do it, sometimes it isn't. So, yeah I think we ground for the two reasons you mentioned , and the one I did. (Potential differance to earth)

Now the plastic thing... I still have to drive two 8'x5/8" rods or a ufer anyway! I have to do a ufer for any foundation work over 20' continous! Even after driving two rods, if the foundation work is later. But not the other way, if I have a ufer, don't need rods. Welcome to my world.

Ok, where does "ufer" come from? It is a term I have used for years and have put many in, and have no idea.... CEE = Ufer?

And while I'm at it. IMO what is "IMO"?

IMO In My Opinion

Ufer as in George Ufer a guy who designed that system during WWII for buildings in the desert

Mark, this link should answer your question: http://www.scott-inc.com/html/ufer.htm

Thank you gents, I have learned something today!

LOL

I can kick things around and disagree without getting upset.

Very unlikely a ground will open a 15 amp breaker from a 120 volt source unless there is already a good load on it.

The combined resistance resistance of the rod at the service and whatever electrodes are connected to the power company source would have to be less than 8 ohms. If you got down to 6 ohms it would take some time to trip, to get a 'fast' trip IMO you will need to get down to 2 or 3 ohms.

IMO you would need some unusual conditions to have less than 8 ohms total.

Bob

In Calif.-So. Calif. Gas Co. territory: "The Gas Company" says NO don't bond to our stuff, even within the building. As of about three years ago, that statement changed because "The Gas Company" said, we are now using a dielectric fitting on new installations; you may bond the building gas piping. So, we bond.
Usually it's at the water heater: one Bonding Jumper from the ground bar to Gas , CW, HW in one convenient and accessible location.
Oh yeah, Any new foundations in conjunction with a new or upgrade service, even in an addition, then we get a UFER.