Dry-type transformer seismic qualification and project anchorage are separate evidence checks. Qualification must cover the offered transformer and mounting configuration at the required seismic demand. The project also needs an accepted design for supports, attachments and the load path into the building. A seismic certificate alone does not approve the complete installation, and a strong foundation alone does not establish the transformer's post-earthquake functionality.
This guide helps U.S. engineers and procurement teams define the document handover before accepting a dry-type transformer proposal. It is a procurement checklist, not a structural calculation, installation procedure or statement that every U.S. project needs special seismic certification.
Start with the project's seismic requirement
Ask the responsible design professional to identify the governing code edition, jurisdiction and required performance before requesting a certificate. Record the equipment's intended function, installation level and mounting arrangement. Keep the requirement for equipment qualification separate from the requirement for restraint and anchorage.
California healthcare projects provide a useful, bounded example. HCAI's special seismic certification preapproval program, known as OSP, is a voluntary manufacturer preapproval route for qualifying nonstructural components used in healthcare construction. It is not a general national transformer approval or a requirement that every building use OSP-listed equipment.
The engineer should also identify any required product standards, electrical listing and efficiency documentation in separate specification rows. Keep each approval attached to the requirement it actually addresses.
Dry-type transformer seismic qualification: what does it establish?
Equipment qualification provides evidence for a defined design, configuration and seismic demand. Where special seismic certification is required, review the prescribed evidence for structural integrity and functionality, including the applicable test or certification basis. Do not translate a brochure phrase such as “seismic rated” into a universal performance guarantee.
The current HCAI OSP policy notice, revised October 23, 2025, describes shake-table testing under ICC-ES AC156 or an equivalent approved criterion. For the active or energized equipment covered by its cited CBC provision, it requires approved shake-table tests. That is a scoped California healthcare requirement, not a rule to apply indiscriminately to other jurisdictions.
Read the complete certification package, including model tables and installation limitations. A published dry-type transformer qualification record illustrates why: its tables distinguish construction, winding material, enclosure, dimensions, weight, mounting and seismic limits. Those details describe that record's covered equipment; they do not establish HEAKOR product capability.
What still needs an anchorage review?
The project must establish how seismic loads pass from the transformer through its supports and attachments into the supporting structure. The supporting floor, foundation or frame is part of that review. Equipment qualification cannot compensate for an unsuitable building connection.
A manufacturer's transformer mounting guidance distinguishes equipment qualification from the engineer's responsibility for project connection and anchorage details. HCAI's current OSP policy is similarly explicit: an approved OSP does not certify supports and attachments; the registered design professional supplies the required details and calculations.
For procurement, request a clear scope split. Identify who supplies the transformer mounting information, who designs the project supports and anchors, who coordinates the building interface, and who verifies installation against the approved documents. This guide does not select anchor types, bolt sizes, embedment, torque or reinforcement.
Match the evidence to the offered configuration
Use a revision-controlled comparison, not a certificate checkbox. The following is a suggested buyer checklist rather than a prescribed code form. Add a document reference, reviewer, open issue and disposition to each row.
| Review item | Information to compare | Procurement question |
|---|---|---|
| Project basis | Jurisdiction, governing code and standard editions, required function and acceptance route | Has the engineer issued the requirement bidders must answer? |
| Equipment identity | Offered model, drawing revision, phase, kVA, voltages and frequency | Which exact configuration is covered by the submitted evidence? |
| Physical construction | Enclosure, dimensions, operating weight, winding construction and relevant accessories | Are departures from the qualified assembly identified? |
| Mounting arrangement | Base, wall or suspended mounting; support and isolation arrangement | Does the proposed arrangement match the evidence limitations? |
| Seismic demand | Engineer-issued demand and qualification parameters, with their code basis | Has the responsible engineer accepted the demand-to-capacity comparison? |
| Project connection | Equipment attachment interface and approved support/anchorage documents | Who owns each part of the load path? |
| Evidence status | Report or approval identifier, revision, validity and covered configuration | Is the record applicable to this project and current offered design? |
| Release record | Accepted deviations, final drawings, required labels and inspection handover | What remains open before release or installation acceptance? |
Do not treat an untested model as covered simply because its kVA falls between two tested ratings. Require the supplier to identify the documented coverage basis and have the designated reviewer accept it. Likewise, record a bracket, enclosure or accessory substitution as a change for review instead of silently retaining the previous approval status.
