Flexible Gas Lines- Are You Serious?

41 responses

  1. M. Chadsey
    June 26, 2012

    Lightning strikes have caused some revisions to be made to the installation instructions for CSST. Arcing between the CSST and electrical lines was found to be the cause of these fires.

    The gas line is now required to be grounded and BONDED to the electrical system. This is usually accomplished by connecting the CSST gas line to the main ground rod with ground clamps and #6 solid copper wire.

    The 2009 editions of the International Fuel Gas Code and the Uniform Plumbing Code state in Section 7.13.2: "CSST gas piping systems shall be bonded to the electrical service grounding electrode system at the point where the gas service enters the building. The bonding jumper shall not be smaller than 6 AWG copper wire or equivalent."

    When the CSST piping is installed properly there is no more danger from lightning strikes that with any other gas system. Most manufacturers supply instructions on how to properly install ground clamps.

    I just installed a furnace in my attic with CSST piping. It was a little more expensive materials wise but saved me a lot of headaches with the complex bends and turns that were required to connect the gas line. It took me approximately 2 hours to run a CSST gas line that would have probably taken a full day of cutting and threading cast iron pipe.

  2. Robert M
    November 30, 2012

    If there is a problem with lightening strikes why don't they put a insulating type pipe at certain points to prevent the csst from being grounded making it safe from strikes. Or use pure plastic lines that are tough enough for the job. I can't believe in this modern time we only have three choices for gas lines.

  3. Patrick
    December 16, 2012


    I read your article and agree. I also read the email from the fireman. Rest assured, as an electrician we are already being told of the situation and in New York State, we are now required to bond the gas lines to the main electrical grounding electrode, in order to make sure such problems don't happen or are extensively minimized.

  4. Garry
    January 30, 2013

    What is meant by "bonded gas line"?
    We hired a contractor to convert an attic mounted heat pump to gas. They ran CSST from the basement to the attic alongside the refrigerant lines. Very neat install. They did attach a solid copper ground wire between the gas meter and main electrical ground using wire clamps, but how can I tell if it is "bonded"?

    • Tim Carter
      February 24, 2013

      Better have a pro electrician look at this for you.

    • Chris
      May 29, 2014

      "Bonded" simply means that there is a physical wire/electical coupling between the conductive materials (Only the grounded materials of course). The goal here is that the CSST and the elecrical circuit share the same path/circuit to potential earth, or ground. A meter or a visual check gould help you, but remember, residential 120V is the most deadly. If you don't know electrical, do what Tim says and call a pro.

  5. Cathy
    March 1, 2014

    Is there a metal gasket inside the end of the flexible pipe to keep the pipe from twisting? I unscrewed the pipe and it looks like half of one fell out. Can I just replace the end with another end piece with the gasket in it?

    • Tim Carter
      March 2, 2014

      Most of these flexible lines are simple flare fittings..... Read about that at my website.

  6. PCL
    March 13, 2014

    I've heard of the lightning issue and assumed there was a way to protect against it. It sounds as if that assumption was right; knock on wood. But my objection to any flexible gas lines in the walls of a house concerns what happens when someone tries to put up a big picture, shelving, framing for new partition, just about anything that would require screws or nails into the wall. Most people do this without a thought of hitting anything sensitive, and I'm aware that they hit water pipes and even cables from time to time, but the risk from hitting a gas line seems much higher. Are there any places where such lines require steel conduits when run in closed up dead space? Seems like a small price to pay for peace of mind.

    PS: Robert M. has an interesting point. I know plastic tubing (HDPE, PEX-AL-PEX, etc.) has been used underground for years. But I wonder if pure plastic would eliminate the risk for lightening strikes; there is, I believe, some water accumulation in these systems, and a resistive path could be even more dangerous than a direct short. I can imagine a pipe heating up and bursting if the right current makes its way through the moisture, thought I can't say for sure how plausible that would be. Similar questions must come up when water lines that had been used for grounding are spliced with plastic.

  7. Eddie Hatcher
    September 1, 2014

    Isn't all natural gas line buried and most come out of the ground in
    the black pipe, question is do I still to ground the flexible line?

