Document BRk2wwgRJLL9oj50gkO5bQOBX

MEMO 10: J. P. S. Abbott FROM: Pi. E. King April 9, 1959 cc: Messrs: A. S, Basil J. F, McClelland E E. Barth (2) K. D. Barker 0. S. Buettner file (2) SUBJECT: BP 554 - Flame Test Performance of Silicone Rubber Asbestos Braided Power Cables In the course of naming tests on samples of early production cable of this oetagory, it was discovered by S & D that flame test performance to the Underwriters* Vertical Flame Test requirement was not all it should bo, with approximately l/S of the material failing to meet the requirement. Further testing was conducted, and an evaluation of various means of preventing the failures was made* During the investigation 61 specimens of regular production material and specimens braided with the same coverage (64$) as regular production material were tested, with 23 failures reported. Higher coverages of approximately 67$ and 75$ showed significant improvement with zero failures in SO tests at 75$ and 4 failures in 58 tests at 67$ coverage. In view of the above experience, in order to obtain equivalent flame test performance of the #14 cable to the other sizes in the line, I requested a change in specification to 67*7$ braid coverage which was written up on March 19, 1959. rs. R. E, King RBB 00715 SC-ELEC-03115