Fire-resistant cable models typically use a combination of letters to indicate their characteristics, primarily including flame retardant, fire-resistant, and low-smoke halogen-free. The following is a detailed explanation of common letter specifications:
1. Flame-retardant Cable (ZR Series)
ZR is a general designation for flame retardancy, indicating that the cable has the ability to prevent the spread of fire. Common models include ZR-YJV (flame-retardant cross-linked polyethylene insulated cable) and ZR-VV (flame-retardant polyvinyl chloride insulated cable).
Flame retardancy grades are further divided into ZA, ZB, ZC, and ZD, corresponding to grades A, B, C, and D (grade A being the highest). For example, ZA-VV indicates a grade A flame-retardant polyvinyl chloride cable.
2. Fire-resistant Cable (NH Series)
NH stands for fire resistance, indicating the ability to maintain line integrity during a fire, such as NH-YJV (fire-resistant cross-linked polyethylene cable).
Higher-standard fire-resistant cable models include BTTZ (copper core, copper sheathed, magnesium oxide mineral insulated cable, resistant to temperatures up to 1000°C) and YTTW (flexible fire-resistant metal sheathed mineral insulated cable).
3. Low-smoke, halogen-free cable (WDZ series)
WDZ stands for halogen-free, low-smoke, flame-retardant cable, such as WDZ-YJV (halogen-free, low-smoke, flame-retardant cross-linked polyethylene cable).
These cables produce low smoke concentrations and release no toxic halogen gases when burned, meeting environmental requirements.
4. Other special fire-resistant models
BTTRZ/RTTZ: Flexible mineral insulated fire-resistant cable with improved bending properties.
NG-A (BTLY): Aluminum sheathed, flexible, isolated fire-resistant cable, combining electrical conductivity and fire resistance.
BBTRZ: Flexible magnesium hydroxide mineral insulated cable, fire-resistant and with a high current carrying capacity.