    • Tim Carter
      September 2, 2014

      Yes, most natural gas lines are buried. You need to install the pipe according to all LOCAL regulations. Contact your gas supplier for instructions. DON'T GUESS or LISTEN to advice from others online. Don't HOPE you're doing it right. Contact the gas supplier.

      • Rick
        December 1, 2014

        Underground metal pipe as installed by the gas company is coated and cathodically protected (CP), meaning that a negative voltage is imposed on the material to prevent corrosion using anodes or rectifiers. As long as the pipe is more negative than the surrounding soil, the metal will not rust. In order to maintain this negative potential, the pipe is coated (as best as possible) to isolate it from the soil and has an insulator installed at the meter to prevent a home's AC grounding electrode system from bleeding the CP voltage off. LDCs (local gas distribution companies) frown on the practice of grounding their CP protected pipe.

    • Richard Frankfurter
      January 8, 2015

      Polyvinyl is approved for underground lines now so no it doesn't have to be black pipe.

  8. David Thompson
    September 18, 2014

    Could you use a grounding rod near the entrance of the gas pipes into the house instead of running a wire all the way back to an electrical panel that is in the opposite end of the house. It would be grounded by ground rod correct?

    • Tim Carter
      September 18, 2014

      What does the electrical inspector and gas company inspector say to do? Did you ask them?

  9. scott
    October 4, 2014

    You must run the ground wire back to the panel. If you drive another ground rod there will be a difference in potential. The bond must go back to the GES grounding electrode system.

  10. Darlene Cook
    October 14, 2014

    Is the flexible SS tubing okay for LP gas too?

    • Tim Carter
      October 15, 2014

      I have it in my home. Code-approved in New Hampshire. I can't say where you live

  11. Richard
    October 16, 2014

    When I attach my #6 ground wire to my flex gas line fitting, can I just attach the running length of the ground wire to the side of my brick on the house as it makes its way to the panel box on the inside of my home. Thanks

    • Tim Carter
      October 17, 2014

      What does your local electrical inspector say about this?

  12. mike Rizzo
    October 17, 2014

    I am considering using the yellow flex line to run from the basement up through the old fireplace ash shute to connect to a set of vent free fireplace logs in an existing fireplace. Is this something that would be safe?

    I am also looking for step by step instructions from someone who may have done this type of install before.

    • Tim Carter
      October 17, 2014

      What does your local building inspector have to say about this?

  13. Taylor
    November 14, 2014

    I am in the process of changing out my CSST. First of all after it was installed everyone in the house would hear a high pitched ring when the furnace and stove ran at the same time. If you have high pressure gas ringing through the lines at too quick of a rate the lines can hum or ring. In our case we had xcel come out and they said they see it all of the time. Manufactuer acknologed this issue. As far as the safety issues they are very real even if you bond it correctly the issue is really the thickness or in its case thinness of its walls. Soft copper has none of these issues and is fairly easy to work with. I would stay away if you can.

  14. Paul
    December 23, 2014

    does each length of the csst have to be grounded, since there are rubber gaskets in the fittings?

    • Tim Carter
      December 24, 2014

      No. Think about it. What is TOUCHING where the CSST connects to other metal piping?

  15. Dorman Davis
    January 16, 2015

    I install gas lines for a living. I am also a firefighter. This gas line, the yellow stuff is great if properly installed. There is a new type hitting the market. It's coated with rubber to resist lighting issues. You can cut down on the whistling noise simply by going to the shut off up stream and turning it down till the noise stops. Your slowing the speed of the gas going thru the pipe. That's the issue. It cannot be installed in fireplaces.

  16. Dave
    March 1, 2015

    This article and it's associated comments were fantastic, helpful and informative for a new homeowner like me.

    I'm having my 26 year old Trianco Heatmaker boiler replaced soon with a Bosch Greensaver 100 Combi propane boiler in my basement. The install will be done by a large, local energy company here in Maine.

    When the energy company representative came over he measured out rooms, checked our forced hot water baseboard in each room, checked our boiler and took pictures of it. During this process, he mentioned that our CSST line needed to be grounded, and that getting my own electrician would be cheaper than what his would charge.

    I'm wondering what this work would typically cost. My CSST line runs through the basement ceiling near the circuit breaker, and my rudimentary understanding is that it would require a clamp and copper wire to the main ground.

