Cable tests that are not equivalent, and why
IEC 61034-2 ≠ UL 1685 ST1 / LS
Not equivalent, because UL 1685 measures the smoke of the tray fire itself; IEC 61034-2 burns a sample in a closed 3 m cube and measures how much light still gets through.
IEC 61034-2
- A sample burnt in a closed 3 m cube; the smoke is measured as the light that still gets through. Sources: IEC 61034-1 and IEC 61034-2:2005+AMD1:2013+AMD2:2019 (edition 3.2): 61034-1 cl 4 p. 6 (3 m cube); 61034-2 Annex B p. 17 (recommended light transmittance), cl 7 p. 9 (normalisation) (read in the standard)
- IEC 61034-2 itself recommends at least 60 % light transmittance where the cable standard sets no limit. Sources: IEC 61034-1 and IEC 61034-2:2005+AMD1:2013+AMD2:2019 (edition 3.2): 61034-1 cl 4 p. 6 (3 m cube); 61034-2 Annex B p. 17 (recommended light transmittance), cl 7 p. 9 (normalisation) (read in the standard)
- The limit is the product standard's, for example BS 6724: light transmittance at least 70 %. Sources: BS 6724:1997+A3:2008, Table 2, p. 10 (read in the standard)
- CPR s1a: at least 80 %; s1b: 60 % to under 80 %. Sources: EN 13501-6 draft (BSI FSH/21_11_0073, undated, before the published EN 13501-6:2014), Table 1 notes (2) to (7), p. 21 (read in a draft)
UL 1685 ST1 / LS
- Smoke measured in the tray fire: total smoke at most 95 m², peak rate at most 0.25 m²/s. Sources: M. Hirschler, FAA Fire and Materials conference 2001, slides (quoted by others); VTEC Laboratories, cable fire tests (quoted by others)
Values as the sources print them, every one with its source and how it was seen; where a value is not held, it says so. The cable's own standard and the specification decide which test applies.
Questions and answers
Is UL 1685 ST1 / LS equivalent to IEC 61034-2?
No. UL 1685 measures the smoke of the tray fire itself; IEC 61034-2 burns a sample in a closed 3 m cube and measures how much light still gets through.