No more grounding gas pipe at HW heater?

[sfav8r]

This is a new one on me.

Just had an Inspector inform me that bonding hot/cold/gas at hot water heater is no longer acceptable. The gas pipe must be grounded within 5' of the entry point, just like the water pipe.

He acknowledged that it wasn't an NEC thing, but said in California they were adopting this due to concerns from the poco that a ground fault could energize gas lines. Grounding the pipe as it exits the building reduces the chance of this happening.

I asked a friend of mine who does a lot of new construction, and sure thing, they ground the gas at the point of entry.

Has anyone else run across this? It actually makes sense, I have just never heard of this requirement.

Thanks

[ July 07, 2005, 09:50 PM: Message edited by: sfav8r ]

 

[GG]

Re: No more grounding gas pipe at HW heater?

Well If you have an air handler with gas heat then the equipment grounding conductor that is run with the circuit that supplies power to the air handler has in affect just bonded the gas pipe to the system neutral at the service panel. Same with the circuit that feeds a gas dryer or a gas cooktop so I don't see what this inspector thinks is being accomplished by bonding the gas pipe within 5' of where it enters the building.

 

[jwelectric]

Re: No more grounding gas pipe at HW heater?

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

edited to add:

The gas pipe must be grounded within 5' of the entry point, just like the water pipe.

I would think that using the first five foot would in essence be making it part of the grounding electrode system




[ July 07, 2005, 11:36 PM: Message edited by: jwelectric ]

 

[sfav8r]

Re: No more grounding gas pipe at HW heater?

Originally posted by jwelectric:
I would think that using the first five foot would in essence be making it part of the grounding electrode system
[/QB]

The gas pipe has to be bonded separately. For example. If you are installing 2 ground rods, The first GEC goes from rod 1 to the panel, the 2nd GEC goes from rod 2 to the panel or the 2nd rod, and a THIRD GEC goes from either of the rods to the gas pipe...grounding it, but not making it part of the "system."

Electrically, this seems identical to me. However, if you go from rod 2 to the gas pipe, to rod 1, they will not pass. The theory (I think) is that at a high fault current you could end up with a potential on the gas pipe if the current is traveling a long distance.

It sounds to me (and I confess I really don't know) that there is waaaaaay more theory involved here than anything that could actually happen in the real world.

 

[tx2step]

Re: No more grounding gas pipe at HW heater?

Originally posted by sfav8r:
...and a THIRD GEC goes from either of the rods to the gas pipe...grounding it, but not making it part of the "system."

...if you go from rod 2 to the gas pipe, to rod 1, they will not pass. The theory (I think) is that at a high fault current you could end up with a potential on the gas pipe if the current is traveling a long distance.

By a long distance, do they mean maybe 10 or 20 feet, since that is what it will probably be? (Assuming that the gas pipe is in the general vicinity of the ground rods and not 100' away)

I think that the City needs a refresher on Ohms Law. Like it or not, they are making the gas pipe a part of the Grounding Electrode System.

I agree with you, electrically I see no practical difference in the two methods.

In the event of fault (or lightning) current flowing to the grounding electrodes, the underground gas pipe will take part of the current -- up to the point where the metallic piping eventually reaches plastic pipe or an insulating coupling.

If there is much electrically continuous metallic gas piping in the ground, then it is probably a far better grounding electrode than the 2 ground rods -- so it will take a large share of the current.

[ July 08, 2005, 02:33 AM: Message edited by: tx2step ]

 

[infinity]

Re: No more grounding gas pipe at HW heater?

I agree with JW. The gas piping system is required to be grounded if it is likely to become energized. This is accomplished by the connecting of the equipment grounding conductor run to a gas appliance. No further bonding is needed. In fact 250.52(B)(1) would prohibit this connection within 5' altogether since the underground gas pipe would now be a grounding electrode.

 

[goldstar]

Re: No more grounding gas pipe at HW heater?

This was a requirement here in NJ several years ago until someone in code enforcement at the State level realized that it was ridiculous. We would bond the gas line and when the gas utility came in to read the meter they would remove it. I believe "infinity" had the best answer here.

Mike Holt published a newsletter several years ago regarding a municipal gas piping system that was corroding throughout the town (I believe it was San Antonio, TX) where it was discovered that it was due to a long term practice of bonding gas lines in residences to the electrical grounding systems. If I can find the newsletter I'll post it here.

BTW - just because a State code requires this doesn't mean it's the right thing to do. Granted, you'll have to comply with the requirements but it's still ridiculous.

[ July 08, 2005, 07:34 AM: Message edited by: goldstar ]

 

[apauling]

Re: No more grounding gas pipe at HW heater?

I think most of it comes from the code changes in the last few cycles allowing a cord and plug to be the only bonding for gas lines.

