CSST Bonding
Corrugated Stainless Steel Tubing (CSST) has gained popularity as a flexible and efficient alternative to traditional rigid gas piping. While CSST offers numerous advantages, including ease of installation and cost-effectiveness, it also requires careful attention to safety considerations. One critical aspect of CSST installation is the addition of an extra bonding connection when using yellow-jacketed CSST. In this article, we will explore what bonding is and when exactly CSST needs to be extra bonded, and when it doesn't.
What is electrical bonding?
Bonding is the process of joining two or more electrically conductive materials together which then connect to the home's grounding electrode system. In our discussion, we are focusing on the connection of CSST gas piping to a home's grounding system. Connecting the bonded items to the grounding electrode system places everything at the same electrical potential and ensures an effective, safe path for stray voltage caused by a nearby lighting strike or ground-fault. Even if not directly struck, CSST can become energized by a nearby lightning strike and can arc to another conductive material within the home. When this happens, yellow-jacketed CSST has been known to sustain pin-sized holes due to the arcing event and the energy involved, creating a dangerous situation where gas can freely flow out.
Do all types of gas piping need to be bonded?
It is important to point out that what we are talking about here is an extra, additional bonding that is required when there is any yellow-jacketed CSST located in the gas piping system of a home. This extra bonding conductor typically attaches to the rigid piping just prior to where the CSST starts at the gas meter or at the CSST rigid end connection piece. The bonding cannot occur at the corrugated stainless steel part of the piping. The typical connection point is shown in the first image below. The copper bonding wire here then connects to the grounding system at the electrical panel. While other types of gas piping are required to be bonded to the home's electrical system, this is usually achieved by the equipment grounding conductor that is part of the electrical connection for an appliance to which the gas piping is connected. Huh? Let me provide an example. If the only gas piping in a home is rigid metal that connects to a furnace, the equipment grounding conductor (the bare copper ground wire) that is part of the furnace's electrical connection will serve as the means of bonding to the home's grounding system. In that case, no additional bonding is required.
What about CSST that has a black jacket instead of a yellow jacket?
CSST manufacturers have responded to the deficiencies of traditional CSST by creating an arc-resistant form of jacket. This type of CSST is identified by its thicker black jacket around the corrugated stainless steel. The use of this type of CSST does NOT require additional bonding.
The electrical inspection done at the time of construction would make sure that my gas piping is bonded properly, correct?
Not necessarily. CSST has been around since the 1990's, but it wasn't until 2006 that manufacturers started to require that their yellow-jacketed gas lines be bonded, and it wasn't specifically required in code until the 2009 code version. Additionally, it is possible that yellow-jacketed CSST could have been added to an existing rigid pipe system along the way by a previous owner, perhaps without a permit, that would now need to be bonded after the initial electrical permit years prior. If your home has any yellow jacketed CSST and you don't see any obvious bonding to the electrical system, you should contact a qualified electrician to evaluate your system and make any needed modifications.
That's it, until next time. Take care.