34.07° N · 118.10° W · WESTERN SGV
Seismic gas shutoff valves
An earthquake gas shutoff valve closes on its own in strong shaking.
Updated · 3 min read
Straight answer
A seismic gas shutoff valve closes your gas supply when shaking reaches a set level. SoCalGas says it must be installed on the house line, after the meter. After it trips, the valve is reset and appliances checked before pilots are relit.
What the valve does
Inside is a steel ball or a pendulum that drops into place during strong shaking, blocking the gas flow. It is a mechanical valve with no power required.
Its purpose is to keep gas from feeding a fire if a line breaks during a quake.
Where it goes
SoCalGas's earthquake valve page says the valve must be installed on your house line, not on the utility's meter set.
It also notes that only SoCalGas or its contractors may operate the service shutoff valve at the meter, so installation is often arranged around a service shutoff and restore.
After it trips
Do not reset the valve until you are sure there is no leak. SoCalGas recommends having the utility or a qualified professional check appliances and relight pilots.
If the valve trips without a quake, it may be mounted where it can be bumped, or not level. Reinstalling it correctly fixes false trips.
Is it required?
SoCalGas notes that some owners need one because of insurance or local building department rules. Requirements differ by city and by type of work, so check with your city or insurer.
FAQs
Can a seismic valve trip from a truck passing by?
Properly mounted valves are rated to ignore ordinary vibration. Frequent trips point to installation issues.
Do I still need to know how to shut off gas manually?
Yes. SoCalGas advises keeping a wrench available for the meter shutoff.
Will the valve work during a power outage?
Yes. It is purely mechanical.
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