This is one of those issues that can generate a lot of debate. If electricity was the cause of the failing gas lines, buildings all over the place should start toppling pretty soon as they were also part of the bonding system, and for much longer. I guess panels and water lines and whatever else was bonded, and ooh that ufer ground in the reinforcing steel, it's gonna fail pretty soon now if all that finger pointing is right.

I think IF a gas line is to be bonded, it should be where it enters the building, not where a device is plugged in. The likelyhood of a shock, or with CSST an actual arcing failure is more probable with current code. If there is an electrical fault where it is bonded at the outlet, with not enough current to trip the breaker, there exists the real possibility of an arcing failure as the gas line enters the building near other metallic paths back to the panel. This is not so likely with steel pipe, BUT with CSST that is another question.

Another point is the definition of "bonding" as a permanent connection, using parts listed for the purpose of bonding.

I just dislike the idea that the CSST industry got the requirement changed as there was no way to actually bond the CSST as it was too maleable. Wasn't a problem with steel pipe.

paul

 

[augie47]

Re: No more grounding gas pipe at HW heater?

Am I missing something here? There seesm to be a lot of discussion about the effect of the "bonding" and the underground gas piping.
The two don't mix..........

    [250.52 Grounding Electrodes
 (B) Electrodes Not Permitted for Grounding The following shall not be used as grounding electrodes: 
 (1)	Metal underground gas piping system  ]
 
 250.104 Bonding of Piping Systems and Exposed Structural Steel
 (B) Other Metal Piping Where installed in or attached to a building or structure, 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 to the one or more grounding electrodes used.[/QOUTE]
 
 
 In our area, we BOND, the interior gas piping (usually at the water heater) to prevent it form bcoming energized from a fault in a brnach circuit.(Thus complying with 250-104)
 
 The gas meters have isolation fittings that prevent this bond from being electrically continuous to the metallic underground gas piping (even though thats a a rarity now)(complying to 250-52 (B)(1)
 
 The "water heater" locations was selected simply as a readily identifiable point where it is easy to bond hot/cold/ and gas

 

[don_resqcapt19]

Re: No more grounding gas pipe at HW heater?

One, a GEC is never permitted to be connected to a gas line. A bonding conductor is connected to the gas line. A gas line is bonded, not grounded.
Two, the bonding of interior gas lines that are likely to be energized is required by both the NEC and the Fuel Gas Code. In both cases the EGC that serves the circuit that is likely to energize the gas line is permitted to provide the required gas line bonding.
Three, most gas utilities that are using metal undergroud gas piping use a dielectric fitting at the meter to prevent current flow from the building electrical system on the metal underground gas pipe.
Don

 

[petersonra]

Re: No more grounding gas pipe at HW heater?

I fail to see how semantics changes reality here.

There is a green wire going between the metal gas pipe and the ground rod (we'll say it is a rod for now) to bond it in some way (maybe not a direct path, but a path none the less).

How is this electrically any different than extending the GEC from the rod to the gas pipe?

 

[stud696981]

Re: No more grounding gas pipe at HW heater?

Whether you bond the gas pipe on the first foot or a 100 feet away, as long as its all metallic it is technically BONDED. The gas pipe can't be used as a grounding electrode method, but where you place bonding wire/jumper has NOTHING to do with it being viewed as a grounding electrode.

 

[peter d]

Re: No more grounding gas pipe at HW heater?

Originally posted by don_resqcapt19:
Three, most gas utilities that are using metal undergroud gas piping use a dielectric fitting at the meter to prevent current flow from the building electrical system on the metal underground gas pipe.
Don

Much like many municipal water systems, all of the new gas main and service installations are done in plastic in my area, and replacements are done in plastic as well. This applies to residential service though, I am sure the larger commercial mains are still metal.

 

[sandsnow]

Re: No more grounding gas pipe at HW heater?

Originally posted by sfav8r:
This is a new one on me.

He acknowledged that it wasn't an NEC thing, but said in California they were adopting this due to concerns from the poco that a ground fault could energize gas lines.

I have not heard this.
It is not in the 2004 Calif Elect. Code.
Can you ask your freind where he got this? A written refrence would be great.
Thanks.

 

[physis]

Re: No more grounding gas pipe at HW heater?

I think it's San Francisco.

Edit:

but said in California they were adopting this

Or did he mean he was adopting it?

[ July 08, 2005, 02:01 PM: Message edited by: physis ]

 

[electricmanscott]

Re: No more grounding gas pipe at HW heater?

Adopt this, Crazyfornia

 

[physis]

Re: No more grounding gas pipe at HW heater?

All this EMT has to come out and be replaced with RMC. Staps every 6 inches and connectors welded. You have to have two grounding conductors in the pipe in case one fails. And it's gonna cost $85 bucks cause this isn't ready for inspection.

[ July 08, 2005, 03:00 PM: Message edited by: physis ]