Cracking is one of common quality issues of Low-Smoke Halogen-Free Flame（LSHF） Retardant Sheath. How to conduct effective testing and quality control over raw material of sheath before cable production is a challenge for many manufacturers. We tested the performance of raw material of cracked LSHF Flame Retardant Sheath together with raw material of normal LSHF Flame Retardant Sheath. The testing results show that the value of elongation at break of cracked LSHF Flame Retardant Sheath is much lower than that of normal LSHF Flame Retardant Sheath. In addition

the raw material of cracked LSHF Flame Retardant Sheath failed to pass the testing on thermal stress-cracking resistance. It is indicated that elongation at break and thermal stress-cracking resistance can serve as two key testing items before production of cable.