CSST bonding

What’s the deal with the bonding of the corrugated stainless steel tubing for gas appliances. I have been asked by a Real Estate agent on how and who to reply to a request of a non visible bonding wire to a gas heater with CSST. Many electricians, HVAC techs, builders and inspectors are still not in the loop on this issue. Is the electrician the one to address this issue. I looked on the internet and found this latest article-

I would like to know if and how to include this in my inspections and reporting. It seems like its still up in the air. That’s progress for you!


Bonding is typically established by an electrician. Other tradesmen are not necessarily qualified to determine or establish proper bonding.

The “non-visible” (I’m not sure what you mean by that) bonding wire must have visible and accessible bonding connections.

Not sure what you mean by non visible bonding wire.

IMO the electrician is the one to address the issue.

The CSST must be bonded only at the end nearest the entry of the gas service into the building. If it is bonded at both ends, or at the end nearest the gas-burning appliance, the CSST may carry stray electrical currents or act as a grounding conductor, which can damage the CSST and its fittings, and cause leaks.

Here is a good discussion of the issue.

G2411.2 (310.2) Gas pipe bonding - systems that contain CSST. A gas piping system that contains any corrugated stainless steel tubing (CSST) shall be electrically continuous and shall be bonded to the electrical service grounding electrode system at the point where the gas service enters the building or structure. No portion of the gas piping system shall be used as or considered to be a grounding electrode or a grounding electrode conductor. CSST shall be installed and bonded in accordance with this section G2411.2, and the stricter of: (a) the requirements set forth in the CSST manufacturer’s installation instructions, or (b) the requirements set forth in Sections G2411.2.1, G2411.2.2, G2411.2.3, and G2415.5.

The correct term is “additional bonding”. It should already have the branch circuit ground connected to the little green wire inside the furnace compartment so that is the basic bond that was ok for quite sometime.

Most areas around here started requiring the additional bonding in late 2007 with very strict enforcement. Separate permit required by an electrician in some areas when it first became an issue. Its more expensive to add when the distance from the gas pipe to the ground electrode is long. A second ground rod is not allowed, it must be bonded to the existing ground system for equipotential.

Upgrade recommended: No grounding or bonding found for the gas piping except through the furnace equipment’s ground. This is an accepted method in many areas but recent changes have occurred to the bonding requirements in some areas and upgrades are recommended to enhance the safety level of the home.

The CSST flexible gas piping that is used throughout the house is a common item. A class action lawsuit involved this type of product. The details are available at www.CSSTsettlement.com or 800 420-2916

The product was not recalled but recommendations were made to closely follow the manufactures installation instructions. The instructions are not part of this inspection but likely involve proper bonding methods of the pipe to prevent issues with lightning damaging the thin walled pipe. I recommend having upgraded bonding installed by a licensed electrician, plumber or HVAC person that is familiar with the installation instructions. Typical methods use a #6 solid copper conductor clamped to the black iron main gas pipe at the exterior with the other end clamped to the existing electrical grounding electrode conductor (GEC) that runs to an existing ufer grounding system or the existing grounding rod imbedded in the earth. Upgrade products called gas breakers can also be added inline with the gas piping distribution for a higher safety factor since they are designed to shut off if an unusual flow of gas is present.

Bruce thanks for you good reply. I understand the main bond for the gas steel pipe to the electrical system but the circuit wire to the furnace is no longer acceptable? If we do not see a #6 ground from the furnace to the steel pipe (upgrade recommended).

The regular equipment ground to the furnace is still needed.
The additional bonding would not typically run all the way to the furnace area, it would only go the shortest distance needed to get a clamp on the steel gas pipe. They do make some clamps that go on the CSST fitting joint but no one uses those around here.

Read third paragraph down in http://www.nachi.org/lightning.htm