    I'm wondering what the typical local electrician might charge for this, as the energy company representative seemed to imply that it's expensive.

    Thanks in advance for any possible help.

    • Dave
      March 2, 2015

      Just a quick update. I'm told that I need to have #6 copper wire run from the grounding bar at the main circuit to the pipe where the gas first comes in outside, secured with a clamp and some scrubbed section of pipe.

      I'm told the wire can be stapled to joists along the basement ceiling to the circuit breaker box.

      My question was whether this would be a huge expenditure or not, and I'm now being told by the energy rep that it won't be a massive expenditure.


  17. Bruce
    July 26, 2015

    I have been reading all the informative emails from other professional gas line installers and fireman and trying to understand the grounding/bonded issue for using CSST....My question deals in that I already have the black iron pipe 3/4" thick for my gas line coming into my house which has been installed throughout my house which was built in 1987 and I wanted to reroute the existing gas line from it's current location in one wall on the main level (flipping my kitchen into my dining room) and it would be better suited to reroute the gas line using the flexible CSST to snake around already installed vents and air ducts running into my basement and instead of using the more rigid black pipe which might be hard to install around those confined spaces.
    So my question is would I still need to ground/bond the flexible CSST if I am hooking it up to the existing Black Gas line in my home?

    • John
      September 17, 2015

      Yes as far as I know you would need to ground/bond any CSST in your home. The black iron does not insulate CSST that may be connected to it

  18. JR Murphy
    October 20, 2015

    I have read all of the emails and questions concerning CSST and it's use. I like the response of "What does your local Electrical Inspector say?" & "What does your local Building Inspector say?" I have been working with these "Inspectors" for years ands can tell you that they can read the code book but interpreting it and putting the code to practical use in the field are two totally separate things altogether. First, yes the installation of CSST takes less labor time. That is where the advantages end for me and for anyone with some knowledge about building practices and common sense. The Black Iron pipe is "sized" for the amount of gas appliances intended to be installed and used in the home. This MUST be done by a professional that knows how to use the gas sizing charts in the code book. The same is required to be done for the use of CSST. This practice is commonly overlooked and also many times undersized gas piping is not caught by "inspectors". Black Iron Pipe is cut and threaded and does take a lot of time, knowledge and expertise to install correctly, (it is Gas, how do you want it contained in your home?) the system is then pressure-tested with air at pressures above what it will endure when the gas is finally introduced. If there are any leaks in the system, they must be corrected at that time. Same as CSST. Tim's statements make it seem as though leaks occur from time to time and it is easier to fix them and the potential is greater when using Black Iron Pipe, nothing could be further from the truth.


    Please go back and re-read what I said. My comparison is that with CSST you only have a leak potential at each end of the run where you have a fitting. With black iron - and I've installed THOUSANDS of feet of it - you have a leak potential at each side of each fitting as you install the pipe throughout a house. In one run, you may have ten or more 90's, couplings, tees, etc.!


    There is always a potential for a leak in ANY system utilized. When installed by a Licensed and Insured Professional Plumber the chances are minimized and then eliminated when a proper inspection/pressure test is done. If one adds up the amount of hours spent worrying and contemplating the grounding and bonding issues associated with the use and installation of CSST, how much labor did you really save? This CSST and other like materials to save on labor was embraced by builders who wanted to save money on labor. One question, did the price of the house go down? Answer: NO
    The labor savings went into the builders pocket. Like many of the other products introduced into the marketplace as being "just as good" or "think of the money saved on labor" Why do we want to eliminate the professionals from the marketplace? When there is a problem the builder or consumer can't solve, they call a professional to solve it and usually complain about the price, why? They saved all this money on putting in cheaper, less labor-intensive materials and now want to scream when it ends up costing them the same and they don't have near the quality of product in the end.The attitude of "It's somebody else's problem when I sell the house" is ludicrous. If everybody has that outlook/attitude, who are you buying your next house from and what attitude do they have?! Soft copper simply should not be used on Natural Gas, the odorant that they put in the gas has been shown to "eat away" at the copper over time, you don't see this because the gas is on the inside of the pipe doing the damage. A professional sees this when they take apart the pipe or are working on gas appliances a few years labor and notice all of the black flakes in the gas system. Do your research, better yet, hire a licensed professional. Stop trying to "save a Buck" on something that could kill you in the end.

