Corrugated stainless steel tubing carries gas efficiently through Metro Vancouver homes, but code requires it be electrically bonded for a specific safety reason.
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Quick answer
CSST (corrugated stainless steel tubing) must be bonded to the home's electrical grounding system because its thin, corrugated wall can be punctured by an electrical arc, such as one caused by a nearby lightning strike, in a way that rigid black iron pipe generally resists. Bonding gives that stray energy a safer path to ground, reducing the chance it arcs through the tubing wall. It's a code requirement in BC, not an optional upgrade, whenever CSST is used.
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Corrugated stainless steel tubing is a flexible, thin-walled gas pipe that's become common in newer construction and renovations because it can be routed through joists and walls with far fewer fittings than rigid black iron. Fewer fittings means fewer potential leak points and faster installation, which is why it shows up often in additions, suite conversions, and tankless water heater installs where routing a rigid line would mean multiple elbows.
The tradeoff is wall thickness. CSST's corrugated stainless wall is thinner than black iron pipe, and testing after lightning-related incidents in various jurisdictions showed that an electrical arc, even one from a nearby strike rather than a direct hit, could burn through the tubing wall at a fitting or bend if the system had no dedicated path for that energy to reach ground.
Bonding connects the CSST system to the home's electrical grounding system using a properly sized bonding clamp and conductor, installed at the point the tubing enters the gas piping system, not just anywhere convenient. This gives stray electrical energy, from a lightning event or a fault elsewhere in the wiring, a low-resistance path to ground that doesn't involve arcing through the tubing wall itself.
It does not prevent lightning from striking the house, and it isn't a substitute for proper electrical grounding elsewhere in the home. It's a specific, code-mandated protection for one identified failure mode of one specific piping material.
Where CSST is installed, BC code and manufacturer installation instructions require bonding as part of a compliant install, sized and located according to the applicable electrical and gas codes. This isn't left to installer discretion, and a Technical Safety BC gas fitter installing CSST is expected to include bonding as part of the job, not as an add-on the homeowner has to separately request.
If CSST is present in a home and a gas fitter can't confirm it's properly bonded, that's flagged during any service call, inspection, or appliance changeover as something to correct, even if the original installer's work is otherwise unrelated to the current job.
If you're buying an older home, adding an appliance, or just curious what's in your walls, it's worth asking whether any gas piping is CSST and, if so, whether bonding is present and intact. This is especially relevant after renovations where an electrician and a gas fitter worked somewhat independently, since bonding sits at the boundary between the two trades and can be missed if neither assumes responsibility for it.
| Situation | What to Confirm |
|---|---|
| CSST installed during original construction | Bonding clamp present at the correct connection point, conductor intact |
| Renovation added CSST branch line | New bonding tie-in done, not just relying on an old bonding point elsewhere |
| Older home, unknown piping material | Ask your fitter to identify pipe type during any gas service visit |
| Panel upgrade or rewiring done separately | Confirm CSST bonding wasn't disconnected or left floating during the electrical work |
Lightning activity here is lower than in many other parts of North America, but bonding requirements in BC code aren't written around local strike frequency, they're written around the failure mode of the material itself, including stray current from other sources. A basement suite conversion or laneway home addition that runs CSST from the main house gas line is exactly the kind of project where bonding gets missed if the electrical and gas work aren't coordinated.
This is a case where a small, inexpensive detail at install time is far cheaper than discovering it's missing later. A licensed gas fitter should verify and document bonding as a standard part of any CSST installation or gas system inspection.
Safety note
If you ever smell gas, hear a hissing sound near a gas line or appliance, or suspect a leak, leave the home immediately and call from outside. Do not flip switches, light anything, or use a phone inside the house. Call FortisBC at 1-800-663-9911 to report a suspected gas leak or carbon monoxide concern before doing anything else. Gas piping, venting, and combustion appliance work in BC must be done by a Technical Safety BC licensed gas fitter; CANRO holds gas licence LGA0043870 and boiler licence LBP0046450.
Not when it's installed and bonded correctly. CSST has a different vulnerability than rigid pipe, and bonding is the specific mitigation for it. Properly bonded CSST is a code-compliant, widely used material.
You can visually look for a bonding clamp and conductor where the CSST enters the piping system, but confirming it's correctly sized and connected to an effective ground needs a licensed gas fitter or electrician.
Bonding requirements specifically target CSST because of its thin wall. Rigid black iron piping doesn't carry the same bonding requirement, though overall electrical grounding of the home still matters.
In practice it sits between the two trades. The gas fitter installing CSST should ensure bonding is done as part of a compliant install, coordinating with an electrician for the tie-in point if needed.
Unbonded CSST doesn't fail under normal daily use, but it loses the protection bonding provides against arcing from lightning-related or stray electrical energy, which is the specific risk the code requirement addresses.
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