A common misconception is that flame-retardant means the cable will not burn. The purpose is to slow fire spread, not eliminate fire completely. Technically, PVC and PE can. Indoor cables focus on flame resistance and flexibility inside buildings. Choosing the wrong type exposes your network to microbending, water ingress, tensile failure, and premature aging. This short guide explains the commonly used materials — LSZH and PVC — how industry fire-rating systems (plenum, riser, vertical flame tests) work, and practical tradeoffs so you. The use of green or low-smoke alternatives to the halogen-free (LSZH) cables. Emits minimal smoke, no halogens, is highly flame-resistant, environmentally safe, and most. Fire ratings are classification systems used to define how communication cables behave when exposed to fire conditions.