| Full title | ANSI/TIA-942, Telecommunications Infrastructure Standard for Data Centers |
| Publisher | Telecommunications Industry Association (TIA), committee TR-42.1 |
| Current revision | ANSI/TIA-942-C, approved February 2024 and published May 2024 |
| Status | Current. An addendum related to AI data centres is listed as new work (TR-42, October 2025) |
| Previous revisions | TIA-942 (2005), 942-A (2012), 942-B with Addendum 942-B-1 on edge data centres |
| Related standards | ISO/IEC 11801-5, EN 50173-5, ANSI/TIA-568 series, ANSI/TIA-606 |
What it covers
ANSI/TIA-942 specifies minimum requirements for data centre infrastructure. The core is telecommunications cabling, spaces and topology. It also covers site location, architecture, electrical, mechanical, fire safety, physical security and monitoring, and gives a system of resilience ratings.
ISO/IEC 11801-5 and EN 50173-5 deal with the cabling only.
Data centre spaces
The cabling follows a hierarchical star topology based on the TIA commercial building model.
| Space | Full name | Role |
|---|---|---|
| ER | Entrance room | Access provider equipment and demarcation points; interface with campus cabling. Recommended to be outside the computer room for security |
| MDA | Main distribution area | Main cross-connect and core routers and switches. At least one is required |
| IDA | Intermediate distribution area | Intermediate cross-connect for large data centres, between the MDA and HDAs |
| HDA | Horizontal distribution area | Horizontal cross-connect and the equipment that serves the equipment distribution areas |
| ZDA | Zone distribution area | Optional interconnection point in horizontal cabling between the HDA and EDA. No cross-connects or active equipment |
| EDA | Equipment distribution area | Equipment cabinets and racks where horizontal cabling terminates |
In small data centres some of these functions can be combined, for example the MDA and HDA in one space.
Rated levels
| Level | Description |
|---|---|
| Rated-1 | Basic site infrastructure |
| Rated-2 | Redundant component site infrastructure |
| Rated-3 | Concurrently maintainable site infrastructure |
| Rated-4 | Fault tolerant site infrastructure |
In 942-C the annex on infrastructure rating is normative, but any rating system may be used. The rating tables in Annex D are normative where the TIA-942 rating system is used. TIA ratings are separate from the Uptime Institute Tier scheme.
What changed in 942-C
- Incorporates Addendum 942-B-1 on edge data centres, with an annex on micro edge data centre types
- Recognises single balanced twisted-pair cable for horizontal cabling
- Allows any optical fibre connector that meets ANSI/TIA-568.3, except at the equipment outlet, where LC and MPO connectors are still required
- Where balanced twisted-pair cabling is used for wireless access points, requires at least two Category 6A or higher cabling runs to each one
- Requires cabinets in the MDA, IDA and HDA to be at least 800 mm wide
- Sets a minimum floor loading of 5 kPa for computer rooms under 20 m²
- Recommends at least two optical fibres for horizontal and backbone cabling
- Updates temperature and humidity references to the ASHRAE TC 9.9 recommended envelope, and adds an informative annex on immersion cooling
- Makes several annexes normative, including space considerations, site selection and building design
Earlier changes still relevant
942-A (2012) added the intermediate distribution area, removed the 100 m length limit for optical fibre horizontal cabling (length is set by the application), and aligned connectors with international standards: LC for one or two fibres and MPO for more than two.
How it relates to other standards
TIA-942 defines data centre spaces, while ISO/IEC 11801-5 and EN 50173-5 define functional elements. Component and test performance in TIA-942 comes from ANSI/TIA-568.2 (twisted-pair) and ANSI/TIA-568.3 (optical fibre). Labelling follows ANSI/TIA-606.
What it means in practice
- On UK and European projects, check which document is the contract standard.
- If a client asks for a Rated level, confirm whether they mean TIA-942 ratings or another scheme.
- Plan cabinet widths of 800 mm or more in distribution areas to leave room for cable management.
- Provide LC or MPO connectivity at the equipment outlet in the EDA.
- Where balanced twisted-pair cabling is used for wireless access points, allow at least two Category 6A cabling runs to each one.
Related reading: Fibre optic connectors explained: LC vs SC · OM4 vs OM5 fibre: what’s the difference?.