Are Flexible Gas Lines Safe to Use in Your Home?

Allie Ogletree
Written by Allie Ogletree
Updated July 22, 2022
Father and daughter spending time together in their living room
Photo: Cavan Images / Cavan / Getty Images

If properly installed, your chance of a fire from CSST is as rare as a lightning strike

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Many homeowners scratch their heads when they see bending yellow gas lines in their homes instead of the traditional black steel pipes. If your house was built in the United States between the early ’90s and mid-2000s, you likely have natural gas piping made from corrugated stainless steel tubing—a popular, flexible replacement for black steel pipes. While the upgrade is less likely to leak gas, corrugated stainless-steel tubing can lead to major house fires—if struck by lightning. 

What Is a Flexible Gas Line?

If you’re wondering what the hype is with flexible gas lines, let’s clear some things up. Flexible gas lines are made from corrugated stainless-steel tubing (CSST). These extremely flexible pipes are made from stainless steel and often come coated in a trademark yellow casing, though they can sometimes be black. This clever revamp of the traditional black steel pipes allows natural gas to travel to your fireplace, furnace, stovetop, and any other appliances that use natural gas.

Are Flexible Gas Lines Dangerous?

In short, flexible gas lines are perfectly safe as long as they’re properly installed. A CSST that is not correctly grounded or bonded can leak natural gas or become ignited, leading to a major fire hazard. 

Let’s look at exactly why that happens: CSST is extremely thin compared to the traditional 4 mm black pipe. At about 0.2 mm, or the thickness of two sheets of paper, the odds of lightning surging through improperly grounded and bonded CSST rise. If this happens, the electricity from the lightning can arc, puncture a hole in the line, ignite the gas inside, and cause a fire.

The Risk of House Fires

When it comes to house fires, you shouldn’t worry—obsessively at least—about your CSST. According to the U.S. Fire Administration, cooking is by far the number one cause of house fires nationwide, making up 50.2% of residential fires. Lightning strikes are much rarer, accounting for only a portion of the 1.8% of residential fires caused by natural disasters. Those odds are even lower if you look at how many lightning strikes lead to fires via CSST.

That said, when CSST pipes burst, the pipe turns into a potential giant lightning rod. If the CSST isn’t properly bonded electrically, this can lead to a disaster.

It’s important that you have your home inspected by a local pro, especially if you aren’t sure about the status of your gas lines.

How Do You Know if Your Home Has CSST?

A view of a yellow CSST flexible gas line
Photo: Serhii Ivashchuk / iStock / Getty Images

Speaking of the status of your gas lines, knowing which kind you have is key to determining whether or not your home is at risk of a gas line fire or leak. 

To see if you have CSST, look for long stretches of yellow-jacketed, flexible tubing in your basement, crawlspace, or attic. The short flexible connector to your gas-fired stove, furnace, or hot water heater is not CSST.

How Long Does a Flexible Gas Line Last?

CCST usually lasts about 30 years. This is a long time, no doubt, but not as long as traditional black steel pipes, which can last up to 75 years.

How Much Does It Cost to Inspect and Replace Existing CSST?

Correcting an existing installation can cost as little as $100, while replacing CSST with black pipe can cost several thousands of dollars. In general, expect an estimated quote of $250 to correct the existing CSST and about $4,000 to replace it.

To get a quote, contact a local home inspector or licensed electrician near you to inspect your gas lines. Tell them you think you have CSST and that you want to make sure it's been properly grounded.

Keep in mind running, installing, or repairing a gas line often involves two different fields of expertise. You may very well need to hire a local gas plumber to install the actual gas line and hire an electrician to handle the electrical circuit if any repairs are necessary.

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