Retrofit Electromagnetic Shielding of CSST to Mitigate Fires from Lightning Transients, AC Fault Currents, and Ground Potential Rise

Abstract

Corrugated Stainless Steel Tubing (CSST), installed in an estimated 6 to 12 million American homes since 1988, represents a systematically underreported residential fire hazard. The thin CSST wall (0.15–0.25 mm) renders it acutely vulnerable to arc perforation by lightning-induced transients. The industry’s primary regulatory response—bonding CSST to the building’s electrical grounding system per ICC IFGC §310.2—is demonstrated to be physically counterproductive. It communicates Ground Potential Rise (GPR) to the gas tube while leaving the principal proposed arc source unaddressed: an ungrounded array of metallic roof fasteners that accumulate charge toward cloud potential through electrostatic induction, behaving as distributed corona electrodes above the CSST runs below. Drawing on Gauss’s Law, Maxwell’s equations, the coaxial cable shielding analogy, and laboratory perforation testing, this paper develops a physical framework establishing that retrofit electromagnetic shielding —a continuous external conductive enclosure applied from manifold to appliance terminus—is the only engineering measure that simultaneously resolves all three identified arc failure modes: lightninginduced arc initiation from the roof fastener array; GPR-driven jacket breakdown communicated through the bonding connection; and 60 Hz AC fault current arcing from household wiring in shared spaces. Because the retrofit shield intercepts external electromagnetic energy on its outer surface while isolating the gas tube within, it renders the bonding mandate unnecessary and provides the highest degree of protection achievable against the full spectrum of identified arc hazards — a universality of coverage no currently deployed single measure, including arc-resistant CSST products and the bonding mandate itself, can match.