Appendix L — EARTHQUAKE RECORDING INSTRUMENTATION
L101 General — 2025 California Building Code
California Building Code (Title 24, Part 2) · 2025 edition · updated 2026-10-19 · California
CBSC: official editions, supplements and errata
Italicized text is a California amendment to the model code, as printed in the official publication.
Cite as: 2025 California Building Code (Title 24, Part 2) § L101 · Effective January 1, 2026 · Official source: Building Standards Commission
L101.1 General.¶
Every structure located where the 1-second spectral response acceleration, S 1, determined in accordance with Chapter 11 of ASCE 7, is greater than 0.40 and either exceeds six stories in height with an aggregate floor area of 60,000 square feet (5574 m [2] ) or more, or exceeds 10 stories in height regardless of floor area, shall be equipped with not fewer than three approved recording accelerographs. The accelerographs shall be interconnected for common start and common timing.
[OSHPD 1 & 4] There shall be a sufficient number of instruments to characterize the response of the building during an earthquake and shall include at least one tri-axial free field instrument or equivalent.
L101.2 Location.¶
As a minimum, instruments shall be located at the lowest level, mid-height, and near the top of the structure. Each instrument shall be located so that access is maintained at all times and is unobstructed by room contents. A sign stating “MAINTAIN CLEAR ACCESS TO THIS INSTRUMENT” in 1-inch (25 mm) block letters shall be posted in a conspicuous location.
[OSHPD 1 & 4] A proposal for instrumentation and equipment specifications shall be forwarded to the enforcement agency for review and approval.
L101.3 Maintenance.¶
Maintenance and service of the instrumentation shall be provided by the owner of the structure. Data produced by the instrument shall be made available to the building official on request.
Maintenance and service of the instruments shall be performed annually by an approved testing agency. The owner shall file with the building official a written report from an approved testing agency certifying that each instrument has been serviced and is in proper working condition. This report shall be submitted when the instruments are installed and annually thereafter. Each instrument shall have affixed to it an externally visible tag specifying the date of the last maintenance or service and the printed name and address of the testing agency.
[OSHPD 1] Data retrieval from the instrument and processing of the records shall be the responsibility of the enforcement agency.
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