What are the letters of fireproof twisted pair?

　　The identification letters of fireproof twisted pair mainly depend on the fireproof standards or certification system it meets. CoMMon identification methods are as follows:

　　1. International standards (such as UL certification)

　　CMP/CMR/CM：

　　CMP (Plenum): Highest flame retardant rating, suitable for ventilation ducts or air handling spaces.

　　CMR (Riser): suitable for shaft or vertical wiring.

　　CM (General Purpose): Ordinary flame retardant grade, suitable for general use.

　　For example, a twisted pair marked "CMP" meets the highest fire protection requirements.

　　LSZH/LSOH：

　　It indicates low SMoke, halogen-free flame retardant, low smoke and low toxicity when burning, and is commonly found in European standards (e.g. IEC 60332).

　　2. Domestic standards (e.g. Chinese GB standards)

　　ZR: Flame retardant grade label, commonly found in power cables, some communication cables may also be used.

　　FR: Some manufacturers may use "FR" to directly label flame retardancy.

　　3. Other signs

　　FTP/SFTP: shielded twisted pair (unrelated to fire protection, but may be present simultaneously).

　　NH: Fire-resistant cable (for power cables, less common for communication cables).

　　summarize

　　Generic letters: CMP, CMR, CM (UL flame retardant grade) or LSZH (low smoke halogen free).

　　Domestic common: ZR, FR.

　　Note: The specific marking needs to be combined with product certification (such as UL, CE) or manufacturer's instructions, and different standards may coexist. It is recommended to directly check the complete marking or specification sheet on the cable jacket to confirm.