How the TIA-942-A standard addresses plenum cable

The final point of debate in the standards group was whether or not to include a clause that instructed users to consult the AHJ about the use of plenum cable under access floors. So what did they decide?

In the fall we told you about a clause related to plenum cable that had become a point of debate within the development of the TIA-942-A Telecommunications Infrastructure Standard for Data Centers. The clause became the final hurdle the TR-42.1 Committee jumped before completing the standard earlier this month.

We described the situation in October 2011 as follows: As the 942-A standard was being developed, somewhere along the line a clause was included, stating that in some jurisdictions plenum-rated cable is the minimum requirement for telecom cabling being placed under access floors in computer rooms. The clause included the instruction to consult the authority-having-jurisdiction (AHJ) before placing cable in such an access-floor space. As the standard moved through the balloting process, a proposal was made to remove the clause. Now there is opposition to removing it.

As the debate went on, two primary stances emerged. Some believed the original text encouraged the use of plenum-rated cables and needed to be edited to remove such bias. Others believed the original guidance was an important consideration that should be factored into the decision regarding cable types in data centers.

In a testament to the fact that TIA develops standards on a consensus basis, TIA-942-A co-editor Jonathan Jew noted, "In the end we came up with language that was suitable for everyone."

That language is as follows:

Cable fire-rating requirements vary by installation conditions and jurisdiction. Consult the AHJ before deciding on the type of cable to use under access floors.

NOTE - Consider the selection of cable types (e.g. plenum-rated) and fire suppression practices that minimize damage to equipment and the facility in the event of a fire.

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