Screening of plenum cables using a small‐scale fire test protocol

The extent of flame propagation of electric cables in the FM Global intermediate‐scale parallel panel test (PPT) using a 60 kW sand burner has been correlated with a dimensional fire propagation index (FPI,)[(m/s^1/2)/(kW/m)^2/3] derived from ignition and vertical propagation tests in small‐scale ASTM E‐2058 Fire Propagation Apparatus (FPA). Two distinct types of fire behavior were observed in the PPT. The cables that did not propagate beyond the vicinity of the ignition burner flames have a FPI equal to or less than 7 [(m/s^1/2)/(kW/m)^2/3], whereas cables that propagated to the top of the 4.9 m parallel panels had a FPI equal to or greater than 14 [(m/s^1/2)/(kW/m)^2/3]. All the plenum rated (Ul‐910 or NFPA 262 tested) cables tested in this study did not exhibit flame propagation in the PPT, had FPI values of 7 [(m/s^1/2)/(kW/m)^2/3] or less and generated considerably lower smoke than those cables that propagated in the PPT. Based on this study, it is suggested that FPI measured in ASTM E‐2058 FPA may be used for screening cables for UL‐910 or NFPA262 tests, thus requiring substantially less cable to be supplied for testing. Copyright © 2005 John Wiley & Sons, Ltd.