Forget Code: CSST gas lines need bonding to reduce the risk of a fire.

Home Inspector with Structure Tech Home Inspections

If you own a newer home or you've recently had gas lines added to your home, there's a good possibility that Corrugated Stainless Steel Tubing, or CSST, was used.  This is a relatively new material that is approved for the distribution of natural gas inside of homes.  The best analogy I can think of to describe this material is that CSST is to steel gas pipes what PEX is to copper tubing, or Romex® is to rigid metal conduit.

CSST needs to be bonded.  The most common issue that home inspectors find with CSST is a system that hasn't been properly bonded.  When CSST is installed without being properly bonded to current standards, there is an increased risk for damage to the material from a nearby lightning strike.  When CSST is damaged, it can leak gas and cause an explosion and/or a fire.  To the best of my knowledge, all manufacturers of CSST began implementing specific bonding requirements around 2007.  Of course, proper bonding won't make CSST immune to damage from a nearby lightning strike, but it will reduce the risk of damage.

What about existing installations?  Building codes have something called 'grandfathering'.   This means that if something was installed to code, it's still a code compliant installation today, even if the codes have changed significantly.  The nice thing about being a home inspector is that we don't need to get hung up on code requirements.  If something is deemed unsafe due to a change in accepted residential construction standards, our Standards of Practice require us to recommend repair.

If CSST was installed to code in 2005 and the manufacturer didn't have any special requirements for bonding at the time it was installed, the installation still meets code... but that won't stop a home inspector from recommending the system be bonded to today's standards.   The manufacturers of CSST have changed their installation requirements because they've learned that the old methods weren't good enough.

What does proper bonding look like?  All manufacturers of CSST require the systems to be bonded in a specific manner - there needs to be a separate ground wire connected either to the rigid gas piping before the CSST, or directly to one of the CSST nuts.   The diagram below shows an example of what this would look like when properly installed to today's standards.

Bonding CSST diagram

The photo below shows an example of CSST bonded at the exterior of the home, with the bonding clamp connected to the CSST nut.

CSST Bonded at nut

The video below, produced by Gastite, shows a couple examples of how to properly bond CSST.

Note: some second generation versions of CSST, such as CounterStrike, do not have any additional bonding requirements.

How would you know if you had CSST in your home?  Look for flexible tubing with a yellow jacket that covers the ridges.  It's doesn't have to be yellow - for instance, CounterStrike has a black jacket, but the majority of CSST in Minnesota has a yellow jacket.  I've never seen any other color in person.  This material is not to be confused with an appliance connector, which might have a yellow coating that follows the contours of the ridges.  The photo below shows the two different materials.

CSST vs Gas Connector

The bottom line is that if you have a home with CSST, you should make sure it's properly bonded to today's standards, regardless of whether the installation 'met code' when it was originally installed.  You can't grandfather safety.

Additional Information on CSST and bonding

Comments (18)

Roy Kelley
Retired - Gaithersburg, MD

Good information for home owners.

Enjoy the final days of summer with your camera in hand.

Aug 27, 2012 08:19 PM
Lenn Harley
Lenn Harley,, MD & VA Homes and Real Estate - Leesburg, VA
Real Estate Broker - Virginia & Maryland

A large home in my area, built in about 2006, did suffer severe fire damage following a lightening strike on the propane gas system connection at the house.  The house had to be completely rebuilt from ground up.



Aug 27, 2012 08:21 PM
Reuben Saltzman
Structure Tech Home Inspections - Minneapolis, MN
Delivering the Unbiased Truth.

Roy - I fully intend to.  Thanks.

Lenn - scary!  I assume it had CSST gas tubing?

Aug 27, 2012 08:26 PM
James Quarello
JRV Home Inspection Services, LLC - Wallingford, CT
Connecticut Home Inspector

TracPipe no longer manufactures the yellow CSST after losing a class action law suit. I have begun seeing the black sheathed "safer" version of CSST on newer installs. 

Aug 27, 2012 09:34 PM
Reuben Saltzman
Structure Tech Home Inspections - Minneapolis, MN
Delivering the Unbiased Truth.

James - I wonder how long it's going to be before the other manufacturers follow suit?

Aug 27, 2012 09:41 PM
Wayne Bennett
One Home Team Realty/Charlotte,NC 704-293-3931 - Charlotte, NC
Real Estate...As It Should Be

Reuben...I recently cosed on a home where the home inspector had in the report that the CSST gas line needs bonding.  The seller refused to pay for this.  In order for the deal to close I had to reduce commission.  If the house was built to code a few years ago and the CSST wasn't bonded, what were the risks?

