Seismic Gas Shut-Off Valves

Common questions

What does a seismic gas valve actually do?

It sits on your gas line just downstream of the meter and closes automatically when it senses shaking above a set threshold. The point is to stop gas feeding a leak or a fire in the minutes after a quake, when nobody is going to be outside turning the meter off by hand.

Am I required to have one?

It depends on your jurisdiction and the work being done. Some California cities require one on new construction, major remodels, or at point of sale — the rules vary by city, so it's worth checking yours. Plenty of people install one without being required to, simply because of where we live.

What happens after an earthquake — does it reset itself?

No, and that's deliberate. It stays closed until someone resets it manually, so gas isn't restored to a house that may have damaged lines inside. Resetting is straightforward, but the system should be checked before the gas goes back on.

Will it trip every time there's a small quake?

It shouldn't. These are calibrated to actuate at a shaking intensity associated with potential structural damage, not at every tremor you can feel.

Can I fit one myself?

Please don't. It's gas work on the supply side of the meter, it needs correct sizing for your load, and it needs a permit and inspection. Getting it wrong on a gas line is not a DIY-recoverable mistake.