If you’ve ever had a home inspection report mention CSST (Corrugated Stainless Steel Tubing), you may have seen a note about “bonding” or even “lack of bonding.” While this might sound like obscure electrician lingo, it’s actually an essential safety measure that can prevent catastrophic damage—or worse. Let’s break down what CSST is, why it needs bonding, how to identify proper bonding, and what risks are involved if it’s not done correctly.
What Is CSST?
CSST is a flexible, stainless steel piping used to distribute natural gas or propane within a building. It’s become a popular alternative to traditional black iron pipe because it’s faster and easier to install—especially in tight spaces or during retrofits.
You’ve probably seen it in homes: a yellow or black flexible gas line snaking through the attic or basement. While CSST is convenient, it’s also more vulnerable to damage from electrical surges—particularly from lightning strikes.
Why Bonding CSST Is So Important
Bonding is the process of creating a low-resistance electrical path to ground. In the context of CSST, it means connecting the gas piping to a home’s grounding system (usually via a grounding electrode or grounded conductor) to reduce the risk of damage from electrical energy—like that from a lightning strike or nearby surge.
If lightning strikes a home or even the ground nearby, the energy can travel through the metal systems in the building. Traditional rigid black iron gas pipe can often withstand this, but CSST is much thinner. Without proper bonding, that electrical surge can puncture the CSST, causing gas leaks or even explosions.
Key point: CSST must be bonded to the home’s grounding system to help safely redirect electrical energy and reduce fire or explosion risks.
How to Identify Proper Bonding
If you’re a homeowner or agent looking to ensure a property is safe, here are some things to look for:
Look for the bonding wire
A properly bonded CSST system should have a copper bonding wire (usually #6 AWG bare or insulated) clamped to:
- The CSST fitting (usually where it connects to the gas meter or manifold), AND
- The grounding electrode system or grounding conductor (often at the main electrical panel or nearby ground rod).
Verify the bonding clamp is properly attached
The bonding clamp should be securely fastened to a metal portion of the CSST system—often at the manifold or first fitting after entering the home. It should not be attached to a flexible portion of the tubing.
Check the manufacturer’s bonding requirements
Not all CSST is the same. Older CSST systems (yellow jacket) require external bonding. Newer systems, like TracPipe® CounterStrike® (black jacket), may have different bonding needs, though most still recommend bonding for extra safety.
Location matters
The bonding point should be as close as possible to the CSST entry point or manifold and must be on the house side of the gas meter (not the utility side). The bonding wire must not be overly long, loosely attached, or disconnected.
What Can Go Wrong If It’s Not Bonded?
Failing to properly bond CSST can lead to serious safety hazards, including:
- Gas leaks from punctures caused by lightning surges
- House fires or explosions if leaked gas is ignited
- Insurance liability if damage occurs and improper bonding is discovered
- Code violations that may delay closings or require costly retrofits during real estate transactions
In fact, the National Fire Protection Association (NFPA) and the National Fuel Gas Code (NFPA 54) have updated standards over the years to require bonding of CSST. Many local jurisdictions also enforce bonding requirements under the International Residential Code (IRC).
What Should Homeowners Do?
If you’re unsure whether your home’s CSST is properly bonded, here’s what you can do:
- Have a licensed electrician evaluate your gas piping system for proper bonding.
- Schedule a home inspection or specialized electrical safety check—especially if your home was built or retrofitted between the late 1990s and early 2010s, when yellow CSST was common.
- Install proper bonding if it’s missing. It’s a relatively inexpensive fix that can prevent massive damage.
Bottom Line
Bonding CSST is a small detail that carries big safety implications. As home inspectors, we always look for proper bonding when we encounter CSST in a home. If it’s not present—or done incorrectly—it’s a red flag worth addressing right away.
Whether you’re a homeowner, buyer, or real estate agent, ensuring CSST is safely bonded helps protect everyone under the roof.
Need a home inspection?
At Nordic, our licensed inspectors check for CSST bonding and dozens of other safety features in every home we inspect. Contact us today to schedule your next inspection! 701.566.1446 ext. 0