Aug 27, 2012 10:08 PM
Michael Setunsky
Woodbridge, VA
Your Commercial Real Estate Link to Northern VA

Reuben, this just makes sense. Did they assume because it was buried, it didn't need to be bonded?

Aug 27, 2012 10:18 PM
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

The other day, on new construction (!), I found that the unbonded line leading from the gas meter to the indoor gas manifold was TracPipe, but the rest of the house was Counterstrike!  You have to wonder.

Great post Reubs.  Great links too.  You give the same links there that I do on my reports!

Aug 27, 2012 10:27 PM
Harry F. D'Elia III
WEDO Real Estate and Beyond, LLC - Phoenix, AZ
Investor , Mentor, GRI, Radio, CIPS, REOs, ABR

And this is why we have city code so we can follow it to avoid accidents

Aug 27, 2012 11:13 PM
Charles Buell
Charles Buell Inspections Inc. - Seattle, WA
Seattle Home Inspector

Still tons of it around here but of course we barely know what lightning is around here :)  I have also never seen CSST run outdoors.  I don't think there is anything wrong with it---they just don't do it that way around here.

Aug 27, 2012 11:44 PM
Nan Jester
Exit Real Estate Gallery Jacksonville Beach, FL - Jacksonville Beach, FL
Realtor, Exit Real Estate Gallery

Unfortunately, in this area there is hardly a gas line to be found. Guess the coal industry out lobbied them.

Aug 28, 2012 12:29 AM
Donald Hester
NCW Home Inspections, LLC - Wenatchee, WA
NCW Home Inspections, LLC

Reuben, I see quite a bit of this, propane fireplaces mainly. I almost never see it bonded correctly. Like Charlie there I never see on the exterior of a home.

Aug 28, 2012 02:09 AM
William Feela
Realtor, Whispering Pines Realty 651-674-5999 No.

Very good points.   Some people thing that if it ain't broke leave it alone. but that isn't always the right thing to do.

Aug 28, 2012 12:30 PM
Reuben Saltzman
Structure Tech Home Inspections - Minneapolis, MN
Delivering the Unbiased Truth.

Wayne - when CSST is installed without being properly bonded to current standards, there is an increased risk of damage to the material from a nearby lightning strike.  When CSST is damaged, it can leak gas and cause and explosion and/or a fire.

Michael - in one recent case, they assumed that because the installation was approved by the building official in 2005 that nothing else needed to be done.

Jay - I'm glad to hear your starting to see counterstrike.  Sounds like a much better product. I still haven't seen it in person yet.  

Harry - that's the idea :)

Charles - I assume they use steel at the exterior?

Aug 31, 2012 08:24 PM
Reuben Saltzman
Structure Tech Home Inspections - Minneapolis, MN
Delivering the Unbiased Truth.

Nan - so everything is electric?

Donald - do they protect the CSST coming in to the gas fireplaces?  

William - exactly.  This is all about safety.


Aug 31, 2012 08:28 PM
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

I have been seeing Counterstrike for about 6 months now.  What I don't know is this:  on this house, for example, there was no bonding and they used TracPipe from the meter to the manifold.  Then Counterstrike everywhere else.  Does Counterstrike, as advertised, work in that scenario to lessen the lightening danger?  I might contact Omegaflex to see what they say.  I bet they won't answer me.

Aug 31, 2012 09:05 PM
Judith Clausen
Buyers Advantage Real Estate of Metro Denver - Denver, CO
Judith R. Clausen

Thanks for posting this article, Reuben! The issue just arose with a purchase by my client. Our inspector tagged it, the listing agent had NO clue, had never heard of it, called 3 HVAC contractors who all said it didn't need to be fixed. Our inspector was going to check with someone he knew who could fix it but came down with the flu and was out of commission. So I found this post, sent it to the listing agent who showed it to her HVAC contractor. They said they'll fix it now that they know how (!). We'll be going back to see whether they did. Since our inspector is still under the weather we'll take photos and text them to him for his review before we close on the place. 

My kids live in Minneapolis, so when they buy their next house you're the man!

Sep 12, 2013 12:37 AM

So what is the bottom line on houses built prior to the NFPA 54 code requiring bonding. It is the right thing to do but does it have to be done. Our house was built in 2007, I believe the 2009 was when most of the bonding codes for CSST were revamped.

Jun 30, 2016 11:06 PM