Question: Corrugated stainless steel tubing
I recently received a corrugated stainless steel tubing (CSST) manufacturer’s technical bulletin in the mail that I understand was mass mailed to a lot of electrical inspectors all around the country promoting the need to bond CSST due to lighting strikes. Has UL listed any CSST? Does UL list connectors to bond CSST?
Answer
As of this writing (June 2007), UL has not Listed any CSST or any grounding or bonding fittings intended for use on hexagonal shaped CSST fittings intended to bond CSST. Corrugated Stainless Steel Tubing (CSST) is a flexible corrugated tubing made of stainless steel with a polymeric jacket that is used in many areas of the country for distribution of natural gas. The technical bulletin in question recommends the use of a ground clamp secured around the hexagonal compression nuts on CSST fittings to bond the CSST gas piping system to the grounding electrode system.
UL Lists ground clamps under the product category Grounding and Bonding Equipment (KDER), located on page 172 in the 2007 White Book. Ground clamps are intended for use with ground rods and/or pipe electrodes in accordance with the NEC and are marked with the size of electrode and electrode grounding conductor with which the clamp is intended to be used. Clamps suitable for use on copper water tubing are marked ‘‘Copper Water Tubing,’’ or the equivalent, preceded or followed by the size of tubing. Ground rods, pipe electrodes and water tubing trade sizes are stated in fractions, such as 1/2, 5/8, etc. They have not been evaluated for use on hex nuts for CSST fittings.
If in the future, UL promulgates a Listing of bonding clamps for CSST, UL’s Regulatory Services Department will issue an email notification through its Ultimate Email notification system. If you aren’t currently an Ultimate Email subscriber and would like to be notified if a clamp for bonding of CSST is Listed, please logon tohttps://ul.com/regulators/contact.cfmand register for Ultimate Email and select gas and electrical as your interest areas.
