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CSST touching steel ductwork


John Dirks Jr
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I found this at an inspection yesterday. I'm posting so fellow inspectors can see what to look out for.

Lightning strikes can cause electrical surges in CSST. Arcing can happen where CSST is close or touching other potentially grounded systems such as steel duct work. The arcing can burn holes in the CSST and lead to gas leaks and fires.

If you see this, call it out and recommend that proper grounding of CSST piping is verified.

CSST should be kept away from other metal components to the extent possible.

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I found this at an inspection yesterday. I'm posting so fellow inspectors can see what to look out for.

Lightning strikes can cause electrical surges in CSST. Arcing can happen where CSST is close or touching other potentially grounded systems such as steel duct work. The arcing can burn holes in the CSST and lead to gas leaks and fires.

If you see this, call it out and recommend that proper grounding of CSST piping is verified.

CSST should be kept away from other metal components to the extent possible.

Please expand.

How far away should CSST be kept from other metal components?

What is your reference?

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I was alerted to this by a professional PE who spoke at one of my ASHI state chapter meetings a few months back. I dug up his card and sent him an email requesting information.

I searched the internet like anyone else can do and found lots of stuff about CSST, lightning and bonding. There is plenty of talk about lightning strikes with regard to bonding as well but I didn't find any specific things about installation close to metal ductwork and such.

It's early in the investigation process with CSST and failure due to surges from indirect lightning strikes. In my mind, it's easy to understand information shared by a professional may not yet be carved in stone.

With all this said Jim, you continue to impress me by challenging my thought process. I honestly appreciate it. If the PE responds to my inquiry, I'll share the information.

How far away should it be kept from other metal components? One inch away is better than laying right against them.

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I was alerted to this by a professional PE who spoke at one of my ASHI state chapter meetings a few months back. I dug up his card and sent him an email requesting information.

Ah! Is that in contrast to an amateur PE?

(Sorry, I couldn't resist the temptation to mock.)

I searched the internet like anyone else can do and found lots of stuff about CSST, lightning and bonding. There is plenty of talk about lightning strikes with regard to bonding as well but I didn't find any specific things about installation close to metal ductwork and such.

It's early in the investigation process with CSST and failure due to surges from indirect lightning strikes. In my mind, it's easy to understand information shared by a professional may not yet be carved in stone.

Perhaps, but surely we could expect it to be carved in something. Soap, even.

With all this said Jim, you continue to impress me by challenging my thought process. I honestly appreciate it. If the PE responds to my inquiry, I'll share the information.

In that case, I shall hold up my end of the bargain by continuing to challenge you.

How far away should it be kept from other metal components? One inch away is better than laying right against them.

If arcing is the issue, that might not be true. It might be better for them to actually touch. In fact, if the concern is voltage gradiants, it might be wiser to establish multiple bonding points rather than trying to establish separation that might be difficult to maintain.

I'm kind of doubtful about the whole idea, though. If the CSST and the metal objects are both properly bonded, how likely is it that a nearby lightning strike will produce much of a voltage gradient between them? It isn't like the earth, where you can develop huge potentials across very short distances. Metal objects are relatively good conductors of electricity.

- Jim Katen, Oregon

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I'm kind of doubtful about the whole idea, though. If the CSST and the metal objects are both properly bonded, how likely is it that a nearby lightning strike will produce much of a voltage gradient between them? It isn't like the earth, where you can develop huge potentials across very short distances. Metal objects are relatively good conductors of electricity.

- Jim Katen, Oregon

Basically, I agree with you, but it's an overly simplified picture of actual conditions. There are likely connections in that gas line of some type and neither the line nor the connections were designed or intended to conduct electric currents, much less atmospheric discharge currents. Also, bonding systems and the conductive components that may be connected to them are characterized as having nodes which are points where three or more conductors are joined. Conductors between nodes are themselves characterized by an impedance which responds in calculable ways when currents or charges pass through them.

I'd avoid trying to figure out what would happen under various scenarios given the complexities and just use the codes, perhaps google for a few minutes and apply a moderate amount of common sense to determine if there's an HI finding or not. That seems pretty much what John has done in his OP.

