Case Study · AI Research

Three switchgear lineups up to 4000A for OpenAI

Built for Rosendin Electric, for OpenAI

Delivered Sep 2026 a six-figure order

Key facts

The build at a glance

3 switchgear lineups

Units

Low-voltage switchgear in switchboard construction

Product

4000A, 3000A and 1200A

Amperage

480Y/277V, 3-phase 4-wire

Voltage

Tin-plated aluminum

Bus

NEMA 1 (indoor)

Enclosure

65 kAIC

Interrupting rating

UL 891 low-voltage

Listing

Siemens WL insulated-case and 3VA molded-case

Breakers

About 13 weeks from order to shipment, June to September 2026

Turnaround

Jurupa Valley, California

Built in

01 · Challenge

The challenge

For OpenAI, Rosendin Electric needed three 480Y/277V distribution switchgear lineups, the largest at 4000A, built to the project’s submittal.

02 · Build

What DEI built

Three UL 891 low-voltage switchgear lineups in switchboard construction: 4000A, 3000A and 1200A, all at 480Y/277V three-phase four-wire, 65 kAIC, NEMA 1, with tin-plated aluminum bus. The 3000A lineup feeds four 1600A breakers with LSIG trip units and Dynamic Arc Flash Sentry; the 1200A lineup takes a 1000A main. Mains and feeders are Siemens WL insulated-case and 3VA molded-case breakers.

QtyItemRatingVoltageEnclosureBusNotes
1Switchgear lineup4000A480Y/277V 3Ø 4WNEMA 1Aluminum, tin-platedSiemens WL main; 65 kAIC; UL 891 low-voltage
1Switchgear lineup3000A480Y/277V 3Ø 4WNEMA 1Aluminum, tin-platedFour 1600A LSIG feeders with Dynamic Arc Flash Sentry; 65 kAIC
1Switchgear lineup1200A480Y/277V 3Ø 4WNEMA 1Aluminum, tin-plated1000A Siemens 3VA main; 65 kAIC

03 · Delivery

How DEI delivered

Jun 2026
Order
Done
Engineering
Aug 2026
Fabrication & bus bar
Sep 2026
Assembly
Sep 2026
QC
Sep 2026
Shipped

Engineered, fabricated and assembled under one roof in Jurupa Valley, California.

The order was placed in June 2026 and the three lineups shipped together in September 2026, about 13 weeks from order to shipment. DEI’s engineers revised the submittal drawings in July 2026; fabrication and bus bar work ran in August, assembly ran from August into September, and QC and shipment followed in September.

DEI’s facility in Jurupa Valley, California
Photographed at DEI’s shop, Jurupa Valley, California.

04 · Result

The result

Three switchgear lineups up to 4000A, engineered and built by DEI and shipped together in September 2026, about 13 weeks after the order.

05 · Specifications

Specifications, build by build

One order — three switchgear lineups

From DEI’s submittal, Jul 2026

QtyItemRatingVoltageEnclosureBusNotes
1Switchgear lineup4000A480Y/277V 3Ø 4WNEMA 1Aluminum, tin-platedSiemens WL main; 65 kAIC; UL 891 low-voltage
1Switchgear lineup3000A480Y/277V 3Ø 4WNEMA 1Aluminum, tin-platedFour 1600A LSIG feeders with Dynamic Arc Flash Sentry; 65 kAIC
1Switchgear lineup1200A480Y/277V 3Ø 4WNEMA 1Aluminum, tin-plated1000A Siemens 3VA main; 65 kAIC
  • UL 891 low-voltage switchgear in switchboard construction: 4000A, 3000A and 1200A lineups
  • 480Y/277V, 3-phase 4-wire; 65 kAIC; NEMA 1; tin-plated aluminum bus
  • 3000A lineup: four 1600A feeders, LSIG with Dynamic Arc Flash Sentry
  • 1200A lineup: 1000A 3-pole main (Siemens 3VA)
  • Siemens WL insulated-case and 3VA molded-case breakers throughout
  • Ordered June 2026; fabrication and bus bar August 2026; assembly August to September 2026; QC and shipment September 2026

06 · Related

Related case studies

Send us your one-line diagram — we'll tell you what we'd build, and when.

Company names identify who DEI’s orders are for. Their use does not imply endorsement of DEI.

Dates, quantities and turnarounds as of September 2026, from DEI’s build and order records. Images are representative unless marked otherwise.

About Us

Contact Us

Office Location

4725 Troy Ct.
Jurupa Valley CA 92509

Contact Info

Phone: +1 (866) 773-8050
Email: sales@deipower.com

The Importance of UL 891 Switchgear in Modern Facilities

The Future of Switchgear in Data Centers