Flexible Gas Piping And Proper Grounding Of Flexible Gas Piping

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This article details a potential hazard related to Flexible, Yellow, Corrugated Stainless Steel Tubing (CSST) Gas Lines within your home. It also describes a safety hazard and code changes due to the history of house fires associated with CSST when lightning strikes nearby, or worse yet, the home itself.

The risk is tremendously reduced when CSST flexible gas lines are “bonded “ (BONDED DEFINED: Connected with wiring to take electrical current away from CSST flexible gas lines in the event of a lightening-strike on or near the home).  Lightning-strikes have a documented history of creating holes in CSST gas lines, allowing the gas to escape and dramatically increasing the risk of gas-fueled fires in the home. Confined gas fumes that are in a closed room or an unoccupied home can lead to an explosion.

Connecticut Building Code has allowed CSST gas lines since the 1990’s. Building Codes requiring bonding of CSST flexible gas lines came into practice no earlier than 2007. This code came in as a response to damage to flexible gas lines and fires in homes struck by lightning. As you can see, there is a significant multi-year gap in which Building Codes did not require proper bonding of flexible gas lines.  Building Codes, including Plumbing & Electrical Codes were updated based on the growing incidents of house fires.

Homes built with CSST flexible gas Lines before the Building Code required bonding were built correctly to the Building Code at the time they were built.  BUT that does not mean they are safe.  These homes may, or may not have bonded gas lines.  Only an inspection will determine if the gas lines are safely bonded as required by today’s Building, Plumbing & Electrical Codes.

If you own a home that has CSST flexible yellow gas lines and was built prior to 2007, this fire-risk may exist in your home.  Most homes have gas lines in their attic, walls & basements.  CSST flexible gas lines in the attic are a prime candidate for damage from lightning strikes. Especially if they are not protected with Bonding to ensure electrical energy is carried away from the pipe (versus carried by the pipe).   The home needs to be inspected, and proper bonding (if not already present) must be installed to yellow flexible gas lines to help protect the home in the event of a lightning strike. Many fire experts are confident that a lightning strike’s electrical-energy can run through the electrical wiring in a house, then jump (or arc) onto CSST gas lines where it creates holes into the tubes, releasing gas & possibly creating a gas-fueled fire and / or explosion.

There are documented incidents where severe lightning has struck homes. A lightning strike to a steel chimney cap, can extend into the house.   For instance; Lightning can enter the home through a metal chimney cap extending the electrical-energy through copper electrical wiring, copper water piping, the wooden structure itself and, if available and not protected, the flexible CSST gas line.  Electricity will take the easiest path or the path of least resistance. If a lightning strike is large or close enough, the electrical current can jump between products in search of the ground.

lightning struck CSST
lightning struck CSST

In some areas, as of 2015 Home Inspectors became required to notify their clients (in writing & on the inspection form) of the presence of CSST gas lines that do not have proper bonding.

If you own a home built since 1990, your home may have unbonded flexible gas lines.  Many homes have gas lines in their attic and buried in walls.  If your concerned, the home needs to be inspected, and (if not present) proper bonding must be installed to CSST gas lines, to help protect the home in the event of a lightning strike.

Gas Coming to your Home

Underground natural gas lines are primarily polyethylene.  Propane lines coming to the home are either copper or polyethylene. Polyethylene flexible gas piping is engineered and certified for underground installations.  These lines are made in many sizes, from quite large to residential-service lines going to individual homes or a home’s exterior equipment like pool heaters or backup generators.

The dielectric yellow jacket is believed to actually increase this problem.  In response, some manufacturers of CSST flexible gas piping now have black coated versions that are more resistant to lightning strikes.

CounterStrike® or FlashShield® is a patented CSST innovation based on existing yellow CSST flexible gas piping products.  It is engineered to significantly decrease the potential for lightning-induced damage to fuel gas piping systems IF, installed correctly.

CSST FlashShield

This verbiage ss from the TracPipe Manufacturer: “TracPipe® CounterStrike® is a patented CSST innovation that is engineered to significantly decrease the potential for lightning induced damage to fuel gas piping systems. TracPipe® CounterStrike® has been designed with a proprietary jacket material in place of the standard yellow jacket. This black jacket has energy dissipating properties that will help protect the TracPipe® CounterStrike® stainless steel pressure liner as well as other fuel gas system components if the TracPipe® CounterStrike® becomes energized due to lightning.”

