Reuben Saltzman

CSST Bonding Update

Post Edit: Check out my latest post on this topic from 11/22/16:

I last blogged about CSST bonding nearly three years ago.  There have been a few changes to CSST bonding rules since then, and there is still a lot of bad information circulating about CSST bonding and safety requirements, so it’s time for an update on that topic.

First, a primer on CSST, which stands for Corrugated Stainless Steel Tubing.  If you own a newer home or you’ve recently had gas lines added to your home, there’s a good possibility that CSST was used.  This is a relatively new, flexible 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.

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 requires us to report on it.

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 today.   That won’t stop me from recommending this important safety upgrade, however. I’ll still recommend having the system 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. There is an unacceptable risk of fire from a nearby lightning strike with older systems.

What does proper bonding look like?  There needs to be a separate bonding wire connected either to the rigid gas piping before the CSST, or directly to one of the CSST nuts.   This is needed any time CSST is installed, even if it’s just a small amount.  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 other end of that wire shown above went into the main electric panel.  The video below, produced by Gastite, shows a couple examples of how to properly bond CSST.

While the old method for bonding CSST required a connection at the main electric panel, this is no longer required in Minnesota.  Minnesota’s 2015 Fuel Gas Code uses the 2012 International Fuel Gas Code, which requires CSST to be bonded anywhere along the electrical service grounding electrode system.  That means that the bonding conductor for CSST can be connected to the metallic water piping coming into the home, a ground rod at the exterior, or anywhere else on the service grounding electrode system.  This change makes it much easier to properly bond CSST.  To view the current requirement, click the following link to view Chapter 3 of the 2015 Minnesota Fuel Gas Code, and scroll all the way down to the bottom to view section 310.1.1.

Some manufacturers of CSST offer a product with a black outer “arc-resistant” jacket, which is designed to show that it’s an arc-resistant product.   Two such examples of these products are CounterStrike and FlashShield.  While the manufacturers of these products do not require special bonding, the Minnesota Fuel Gas Code makes no exception to the bonding requirements for these products.  They still need to be bonded.  For more info on that topic, check out this document on CSST bonding from Pro-Flex.

How can you know if you have CSST in your home?  Look for flexible tubing with a yellow or black jacket that covers the ridges.  About 99% of the CSST I’ve seen has a yellow jacket.  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.  Also, if your electrician tells you that bonding the CSST may increase the risk of a lightning strike or is safe because it meets code, simply thank them for their time and call a different electrician.

Additional Information on CSST and bonding

Also, here’s an old news clip with me talking to Kare 11 news about CSST bonding:

Author: Reuben SaltzmanStructure Tech Home Inspections


4 responses to “CSST Bonding Update”

  1. Fred Buck
    May 17, 2015, 1:50 pm

    Please review page 1 of the information found at:

    Direct lightning strike testing was not included in this report.
    Bonding safety should be fully considered by understanding the differences between indirect and direct lightning strikes. Fire safety and risk should be accessed by the home occupants. Full knowledge of this subject is advised. Caution and proper evaluations are essential.

  2. Ann
    May 20, 2015, 7:32 pm

    Can you tell me what is a reasonable price to have the CSST bonded? I am trying to sell my town home that was built in 2004 and the inspector stated that the CSST needed to be bonded as it was a safety concern

  3. George Miller
    May 21, 2015, 9:17 am

    Please be aware in the bonding of CSST that the Electrically Continuous statement must be followed at all times. A cold water copper pipe alone is not considered electrically continuous (Ask any electrical inspector to define that). The cold water pipe “bonding wire” may be attached to with means of a split bolt connector (AKA “bug”) to provide the Bond to the grounding electrode conductor. In addition stranded wire should be considered and use of #4 stranded is reccomended for an average home with a 200 amp service. Remember it is stray voltage and indirect lighting strikes that we want to dissipate. Follow the lighting protection charts in the NEC NFPA70 code book.

  4. New Radon Rules for Minnesota | Structure Tech Home Inspections
    May 26, 2015, 4:34 am

    […] CSST bonding update for Minnesota […]

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