New Installation Instructions Announced for Steel Tubing
The manufacturers of corrugated stainless steel tubing (CSST) have issued updated instructions, including an installation requirement that the CSST system be bonded directly to the building grounding electrode system.
CSST is widely used in residential and commercial buildings to carry natural and LP gas within the building structure. Concerns about a possibility that a close proximity lightning strike may cause electrical arching, which in turn might puncture the tubing wall, release the flammable gas and result in a fire, have led to the new installation instructions.
To learn more about the development of CSST gas piping for the residential market and the technical requirements for installation of CSST from its inception to current practice, click here to obtain a copy of a new report prepared by the NAHB Research Center, “Corrugated Stainless Steel Tubing for Fuel Gas Distribution in Buildings and Concerns Over Lightning Strikes.”
Currently, the fuel gas code (NFGC), the electrical code (NEC), the plumbing code (UPC), the ANSI LC-1 product standard for CSST systems and the previously issued manufacturers’ instructions all provide methods for dissipating electrical energy through techniques called bonding and grounding.
The new manufacturers’ instructions for CSST specify that an additional bonding connection must be added between the CSST piping and the grounding electrode system at the point where the gas piping enters the building. The bonding conductor connection must be made with a minimum 6 AWG copper wire. This supplemental electrical bonding is to provide additional protection to the CSST system if it is energized by an indirect lightning strike.
All six CSST manufacturers have issued technical bulletins or other documents to describe the new bonding requirements. It should be noted that the bonding requirements of these manufacturers are not absolutely identical, but in the opinion of the NAHB Research Center, the dissimilarities appear to be inconsequential.
BE ADVISED: the new CSST manufacturers’ instructions are more stringent than current codes. Users of CSST should follow the manufactures’ instructions, but also should coordinate with local code officials to avoid inspection delays that might result from potentially conflicting requirements.
A proposal to modify the bonding requirements for CSST in the 2009 NFGC is currently under review. If the NFGC proposal is accepted and published, the 2011 edition of the National Electrical Code will contain the same provision.
For more information on the new CSST manufactures’ instructions, e-mail Larry Brown at NAHB, or call him at 800-368-5242 x8565, or contact Joe Wiehagen, 800-638-8556.