** NOTE: This is not an endorsement of this product by JNR Plumbing LLC. This information is provided only as a courtesy to our readers.**

There are documented fire inspections where it was believed a lightning-strike caused damage to unbonded CSST, resulting in gas-fueled fire damage.  In response, CSST manufacturers developed electrical bonding requirements staring as soon as 2007.  Their testing shows bonding will largely mitigate the risk for only “indirect” lightning strikes (those that do not hit the home).   Yellow flexible gas lines were used in the testing.

Bonded Gas Line Example

Electrical Bonding Must Be Present In Homes With Csst Gas Lines — to Reduce The Risk Of Fire Or Explosion Resulting From Damaged Gas Lines In The Event Of A Lightning-strike 

CSST flexible gas piping must be bonded to reduce the risk of damage due to a lightning strike on the home.  The most common issue that home inspectors find is the CSST system is not being properly bonded.

Improper Bonded Gas Line Example
You can see that the bonding clamp is over the yellow sheathing which will not enable a proper bond.

When this type of gas-distribution system is installed, without being properly bonded to current standards, there is an increased risk for damage.  A Damaged gas or propane line can leak gas, causing a fire and / or explosion.  All manufacturers of CSST began implementing Specific Bonding Requirements as soon as 2007.

What about existing homes? Building-Codes have something called ‘grandfathering’.   This means when something was installed in compliance to Building-Codes at the time of the installation — it is deemed correctly installed moving forward in time, even if Building-Codes change significantly.

If CSST was installed (in compliance to code) before CSST manufacturers had made the special requirements for bonding, that installation still meets code today.   A Home Inspector will (or should) specify the need for a safety-upgrade based on today’s Building-Codes and Safety-Practices.  ** This should not be confused with unbonded CSST flexible gas lines being safe. Only that it met building code requirements at the time it was installed.

Proper CSST Bonding

CSST Bond Wires or Clamps Shall NEVER Be Connected to:

  • Natural gas meters or facilities.

  • A ground that is independent of the electrical service grounding system.

  • The corrugated stainless-steel portion of the flexible CSST pipe (Clamps must be attached to: the brass fitting, steel manifold, or other rigid steel pipe).

CSST bond wires or clamps shall ALWAYS be connected to:

  • Customer piping — as close to the natural gas meter as practical.

  • A CSST brass fitting, a steel manifold or rigid pipe component connected to a CSST fitting.

  • The electrical service grounding system.  This connection may be made at either: the ground rod, the ground-wire running to the rod, or in the electric service-panel (also known as Circuit-Breaker Box or Panel).

Properly bonded gas pipe
Properly bonded gas pipe

CSST Gas Lines Versus Flexible Appliance Connectors

There is a difference between CSST Gas Lines and the similar looking yellow Flexible Appliance Connectors (to be known here out as “FAC”).  While both CSST and FAC are made with stainless steel & carry gas — that’s where their similarities end.  CSST is a Gas-Distribution System.  FAC is a short length of tubing designed to connect the gas-distribution pipe to the gas-burning device.

FAC Connector
FAC Connector


How else to Identify FAC:

  • FAC does not require bonding. This is because they are connected to a bonded (if properly installed) gas-distribution system.

  • It is between 1–6 feet long.

  • FAC are commonly found between the home’s gas-supply lines and the gas equipment OR appliance.

  • FAC corrugation is highly visible.  As compared, CSST is sheathed and the corrugation is not highly visible.

We at JNR Plumbing LLC want our clients and our readers to understand the safety involved within your home. We do realize that Bonding must be installed by a licensed professional, particularly an Electrician. We do not expect Electricians to know what pipes and which pipes require Bonding which is where your licensed Plumbing contractor, or home inspector can provide. If you need a licensed professional to look over your gas piping and the installation of your gas piping, feel free to give us a call. After all, we only have licensed technicians specifically trained in servicing residential homes and commercial properties.

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