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At a recent meeting of the NFPA 2001 Technical Committee, Comment ROC 2001-61a (log #CC7) was proposed, and after much debate, the Committee voted to propose its inclusion in the next version of NFPA 2001. Comment ROC 2001-61a would require that the minimum design concentration for a Class C hazard be increased from the current level of 1.2 times the Class A minimum extinguishing concentration to 1.6 times the Class A minimum extinguishing concentration for scenarios in which the power dissipation from an electrical circuit failure is not likely to exceed 1500 W continuous. Higher concentrations would be required to be specied for scenarios in which the power dissipation from an electrical circuit failure exceeds 1500 W continuous.

In this paper we discuss the implications of ROC 2001-61a, and discuss in detail the tests which have been cited as justication for ROC 2001-61a. It is concluded that neither eld experience over the past 15 years, nor the cited tests justify the far-reaching changes that would result from the acceptance of ROC 2001-61a. The cited tests suer from numerous shortcomings, e.g., poor reproducibility, questionable relationship of test congurations to real world re scenarios, etc., and these shortcomings are discussed in detail.

Following this review of past eorts, we present the results of our recent suppression testing of clean agents on electrically energized components. These tests employ congurations believed to be representative of real world hazards, and avoid the shortcomings of the previously reported studies. There is currently no standard test method available for the evaluation of the performance of suppression agents on res involving electrically energized equipment, and it is anticipated that these tests can serve as the basis for the development of such a standard test method.

CLASS C FIRES INTRODUCTION Section of NFPA 10 Standard for Portable Fire Extinguishers denes Class C res as“Fires that involve energized electrical equipment.” Class C res are of concern due to the fact that in some applications power disconnection is highly undesirable due to the magnitude of the nancial impact associated with system downtime.

As discussed by Robin and McKenna1, service interruptions are a major concern in telecommunication facilities due to the unique nature of the information processing performed in such facilities. Telecommunication systems are on-line information exchange systems: the system does not store or process customer data, but merely transfers the data from one point to another. When a service disruption occurs, all information in transit is lost. This contrasts to the case of data processing centers, where data is stored in the systems memory, and during an interruption only that data which has not yet been placed in permanent memory (i.e., disks, tapes) is lost.
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