  19. Kathy
    December 19, 2015

    My home is 12 years old. The natural gas line (CCST exactly like pictured in your post) had a cut in it right where it entered my home from outside. The repair man said the break was right where the line rubbed on the edge of the heating duct work and he surmised that the duct work edge cut into the pipe.

    However, what I didn't tell him was that my husband had just moved out of our home the night I began smelling the gas (repair man came the next morning) and it was under difficult circumstances. I had to get a court order to force him out due to abuse.

    The portion of damaged pipe was thrown out and I know I'll never get a definitive answer, but the original repairman is insisting the duct work did the damage, however, his colleague told me that the inside steel lining would never be able to be "cut" by duct work and that the circumstances are highly suspicious.

    What are your thoughts?

    • Tim Carter
      December 22, 2015


      Without having a photo to look at I can only take a guess. My instincts tell me that the rounded corners of standard ductwork will not cut through the wall of CSST pipe.

      Years and years of rubbing may cause an issue, but there'd have to be a reason why there was movement causing this friction.

      That damaged piece of pipe should have NEVER been discarded. Don't let that happen again. SEND me a photo via the Ask Tim link above of the situation. I wish you the best and will include you in my prayers.

  20. George
    January 28, 2016

    I have about 95 feet of black steel pipe in my home and 5 feet of CSST to the fireplace. ...... a leak at the flare coupling of the CSST will now cost me hundreds of dollars to fix ... would not it have been smarter to have the final 5 feet done in black steel pipe at the time the home was built 12 years ago.

  21. Dave D.
    March 24, 2016

    I just had 32' of black CSST spliced into my iron gas pipes and run under my 14x60 mobile home in a straight shot, parallel to the structure, from the regulator to the new valve. It's for a new gas log stove, yet to be installed. The existing gas lines are all black iron pipe. The existing lines, if installed correctly, should already be grounded to the electrical panel, right? If it is (and I will check to be sure), then this new CSST pipe should automatically be grounded along with the rest of the system, right? Sweating it, here... thanks for any opinions, suggestions, or warnings!

  22. Nicole Garcia
    April 7, 2016

    Hi. Is CSST ok for in wall use?

  23. Phyl
    April 15, 2016


    Is CSST ok for use outside of my home? I need to have over 50' run along the exterior of my home if I am going to install a gas stove. Thank you

  24. Joan Buckley
    May 22, 2016

    Hi, We have just finished the beginning of what will probably be a small claims court mess in the upcoming months. We have been in our home just 3 months; started smelling gas a bit, but wasn't sure. Finally had the gas company out and YES - huge leak in our CSST line. But before the certified plumbers could do the work (in the walls - 6 large holes in the dry wall), I had to get an electrician out here to ground the system (I am in Texas) and get a permit. After the work was finished, I had to get a city inspection and then get the gas reconnected. I still need to get the walls painted and patched...9 days without hot water. I cannot even begin to think who I am supposed to turn to in seeking compensation for this. Never again. I am so very grateful that we did not have an explosion or a fire

  25. David
    August 28, 2016

    A gas fireplace was installed in my house several years ago using CSST. It runs along the outside of my house for about 5 feet before entering the fireplace through the brick. I recently noticed that the yellow insulation has now cracked off exposing the pipe. Is there any issues I should be concerned about with the pipe now exposed to the elements (heat, rain, snow)? Can this be fixed without replacing the pipe.

    Thanks in advance!

  26. Karen
    September 2, 2016

    I like the concept of the CSST: my husband has a concern. I would like a flexable line between a fitting and my gas dryer; allowing moving for cleaning behind the appliance plus cleaning the exhaust piping. Input..?

  27. Mary Heffner
    November 1, 2016

    We have a house built in the 1880s. It has the original black iron gas lines, and although a little rusty, they appear to be in good shape. No leaks. We have just had about a 6' section of CSST added inside the house, to the junction where the hot water heater is connected into the gas line. The CSST line runs along the baseboard over to our new gas dryer. I am a little confused about whether it needs to be individually grounded, or if it is already grounded by virtue of being attached to the black iron line. If it does need to be grounded, how would that happen, since it is only a very small section?

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