The Telecommunications Industry Association (TIA) Engineering Committee TR-42 Telecommunications Cabling Systems has approved the publication of TIA-942-A, the revised Telecommunications Infrastructure Standard for Data Centers. Several of the changes made from the original 942 standard have practical effects on the design, installation and management of structured cabling systems in data centers.
The revised standard was several years in development. In May 2010, Cabling Installation & Maintenancepublished this article authored by TIA-942-A co-editor Jonathan Jew, president of J&M Consultants. The article outlined the changes from the original TIA-942 standard that were anticipated to be included in TIA-942-A.
Recently, Jew summarized for us the changes in the new standard as follows.
Incorporate Addenda to TIA-942:
- Addendum 1 - Additional coaxial cabling specifications and revised distances
- Addendum 2 - General updates including revised tiering, the addition of Category 6A, 3-level lighting protocol, revised temperature and humidity limits
Restructuring Standards - Integrate into the TIA-568-C series:
- Reference generic cabling topology (horizontal = cabling subsystem 1, distributor C = MC, B = IC, A = HC), terms, and MICE (mechanical ingress, climatic, electromagnetic) environmental classifications
- Move bonding and grounding content to TIA-568-B
- Move administration content to TIA-606-B
- Move racks and cabinets, power and telecom separation, environmental requirements (temperature and humidity) to TIA-569-C and new addendum
- Move outside plant pathways to TIA-758-B
Harmonize with International Standards:
- Adopt the terms Equipment Outlet (EO) and External Network Interface (ENI - interface between external and internal networks in data center located in the entrance room)
- Standardize on LC for 1 or 2 fibers and MPO for more than 3 fibers on a single connector
- Remove distance limitation for horizontal cabling of optical fiber (based on application)
- Higher Bandwidth Applications
- Removed support for Category 3 and Category 5e for horizontal cabling, retained for backbone cabling for console connections, telephone/modem lines, WAN circuits
- Minimum requirement of Category 6 for horizontal cabling, recommendation is Category 6A (or higher)
- Removed support for OM1 and OM2; minimum requirement is OM3; recommendation is OM4
- Retained singlemode fiber and 734/735 coax
- New section on energy efficiency
- Wider range of temperature and humidity (see TIA-568-C) based on new ASHRAE TC 9.9 guidelines
- Use of enclosures or enclosure systems to improve energy efficiency (cabinets with isolated supply or return, cabinet cooling systems, hot or cold aisle containment, panels and cable management that reduce air bypass, brushes/grommets on floor tiles)
- 3-Level Lighting Protocol - lighting levels based on occupancy and function (1. Lighting levels are minimal when the space is not occupied - enough for video surveillance. 2. Initial entry - safe passage. 3. Occupied - 500 lux.)
- Recommend the use of energy efficient lighting such as LED
Larger and Modular Data Centers:
- New space, Intermediate Distribution Area (IDA), containing the Intermediate Crossconnect (IC)
- IDA also being adopted in ISO/IEC 24764 in new addendum, but will be called the Intermediate Distributor (ID)
- Elimination of requirement that centralized optical fiber technologies be limited to one building to accommodate modular data centers using outdoor containers/modules
Recently, Jonathan Jew and TIA's associate vice president of technology and standards, Herb Congdon, discussed 942-A in a video produced by TIA. Their discussion included some of the standard's implications for designers, installers and users of structured cabling systems. A still image from the video is at the bottom of this page.