Why a single seismic number is insufficient
The engineer must compare the applicable demand and qualification basis, rather than only the largest number on a certificate. SDS is the design spectral response acceleration parameter at short periods. Qualification documents may also identify installation height ratio z/h, component importance and other parameters or spectral acceleration limits.
HCAI's 2025 CBC preapproval update explains changes associated with ASCE 7-22, including height amplification and structure ductility factors. It specifically cautions against comparing only the preapproval SDS with the project's SDS.
Ask for a signed-off compatibility statement using the project's governing basis. Procurement should not convert an older certificate into a newer-code claim or calculate equivalence from catalogue values. A code-edition difference is a review item, not an automatic pass or rejection.
Close document gaps before technical release
A useful release record names the unresolved condition and the person authorized to close it. For example, if the final transformer weight is pending, record that dependency beside the support-design review. If an acoustic isolation option is proposed, flag the changed mounting arrangement before accepting the option.
- Issue one requirement set. Send the same project basis and document revisions to each bidder.
- Request an evidence index. Ask for the offered model's qualification references, drawings, limitations and deviations, with availability confirmed.
- Assign the interfaces. Separate equipment supply, structural design, installation and acceptance responsibilities.
- Resolve exceptions explicitly. Keep unsupported or mismatched claims open until the responsible engineer accepts a documented resolution.
- Preserve the accepted configuration. Route later substitutions through change review and update the release record.
Use the transformer RFQ checklist for the wider electrical and commercial enquiry. This seismic review adds a focused evidence requirement rather than replacing the full transformer specification.
Frequently asked questions
Does an electrical safety listing prove seismic qualification?
No. Check the stated scope of each record separately. Request the seismic evidence identified by the project specification rather than inferring it from an electrical listing mark.
Can a floor-mounted qualification cover a wall-mounted unit?
Do not assume so. Ask for evidence covering the proposed mounting orientation and configuration, and obtain the responsible engineer's acceptance before treating the proposal as compliant.
Should vibration-isolation pads be treated as a minor option?
No. Flag the actual isolation arrangement for review against the qualification and support design. Acoustic requirements and seismic requirements need coordinated decisions; procurement should not choose an isolation detail independently.
Is an older test automatically unusable on a newer-code project?
No. HCAI's 2025 preapproval guidance allows continued use of certain existing evidence subject to its conditions and the project-demand comparison. For any project, obtain the applicable authority's and engineer's acceptance rather than assuming either universal validity or automatic expiration.
Does absence from an OSP list settle whether a transformer can be used?
No. HCAI describes a project-specific approval route in its special seismic certification FAQs. Some FAQ examples refer to older CBC editions, so confirm the current project submittal requirements with the responsible design professional and HCAI. Other jurisdictions have their own acceptance basis.
Include the seismic requirement in your HEAKOR enquiry
Start from HEAKOR's dry-type transformer project information. For a U.S. enquiry, include phase, kVA, primary and secondary voltages, 60 Hz duty where specified, enclosure, installation location, mounting concept, quantity and schedule. Attach the engineer-issued seismic requirement and list the qualification and anchorage-interface documents requested.
Submit your project specification for review of the proposed equipment and available documentation. Any required seismic qualification must be confirmed for the exact design; this guide makes no HEAKOR seismic certification or project-approval claim. Final equipment acceptance and anchorage design remain subject to the responsible engineer and applicable authority.