Just my opinion, is all.

Marc

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Some studies have suggested that the yellow jacket on the tubing holds back current. The current then builds up until it finds a weak spot where it can find a ground then, POP!!, it jumps and burns a hole in the tubing. This might be behind the suggestion to keep the tubing away from other potentially grounded systems.

There's a manufacturer making CSST that has a coating which is conductive. The idea is to allow energy to spread out across a larger area and reduce the chance of burning through the tubing.

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I'm kind of doubtful about the whole idea, though. If the CSST and the metal objects are both properly bonded, how likely is it that a nearby lightning strike will produce much of a voltage gradient between them? It isn't like the earth, where you can develop huge potentials across very short distances. Metal objects are relatively good conductors of electricity.

- Jim Katen, Oregon

Basically, I agree with you, but it's an overly simplified picture of actual conditions. There are likely connections in that gas line of some type and neither the line nor the connections were designed or intended to conduct electric currents, much less atmospheric discharge currents. Also, bonding systems and the conductive components that may be connected to them are characterized as having nodes which are points where three or more conductors are joined. Conductors between nodes are themselves characterized by an impedance which responds in calculable ways when currents or charges pass through them.

Well, sure. But if the two metal systems are bonded to each other, there's very little risk of arcing between them. Whether or not they were designed to conduct current, the very firm metal-to-metal connections still have conductivity that's hundreds of times greater than even a very small air gap. Unless we're talking about a direct lightning strike. . .

I'd avoid trying to figure out what would happen under various scenarios given the complexities and just use the codes, perhaps google for a few minutes and apply a moderate amount of common sense to determine if there's an HI finding or not. That seems pretty much what John has done in his OP.

It's the last sentence of his post. It has nothing whatsoever to do with the code requirements or with the manufacturer's installation requirements. And, so far, I've seen nothing from Google on the subject. So how, exactly, has John used the codes, google, and a moderate amount of common sense here? What I'm getting is heresay from a PE with unknown qualifications and who doesn't seem to provide references for his claim to keep CSST away from other metal components.

With no offense toward John, this kind of information is worse than useless.

- Jim Katen, Oregon

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Some studies have suggested that the yellow jacket on the tubing holds back current.

I don't understand. Do you mean that the yellow jacket is an insulator and it prevents current from flowing from the CSST to a nearby piece of metal (which, of course it does) or do you mean that it holds back current as a choke coil, slowing or preventing current from flowing on the CSST itself? If the latter, I'd love to see the reference for that.

The current then builds up until it finds a weak spot where it can find a ground then, POP!!, it jumps and burns a hole in the tubing. This might be behind the suggestion to keep the tubing away from other potentially grounded systems.

The current builds up? Do you mean the voltage? This explanation seems to favor the choke coil theory - that the plastic jacket is preventing or slowing the flow of current on the tubing. I am skeptical.

There's a manufacturer making CSST that has a coating which is conductive. The idea is to allow energy to spread out across a larger area and reduce the chance of burning through the tubing.

OK. Who?

Where are the references for this stuff?

And more to the point, does anyone have access to data about CSST failures that have occured on systems that were properly bonded?

I know that the early CSST failures all occured on systems that were not properly bonded. I'm interested in data from systems that were properly installed.

- Jim Katen, Oregon

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Robert Torbin is the gentleman who spoke at the ASHI chapter meeting.

I thought I recognized the name. I found it in the 2009 Edition NFPA Gas Code Handbook. Mr. Torbin authored a supplement in the handbook titled Update on the Design and Installation Requirements for CSST Gas Piping Systems. I don't see any mention of "CSST should be kept away from other metal components to the extent possible". I don't find it anywhere in the 2009 gas code or anywhere in my handbook.

Mr. Torbin's text does however, support what Mr. Katen has been explaining. "Electrical Bonding and Grounding, has been revised to require that all CSST systems be bonded to the electrical service ground where the gas service enters the building using at least a 6 AWG copper conductor or equivalent. This bond is intended to divert much of the lightning energy directly to earth before it can jump to another nearby electrically conductive pathway, such as copper water pipe or electrical wiring".

