本标准的目的是规定在规定条件下评估垂直安装的成束电线或电缆（电气或光学）垂直火焰蔓延的试验方法。本标准规定了B类，并与安装在试验梯架上的电缆有关，以使非金属材料的标称总体积达到3.5 l/m的试样。该类别适用于需要评估中等体积非金属材料的一般用途。

The objective of this Standard is to specify method of test for the assessment of vertical flame spread of vertically-mounted bunched wires or cables, electrical or optical, under defined conditions. This Standard specifies Category B and relates to cables installed on the test ladder to achieve a nominal total volume of non-metallic material of 3,5 l/m of test sample. The category is intended for general use where medium volumes on non-metallic material are required to be evaluated.