| Full title | Tests on electric and optical fibre cables under fire conditions. Part 3: Test for vertical flame spread of vertically-mounted bunched wires or cables |
| Publisher | IEC (TC 20); adopted as EN IEC by CENELEC and as BS EN IEC by BSI |
| Current edition | IEC 60332-3-10 and 3-21 to 3-25:2018 (edition 2.0). BS EN IEC versions published in 2018 |
| Status | Current. Each part replaces its EN 60332-3-xx:2009 predecessor |
| CPR status | Not a CPR reaction to fire classification test |
| Related | EN 50399, EN 60332-1-2, EN 61034-2, BS 7671 Regulation 422.2.1 |
What it covers
The EN IEC 60332-3 series tests how far flame spreads up a vertical bunch of wires or cables, electrical or optical, under defined conditions. It exists because a single cable test such as EN 60332-1-2 cannot show how a bunch of the same cables will behave.
Flame spread along a bunch depends on things like the volume of combustible material, how the cables are arranged, the air flow and the cable construction. The series controls these by setting a volume of non-metallic material per metre of ladder, a mounting method and a flame application time.
The standard itself says the categories are not necessarily linked to different safety levels in real installations.
The parts
| Part | Category | Non-metallic volume | Flame time | Mounting and scope |
|---|---|---|---|---|
| 3-10 | Apparatus | Not applicable | Not applicable | Test chamber, ladders, burner and calibration |
| 3-21 | A F/R | 7 l/m | 40 min | Spaced, front and rear of ladder. Power cables over 35 mm² only. Special designs, not for general use |
| 3-22 | A | 7 l/m | 40 min | Front of ladder |
| 3-23 | B | 3.5 l/m | 40 min | Front of standard ladder |
| 3-24 | C | 1.5 l/m | 20 min | Front of standard ladder |
| 3-25 | D | 0.5 l/m | 20 min | Front of standard ladder, touching only. Cables up to 12 mm diameter and 35 mm² only |
The volume is the nominal total volume of non-metallic material (insulation, sheath, fillers) per metre of test sample. It sets how many 3.5 m lengths go on the ladder. In all categories, cables with at least one conductor over 35 mm² are tested spaced apart. Cables of 35 mm² and smaller, and optical fibre cables, are tested touching.
The test
| Item | Requirement |
|---|---|
| Test chamber | Vertical chamber about 1 m wide, 2 m deep and 4 m high |
| Ladder | Steel ladder, standard or wide, standing vertically in the chamber |
| Test pieces | 3.5 m lengths, fixed to the ladder to reach the category volume |
| Ignition source | Propane ribbon burner, mounted horizontally in front of the cables |
| Flame application | 40 min (categories A F/R, A, B) or 20 min (categories C, D) |
Recommended pass criterion (Annex B)
After burning has stopped, the cables are wiped clean and the charred or affected part is measured. The recommended requirement is that the charred or affected portion does not reach a height of more than 2.5 m above the bottom edge of the burner. Soot that wipes off, softening and deformation are ignored.
Changes in the 2018 editions
- Wording changed throughout to make clear that optical fibre cables are covered, not only metallic conductor cables.
- Mounting of cables on the ladder defined more precisely, to improve repeatability and reproducibility.
- The connection between the venturi mixer and the burner better defined (Part 3-10).
Relationship with EN 50399 and the CPR
EN IEC 60332-3 is not a CPR reaction to fire classification test. The CPR classes Aca to Fca in EN 13501-6 use only EN ISO 1716, EN 50399 and EN 60332-1-2. A 60332-3 category result cannot be converted into a CPR class.
EN 50399 uses a similar vertical ladder and chamber. Until its 2022 edition, EN 50399 referred to EN 60332-3-10 for the apparatus. The difference is in what is measured. EN 60332-3 records only the charred height. EN 50399 also measures heat release, smoke production and flaming droplets, which the CPR classes need.
BS 7671 and escape routes
BS 7671 Regulation 422.2.1 (in the form introduced by A2:2022) covers cables in protected escape routes. Cables installed there must have resistance to flame propagation meeting the recommended requirements of the relevant part of the BS EN 60332-3 series. Where they are installed in one of the cable management systems listed in the regulation, BS EN 60332-1-2 applies instead. The listed systems are non-flame propagating conduit to BS EN 61386, trunking or ducting to BS EN 50085, cable tray or ladder to BS EN 61537, and powertrack to BS EN 61534. Fire-resisting cables meeting Regulation 560.8.1 are also permitted.
Cables must also have a minimum of 60% light transmittance when tested to BS EN 61034-2. A note to the regulation adds that non-fire resisting cables also need to meet the CPR requirements for reaction to fire. So a cable used in an escape route may need both a 60332-3 result and a CPR class.
What it means in practice
- Check which category was tested. A cable that passes category C (1.5 l/m) has not been shown to pass category A or B.
- A datasheet should name the part and category, for example EN IEC 60332-3-24 (category C).
- Do not read a 60332-3 pass as a CPR class, or a CPR class as a 60332-3 pass. They are separate tests with separate results.
Related reading: What is LSZH cable and when do you need it?.