I'm thinking what was said verbally may have been misinterpreted. He may have been explaining what could/did happen when CSST, not properly bonded, was near other conductive materials.

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I don't see any mention of "CSST should be kept away from other metal components to the extent possible". I don't find it anywhere in the 2009 gas code or anywhere in my handbook.

This is from page 48 of the Gastite Design and Installation Guide November 2008-

Care should be taken when installing vertical runs to maintain as much separation as reasonably possible from other

electrically conductive systems in the building.

4.3.2 Horizontal Runs

Tubing routed on top of ceiling joists and other structural members which comply with the horizontal support spacing

requirements will be considered sufficiently supported . See Figures 4-24, 4-25, 4-26 and 4-27 for examples of acceptable

support configurations when routing Gastite®. Gastite may be routed beneath, through and alongside floor and ceiling

joists. Due consideration must be given to future construction possibilities. Horizontal runs in concealed areas must

conform to Section 4.4 Protection.

Care should be taken when installing horizontal runs to maintain as much separation as reasonably possible from

other electrically conductive systems in the building.

I added the bold.

Jim

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I don't see any mention of "CSST should be kept away from other metal components to the extent possible". I don't find it anywhere in the 2009 gas code or anywhere in my handbook.

This is from page 48 of the Gastite Design and Installation Guide November 2008-

Care should be taken when installing vertical runs to maintain as much separation as reasonably possible from other

electrically conductive systems in the building.

4.3.2 Horizontal Runs

Tubing routed on top of ceiling joists and other structural members which comply with the horizontal support spacing

requirements will be considered sufficiently supported . See Figures 4-24, 4-25, 4-26 and 4-27 for examples of acceptable

support configurations when routing Gastite®. Gastite may be routed beneath, through and alongside floor and ceiling

joists. Due consideration must be given to future construction possibilities. Horizontal runs in concealed areas must

conform to Section 4.4 Protection.

Care should be taken when installing horizontal runs to maintain as much separation as reasonably possible from

other electrically conductive systems in the building.

I added the bold.

Jim

Thank you. I finally found the same thing echoed in the other CSST manufacturer's instructions.

- Jim Katen, Oregon

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Im glad some language supporting my position was posted.

With that said, next time I'll do my best to find the references first and include them with the post.

I respect all the members on this forum and give high merit to the information I get here.

I have to admit, with Jim Katen challenging me, I was seriously doubting myself. Who wouldn't?

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Im glad some language supporting my position was posted.

With that said, next time I'll do my best to find the references first and include them with the post.

I respect all the members on this forum and give high merit to the information I get here.

I have to admit, with Jim Katen challenging me, I was seriously doubting myself. Who wouldn't?

I.

Marc

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Im glad some language supporting my position was posted.

With that said, next time I'll do my best to find the references first and include them with the post.

I respect all the members on this forum and give high merit to the information I get here.

I have to admit, with Jim Katen challenging me, I was seriously doubting myself. Who wouldn't?

I.

Marc

Smack down.

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A dissenting viewpoint:

Bonding of CSST is a solution in search of a problem.

Thanks John for posting those links. They are informative, though I do not think of them as authoritative. The NFPA annual report on lightning tells us that we have some 4800 house fires a year as a result of lightning. We have now 4 documented cases of CSST contributing to those lightning fires. Something doesn't make sense.

When the second CSST lightning fire occurred the class action suit was born. The settlement of same never did result in monetary awards - other than to pay the cost for installers to bond it in the manner that had already been required by code.

The purpose of bonding gas piping in the NEC is to create a fault return path and to eliminate voltage potential between metal surfaces. It has nothing to do with lightning.

The gas industry historically has had a prejudice against bonding of their piping, in part because of very real dangers that arise from static electricity while working on open pressurized underground gas lines. I don't mean any offense to them, but they have also repeatedly demonstrated an historical lack of understanding of electricity. I once heard the head of a major utility's gas division proudly announce that they were prohibiting the bonding of their gas piping - and would remove the meter from a house - if the piping were bonded in any such manner that current could flow on it. He seemed to think that bonding gas piping would put voltage on it. It does the opposite. It helps clear a fault to get it off the gas piping.

