根据 GB 29415—2013《耐火电缆槽盒》，电缆桥架耐火时间分为 4 个等级：

According to GB 29415-2013 "Fire resistant Cable Tray Boxes", the fire resistance time of cable trays is divided into four levels:

F1：大于等于 90 分钟。

F1： Greater than or equal to 90 minutes.

F2：大于等于 60 分钟。

F2： Greater than or equal to 60 minutes.

F3：大于等于 45 分钟。

F3： Greater than or equal to 45 minutes.

F4：大于等于 30 分钟。

F4： Greater than or equal to 30 minutes.

另外，也有资料将电缆桥架的耐火等级分为 NI、NII、NIII 三个等级，其中 NI 等级耐火时间大于等于 60 分钟，NII 等级大于等于 45 分钟，NIII 等级大于等于 30 分钟。

In addition, there are also materials that classify the fire resistance level of cable trays into three levels: NI, NII, and NIII. Among them, the fire resistance time of NI level is greater than or equal to 60 minutes, NII level is greater than or equal to 45 minutes, and NIII level is greater than or equal to 30 minutes.

不同使用环境对防火桥架的耐火时间要求有所不同，如地下车库等对防火有特别要求的地段，防火桥架耐火时间要求大于 1 小时。在实际应用中，应根据具体的工程需求和相关规范来选择合适耐火时间的电缆桥架。

The fire resistance time requirements for fire-resistant cable trays vary depending on the usage environment. For example, in underground garages and other areas with special fire protection requirements, the fire resistance time of fire-resistant cable trays should be greater than 1 hour. In practical applications, cable trays with appropriate fire resistance time should be selected based on specific engineering requirements and relevant specifications.