OSHPD Generator Seismic Certification
Emergency and standby gensets serving California hospitals are Iₚ = 1.5 by default — they must run after the Design Earthquake. That means AC156 shake-table qualification, an OSP pre-approval or project-specific certification, and a properly engineered isolator + snubber base.
Four certification paths for generators
Because every hospital genset is Iₚ = 1.5, analysis-only certification is not allowed. The genset must be qualified by AC156 shake-table testing — either through a reusable OSP listing, or as a one-time project package paired with a tested isolator family.
OSP pre-approval
For genset OEMs and packagers selling the same model into California hospitals. One AC156 test program, reusable across every project.
Learn more about OSP pre-approvalAC156 shake table testing
Mandatory for Ip = 1.5 generators. Includes engine, alternator, controls, and the isolator/snubber base — all tested as one assembly.
Learn more about AC156 shake table testingVibration isolation & snubbers
Engineered isolator + snubber selection sized for the genset's operating weight, CG height, and SDS at the project site.
Learn more about Vibration isolation & snubbersProject anchorage letter
PE/SE-stamped calc package for a specific genset on a specific pad when OSP isn't justified.
Learn more about Project anchorage letterWhy isolator selection matters for generator OSP
The OSP applies to the tested assembly — engine, alternator, controls, and the specific isolator/snubber base used during AC156. Swap the isolator on the project and the OSP no longer covers the install.
If the spec'd isolator isn't covered by the genset OSP envelope or a separate OPM, you're either re-testing or producing a project-specific certification package. We help packagers map the OSP envelope to commonly spec'd isolator families to avoid this trap.
What we need to scope a generator cert
- Genset cut-sheet, dry/wet operating weight, and CG height
- Mounting: rigid skid, spring isolators, or housed restrained isolators
- Existing OSP/OPM number (if certifying a substitution)
- SDS at the project site (from geotech / structural engineer)
- Hospital project number and HCAI office (Northern / Southern CA)
- Sub-base fuel tank — included in the assembly or anchored separately?
Quote a generator cert in 24 hours
Send us the genset cut-sheet, weight, isolator model, and Ip designation. You'll have a scoped, itemized PE/SE-stamped proposal — typically within one business day.
PE/SE stamped • Hundreds of California hospital projects since 2008
Frequently asked questions
- Do emergency generators need OSHPD seismic certification?
- Yes. Emergency and standby generators serving California hospitals are designated Ip = 1.5 under ASCE 7-22 §13.1.3 because they must operate post-earthquake to power life-safety branches. They require either OSP pre-approval with AC156 shake-table testing, or a project-specific certification package — anchorage-only is never sufficient for an active genset.
- Can I swap vibration isolators on an OSHPD-certified generator?
- No — not without re-certification. The isolator and snubber assembly is part of what was tested under AC156. Substituting a different isolator changes the system dynamics and voids the OSP. The replacement isolator must be either covered by the original OSP envelope, listed under a separate OPM, or re-tested.
- What's the typical lead time for a generator OSP?
- Plan for 4-9 months end-to-end: 4-8 weeks for AC156 test scheduling and execution, 60 days HCAI first review, then 30-day backcheck cycles. A project-specific anchorage letter for a one-off install is much faster — typically 2-4 weeks.