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

By
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

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Topic:
Home Improvement
Location:
Minnesota
Groups:
Ask the Home Inspector
ASHI
Minnesota Real Estate Investor Group
Minnesota Real Estate
Tags:
gas piping
lightning strikes
csst installation requirements
corrugated stainless steel tubing
bonding
bonding csst
csst bonding
csst

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Rainmaker
1,659,657
William Feela
Realtor, Whispering Pines Realty 651-674-5999 No.
WHISPERING PINES REALTY

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.

August 28, 2012 07:30 PM
Rainmaker
229,341
Reuben Saltzman
Minneapolis Home Inspections
Structure Tech Home Inspections

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?

September 01, 2012 03:24 AM
Rainmaker
229,341
Reuben Saltzman
Minneapolis Home Inspections
Structure Tech Home Inspections

Nan - so everything is electric?

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

William - exactly.  This is all about safety.

 

September 01, 2012 03:28 AM
Rainmaker
1,170,453
Jay Markanich
Home Inspector - servicing all Northern Virginia
Jay Markanich Real Estate Inspections, LLC

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.

September 01, 2012 04:05 AM
Rainer
34,147
Judith Clausen
Judith R. Clausen
Buyers Advantage Real Estate of Metro Denver

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!

September 12, 2013 07:37 AM
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Rainmaker
229,341

Reuben Saltzman

Minneapolis Home Inspections
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Home inspection topics in the Minneapolis / Saint Paul area.