CSST

Corrugated stainless steel tubing comes on a reel and bends around framing, so a plumber runs one length from the gas manifold to an appliance. Rigid black iron has to be cut, threaded, and fitted at every turn. That speed is why CSST sits behind the drywall of most new Arizona homes. The trade-off is the wall. CSST is thin where black iron is heavy, and that thinness drives the one extra rule it carries.

Section G2411 of the 2021 International Residential Code requires yellow CSST to be bonded straight to the home's grounding electrode system. The bonding jumper is 6 AWG copper at a minimum and can run no more than 75 feet from the gas pipe to the ground connection. The clamp lands on a metal pipe, a pipe fitting, or a brass CSST fitting. It never grips the corrugated tubing itself.

Lightning is the reason, which is what makes the rule earn its keep in an Arizona monsoon. A strike near the house pushes a large voltage onto every metal system inside. If the gas tubing sits at a different voltage than a nearby duct or water line, the difference can arc across the gap, burn a pinhole through the thin CSST wall, and light the gas behind it. Bonding puts both on the same ground, so no gap is left to jump.

For example, Pinal County writes the rule into its own gas piping bulletin: a system containing CSST needs a jumper no smaller than 6 AWG copper. On natural gas the jumper lands downstream of the meter. On a propane lot near Rio Verde it lands past the second-stage regulator. Black arc-resistant CSST is built to take the hit and gets treated differently, but splice in one piece of yellow tubing and the bond comes back. The trap on a real job is that the plumber sets the tubing and the electrician lands the bond, so put that connection on somebody's scope in writing.