How to clearly distinguish the flame retardant grade of wire and cable?

Do wire and cable industry people are very familiar with ZR, most of the wire and cable specifications before there is a ZR or ZA, ZB, ZC and so on the word, so, the specific flame retardant in the end what does it mean? The following cable manufacturers to explain briefly, what is the flame retardant grade of wire and cable, wire and cable flame retardant grade is how to grade.

ZR means flame retardant, flame retardant is divided into A, B, C three, ZB represents B flame retardant, ZR default is C flame retardant. Flame retardant properties ZA>ZB>ZC. Whether it is home installation wire or power cable will have the distinction of flame retardant grade. Flame retardant cable Class ABC is classified according to GB/T18380-2008 standard. It is used to evaluate the ability of vertically mounted bundle of wire cables or optical cables to inhibit the vertical spread of flame under specified conditions.

Flame retardant Class A refers to: the cable is installed on the test steel ladder to make the total volume of the test contains non-metallic materials for 7L/m, fire time for 40 minutes, after the cable combustion stop, dry the sample, the sample larger carbonization range shall not be higher than the bottom of the torch 2.5m.

Flame retardant B refers to: the cable is installed on the test steel ladder to make the total volume of non-metallic materials contained in the test is 3.5L/m, the fire time is 40 minutes, after the cable combustion stops, dry the sample, the sample larger carbonization range shall not be higher than the bottom of the torch 2.5m

Flame retardant C refers to: the cable is installed on the test steel ladder to make the total volume of non-metallic materials contained in the test is 1.5L/m, the fire time is 20 minutes, after the cable combustion stops, dry the sample, the sample larger carbonization range shall not be higher than the bottom of the torch 2.5m.