If your home was built after 1990, or if it has had any upgrades that included the installation of any new gas lines, then it is possible that there is a potentially-dangerous gas line in your home. Corrugated Stainless Steel Tubing – or CSST for short – is a gas line that has been installed in millions of homes in the US since about 1990, and it is blamed for several house fires every year throughout the country – particularly in areas that are more prone to lightning storms.

CSST was invented in Japan in the 1980s. It was a great alternative to rigid gas lines in Japan where there is a high degree of seismic activity. The flexibility of CSST allows gas appliances to move during earthquakes without the gas line rupturing or leaking. In the 1990s, plumbers began using CSST in the US, and it gained popularity and began to be installed in more and more homes.

It wasn’t long before several house fires were linked to the CSST in the home. According to investigators, lightning strikes caused small pinholes in the CSST piping, and the resulting gas leaks caused the fires. Lightning strikes can create high voltages in metal piping and wiring such as electrical wiring, metal water piping, etc.

Mike Morgan, owner of Morgan Inspection Services in Abilene, Texas, explained that because CSST is so thin (about the thickness of four pieces of paper), it is much more susceptible to damage than other materials, and because it is carrying flammable gas, it can make for a dangerous situation. As the high voltage in the CSST discharges by “jumping” across to some other nearby piece of metal, the “spark” produced is very hot and essentially melts a pinhole through the thin CSST tubing.

Over the years, several things were tried in an attempt to protect homes from the risks of CSST. One solution was that some municipalities and some states completely banned the use of CSST. (Most, if not all, of these bans, have been lifted.) Eventually, in 2006, the ultimate solution that was developed was to electrically bond the CSST in order to prevent the high voltages from building up in the CSST gas line. Studies have shown that bonding the CSST has indeed decreased the number of house fires caused by lightning, but it has not completely eliminated them.

How dangerous is CSST?

Although it has been installed in millions of homes, the number of fires caused by CSST is relatively small. Also, according to the National Fire Protection Association (NFPA), there are between 300,000 and 400,000 house fires in the US every year. Statistics show that only about 1% of these fires are caused by lightning, and less than half of lightning-caused fires are blamed on CSST. These numbers show that while CSST does present a risk to your home, it is not a large risk. There are a lot of things that put your home more at risk of fire than does CSST. CSST may be the largest fire risk in your home that you have never heard of.

Studies show that the main causes of house fires are cooking equipment, heating equipment, smoking in bedrooms, electrical problems, and candles. This does not mean that you should not worry about CSST, and, fortunately, improving the safety of the CSST in your home is a relatively simple thing to do. A licensed electrician can bond the CSST in your home relatively quickly.

How do you know if you have CSST in your home?

Mike Morgan, who has been inspecting homes for more than 17 years, stated that “CSST is a corrugated tubing almost an inch in diameter, and it almost always has a yellow plastic coating on it. Do NOT confuse CSST with the smaller, shorter yellow gas lines running from the gas valve to your furnace, water heater, and stove. These gas lines are not CSST and are safe. One of the best places to look for CSST is in your attic, basement, or in the crawlspace underneath your home.”

If you are unsure if you have CSST in your home, a licensed plumber or electrician should be able to do a quick inspection and let you know. If you do have CSST, don’t panic. Simply call an electrician and have them determine if it is already bonded or not, and if not, have them bond it.