How to Choose an IT Rack

Overview

The guide covers rack forms (two-post, four-post, cabinet), components and accessories, and the criteria that matter: dimensions, serviceability features, structural load ratings, material and finish. It sets out the 19-inch/U conventions: 1U is 44.45 mm, a 42U rack offers about 1.87 m of interior mounting height, and standard equipment width is 482.6 mm per EIA-310-D / IEC 60297-3-100. A five-step selection process ties equipment attributes, growth plan and density to rack size and weight capacity, and an appendix describes the UL 2416 test methods and ISTA 3E transport testing.

The long-standard 600 x 1070 mm 42U cabinet becomes cramped at 5 kW and above. Alternatives are 45U/48U/52U up to 60U tall, 750/800 mm wide and 1100/1200/1500 mm deep. Recommended footprints are 600 x 1200 mm for 1U servers, 600 x 1070 mm for mixed 2U/4U and network storage, 750 x 1070 mm for blade, high-density networking and converged systems, and 750 x 1200 mm for deep high-density networking. Racks should be no taller than the lowest door opening on the delivery path, and a 64% perforated door is reported not to impair cooling even at 30 kW/rack or higher.

Structural guidance centres on static and dynamic load ratings verified by third parties. Under the UL 2416 static option the cabinet must hold 4 times the published load; the published rating is the tested load reduced by 75%, a safety factor of 3, and the bonding test allows no more than 2 ohms and 2 V drop over 2 minutes. Fully populated cabinets generally rely on ISTA 3E transport testing. Racks typically last more than eight years and cost less than 5% of physical infrastructure capex; electrogalvanized steel is not recommended because of zinc whiskers.

Key points

1. 1U = 44.45 mm; 42U gives about 1.87 m interior height; standard width 482.6 mm (EIA-310-D / IEC 60297-3-100).
2. Most common rack: 600 mm wide, 1070 mm deep, 42U.
3. Recommended footprints: 600 x 1200 mm for 1U servers, 750 x 1070 mm for blade and converged systems.
4. Network racks 750 x 1070 mm; server racks 600 x 1200 mm.
5. A 64% perforated door does not impair cooling even at 30 kW/rack or higher.
6. UL 2416: cabinet holds 4x the published load; published rating is the tested load reduced by 75% (factor 3).
7. Fully populated shipments rely on ISTA 3E testing.
8. Racks last 8+ years and cost under 5% of physical infrastructure capex; avoid electrogalvanized steel.

Using it in design

• Add rack catalog fields: form, width, depth, height in U, static and dynamic load, UL 2416 and ISTA 3E flags, door perforation.
• Warn when rack height exceeds the smallest door or lift opening on the delivery route.
• Warn when equipment plus PDU weight exceeds the static rating; for pre-populated delivery require dynamic rating and ISTA 3E.
• Suggest 750 mm width for network/blade racks and 1200 mm depth for 1U server racks; flag electrogalvanized finish.

Who should read it

Design engineers and procurement teams specifying racks and cabinets.

Related standards

• EIA-310-D
• IEC 60297-3-100
• UL 2416
• ISTA 3E
• Telcordia GR-63-CORE

Publication details

Authors

Pearl Hu; Wei Zhou

Publisher

Schneider Electric

Year

2020

Document number

WP 201

Document language

English

Source type

Manufacturer

Access

Free to read

Licence

Copyright retained; citation only — the publisher’s terms apply to the original document

Citation