Classification of Fire Rating Standards for Trough-Type Fireproof Cable Trays

Time：2025-04-20　 Browse：11　Text size：

The fire rating of trough-type fire-resistant cable trays is primarily defined by fire endurance—the duration for which structural integrity and electrical circuit continuity are maintained under standard fire exposure. In China, the authoritative governing standard is GB 29415-2013 Fire-Resistant Cable Trays.

1. National Standard Core Classification (F1–F4, Widely Used in Engineering)

Grade	Fire Resistance Duration	Typical Applications
F1	≥ 90 minutes	Super high-rise buildings, hospitals, data centers, subways, fire emergency main lines
F2	≥ 60 minutes	Main distribution lines in shopping malls, office buildings, hotels and general public buildings
F3	≥ 45 minutes	General industrial plants, multi-story residential buildings, general lighting and control circuits
F4	≥ 30 minutes	Small buildings, secondary circuits and auxiliary rooms

2. Other Common Classification Systems

JB/T 10216 three-level system (NⅠ–NⅢ)

NⅠ: ≥ 60 min

NⅡ: ≥ 45 min

NⅢ: ≥ 30 min
FH series (commonly used in engineering)

FH‑A: ≥ 120 min (highest grade)

FH‑B: ≥ 90 min

FH‑C: ≥ 60 min
Direct time notation: F30, F60, F90, F120 (directly representing fire resistance in minutes)

3. Key Test Criteria (GB 29415)

Test condition: Continuous heating in accordance with the standard time‑temperature curve (approx. 950℃).
- Structural integrity: No collapse, no through‑cracks, deflection ≤ L/100.
- Circuit integrity: Internal cable circuit remains uninterrupted (3A fuse does not blow).
- Thermal insulation: Average backside temperature rise ≤ 180℃, single‑point temperature rise ≤ 220℃.Evaluation indicators:

4. Key Points for Selection and Acceptance

Trough‑type fireproof cable trays shall be fully enclosed with covers and form a complete fireproof system together with fireproof sealing.
During acceptance, verify the type test report, which shall clearly state the F1/F2/F3/F4 grade and rated fire resistance duration.
The fire rating shall be matched with the fire performance of the cables (e.g., F1 cable trays used with NH fire‑resistant cables).

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