Current only flows on conductors in the presence of a difference of voltage. Voltage potential between any two metal surfaces is a hazard, all the more so when one of them is gas piping. Maintaining a separation between items such as gas pipe and metal ducts, only to later bond them together to the same grounding target at the service, is just plain silly, but it plays well to the gas industry.

The motivation behind the CSST industry's initial response (when they were requiring the 8AWG bonding at the manifold) was a way to say "we've done something - we've solved whatever problem we had." Likewise, the current IFGC, IRC, UMC, UPC, NFGC requirement for the 6AWG bonding conductor on the hard piping upstream from the CSST is the result of the industry convincing the authors of the gas codes to play along in this feel-good campaign.

The CSST industry was not successful in getting this into the NEC, and I doubt they ever will be. The folks on CMP-5 (those responsible for article 250) actually understand electricity, grounding, and bonding. They will allow bonding as the manufacturers requested, because it is doing no harm. They will not buy into the mistaken notion that this new particular method is somehow an improvement. Their language in rejecting the proposal was as follows:

Panel Statement: CMP-5 is not convinced that bonding to or around portions of CSST will solve the problem. No test records were provided to substantiate the adequacy of the minimum 6 AWG conductor. The problem could be directly related to the design and wall thickness of CSST. CMP 5 was made aware of at least one manufacturer’s product that does not require bonding beyond the requirements of Section 250.104 contrary to the information provided in the substantiation. The mitigation of the effects of lightning is a design option. The purpose of the NEC is the practical safeguarding of persons and property from hazards arising from the use of electricity. The recommendation is not currently prohibited by the NEC and should be covered by product standards. NFPA 54 contains bonding requirements specific to this product, and those requirements do not conflict with the NEC requirements in Section 250.104(B).

To me bonding of CSST is just another in a long line of useless rules that we are saddled with due to the politics and semantics of codes, without any basis in reality. I'm sure we can all think of others. Several examples come to mind. Start with bonding hydromassage tubs. The NEC made an awkward attempt to outlaw "dummy" grounding terminals on double-insulated pump motors (those without a grounding conductor) in the 1999 NEC. Because it was a last minute insertion by the CMP, and not a public proposal, their poor wording made its way into the code, and was revised in each of the subsequent four editions in an attempt to conform to some reality while also saving face. No one has ever been electrocuted in one of these things, and the bonding is redundant to the grounding and to the GFCI requirements. Yet how many times have I seen home inspection reports that make a big deal of this phantom defect?

Another one is AFCIs in bedrooms. No one ever made an NEC proposal to place them just in bedrooms. The floor debate back in the 1998 NFPA conference was for all or nothing. The idea of bedrooms came along at the last second as a compromise - a way to get the camel's nose under the edge of the tent. Yet how many home inspectors act as if these rooms were somehow more important than other areas of the house? It looks silly now that bedrooms are no longer the only area targeted for these devices.

The list goes on. Why 25 ohms resistance for the grounding electrode?

In earthquake country, flexible gas connectors are the norm, and they are nowhere near as robust as CSST. They have been around a lot longer also. Don't tell the lawyers.

Douglas Hansen

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It makes just as much sense to think that you reduce the chances of lightning damage by throwing salt over your left shoulder when the moon enters Aquarius.

Bill quoted the engineer at the source of this misinformation as having written: "Electrical Bonding and Grounding, has been revised to require that all CSST systems be bonded to the electrical service ground where the gas service enters the building using at least a 6 AWG copper conductor or equivalent. This bond is intended to divert much of the lightning energy directly to earth before it can jump to another nearby electrically conductive pathway, such as copper water pipe or electrical wiring".

