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WHAT IS CSST? It is a flexible, stainless steel pipe coated in yellow plastic used to supply natural gas to residential and commercial structures. It is routed through and along floor and ceiling joists in the basement and attic and inside interior wall cavities. It was first developed in Japan in the 1980’s as a safe alternative to rigid black iron gas pipes that often failed and started fires during earthquakes. Sales of CSST began in the United States in the 1990's.

WHAT ARE THE BENEFITS? When traditional black iron pipe is used, a joint needs to be fitted and checked for leaks every time the pipe changes direction. CSST offers flexibility and can be snaked through walls and around obstacles with fittings placed only at the ends of the run. Contractors quickly discovered it could be installed in a lot less time than rigid black iron pipe systems, and code officials appreciated the fact that less fitting joints meant less potential leak paths. Although CSST is more expensive initially than black iron pipe, its overall cost is less when you factor in the cost of labor and installation time.

WHAT IS THE RISK? If lightning strikes near a house, it can result in a power surge than will cause all electrically conductive systems in the structure to become energized. The resulting electricity can puncture a small hole in the wall of CSST allowing natural gas to leak through the house, ultimately causing an explosive fire.

IS THERE A SOLUTION? Beginning in August 2006, all CSST manufacturers added bonding and grounding procedures to their installation requirements. Specifically, there must be a minimum 6-gauge bonding wire between the CSST and the building's grounding electrode, such as a copper cold water pipe, so that the surge will go from the bonding wire to the copper pipe and into the ground rather than damaging the CSST. This improved safety installation requirement reduces the likelihood of an electrical surge that can potentially cause a fire. In addition to protection from fire, bonding will also prevent a possible electric shock to people who come in contact with the gas piping and other metal objects connected to the grounding system. CSST systems installed prior to 2006 may not have the proper bonding for safety.

WHAT SHOULD I DO IF I FIND MY HOUSE HAS CSST? If you find CSST after inspecting your home or business, it is strongly recommended that you determine if the CSST system is properly bonded and grounded. A bonding device, such as those in the illustrations below, should be installed on your natural gas system in order to reduce the chances of a natural gas leak or fire.

Richard D. Malin & Associates: Technical Library

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