There is so much to pick apart in that last sentence I hardly know where to begin. First, "lightning energy" rises from the earth as much as it goes down to it - it's an AC current that pulses. Second, the "water pipe or electrical wiring" are also supposed to be bonded. Elevated voltage through the structure from a lightning strike affects all conductive materials. The water piping and electrical wiring already have the "lightning energy" on them. The author wants us to believe that lightning is going to somehow reach earth through the CSST bond before (his word) that lightning reaches the earth through the even better path of the electrical wiring. Where do we get such men?

Lightning protection systems operate on the principle of creating an umbrella around a structure. The idea that somehow lightning is going to be controlled (or that damage from lightning can be predictably minimized) by taking it through ONE of the metal systems in the building and bonding it differently than the others, while separating it from the others, is pure hokum. That is why the electrical code treats bonding of these systems from the viewpoint of shock hazards and clearing faults, and NOT from the standpoint of lightning protection.

One of the original Texas CSST lightning fires happened from a lightning strike on a metal chimney. There was CSST to the fireplace connected to that chimney. The chimney acted quite predictably as the lightning rod for the building. If they wanted to protect the gas piping, the way to do it would be to ground the chimney. It worked for Franklin; it still works.

John, I think you have been victimized by the self-serving PR of the manufacturers and their interest in finding simple ways to reassure the public that their product is safe. It always was, but reality becomes irrelevant when the lawyers step in and file class action suits based on a statistically meaningless anomaly. If I was a CSST manufacturer, I don't think I could stand up and say the emporer has no clothes. It would be much easier to recommend a harmless bonding conductor.

Douglas Hansen

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Im glad some language supporting my position was posted.

With that said, next time I'll do my best to find the references first and include them with the post.

I respect all the members on this forum and give high merit to the information I get here.

I have to admit, with Jim Katen challenging me, I was seriously doubting myself. Who wouldn't?

I.

Marc

Thanks. Really. I'm here to learn just like everyone else. It's why I ask questions and press people when things don't make sense to me. It's how I learn.

While, I don't articulate my appreciation for your posts very often, I do find them interesting & challenging.

- Jim Katen, Oregon

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A dissenting viewpoint:

...just another in a long line of useless rules that we are saddled with due to the politics and semantics of codes, without any basis in reality. I'm sure we can all think of others. Several examples come to mind. Start with bonding hydromassage tubs. The NEC made an awkward attempt to outlaw "dummy" grounding terminals on double-insulated pump motors (those without a grounding conductor) in the 1999 NEC. Because it was a last minute insertion by the CMP, and not a public proposal, their poor wording made its way into the code, and was revised in each of the subsequent four editions in an attempt to conform to some reality while also saving face. No one has ever been electrocuted in one of these things, and the bonding is redundant to the grounding and to the GFCI requirements. Yet how many times have I seen home inspection reports that make a big deal of this phantom defect?

Another one is AFCIs in bedrooms. No one ever made an NEC proposal to place them just in bedrooms. The floor debate back in the 1998 NFPA conference was for all or nothing. The idea of bedrooms came along at the last second as a compromise - a way to get the camel's nose under the edge of the tent. Yet how many home inspectors act as if these rooms were somehow more important than other areas of the house? It looks silly now that bedrooms are no longer the only area targeted for these devices.

The list goes on. Why 25 ohms resistance for the grounding electrode?

In earthquake country, flexible gas connectors are the norm, and they are nowhere near as robust as CSST. They have been around a lot longer also. Don't tell the lawyers.

Douglas Hansen

The same kid in me that likes the story of David and Goliath really has me tempted to frame this and put it on the wall in my office.

During the years I've been doing this, I've observed a very slow and curious movement within our profession away from code, as general standards to promote safety, and into a camp where code becomes a bit of a self-edifying religion demanding that we chant it, as we all march in lock-step.

Don't get me wrong, I'm all for codes. In the 70's I walked through a home in WV that had particle board sub-floor on 24" centers with wicked sags between the joists fearing for my safety. I have simply never felt compelled to join the church of code.

You da man, David.. eh.. Douglas [:-thumbu]

All that being said, I have been an avid fan of Code Check since it first came out. It's a great little field reference for home inspectors. As a condensed and abridged version of the codes, complete with graphics to help visualize things, I couldn't imagine being without them.

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