IEC 60754 cable: what the standard actually governs
Searches for IEC 60754 cable usually land on four reports that do not line up: 60754-1, 60754-2, 61034-2 and 60332-3-24. These are four different tests, not four editions of one. Acid gas quantity, acidity and conductivity of the gas, smoke density, and bundle flame propagation. “Complies with IEC 60754” says nothing until it names the part and the limit.
Standards are grouped by what they measure: gas composition (60754, 50267), optical density (61034), flame propagation (60332, 50399). Each group gets its limit values and the way the result usually appears on a report.
How the classes are cut
IEC 60754-1 burns a weighed sample in a tube furnace, scrubs the gas and titrates or runs ion chromatography; the result is mg/g of acid gas, with 5 mg/g as the usual limit. IEC 60754-2 measures pH and conductivity of the same kind of solution, typically pH ≥4.3 and ≤10 µS/mm. One gives a quantity, the other an acidity, and the report must name the part.
Standard | What it covers | Key limit | Who runs it |
IEC 60754-1 | Acid gas quantity | ≤5 mg/g | Third-party lab |
IEC 60754-2 | Acidity and conductivity | pH ≥4.3, ≤10 µS/mm | Third-party lab |
IEC 61034-2 | Smoke density | ≥60 % transmittance | Third-party lab |
IEC 60332-3-24 | Bundle burn, Cat C | Char ≤2.5 m | Third-party lab |
EN 50399 | Heat release and flame spread | Mapped to Euroclass | Lab with a large burn room |
EN 13501-6 | Classification rules | No test, classification only | Notified body |
The test method decides whether classes can be compared at all
IEC 60332-3 grades by non-metallic volume per metre: Cat A 7 L/m, B 3.5, C 1.5, D 0.5. The same cable lands in a different Cat depending on how many cores are bundled. When a spec says “Cat C” it means tested at 1.5 L/m; tying ten large cables together and calling the result Cat C does not hold.
IEC 60754-2 requires both pH ≥4.3 and conductivity ≤10 µS/mm. Reports that quote a passing pH with conductivity above the limit usually indicate soluble salt residue — either in the filler or left by an incomplete surface treatment. Checking pH alone misses that whole class of problem.
The class on the certificate is not the cable in your hand
A Euroclass certificate dies quietly when the construction changes. Testing a 4 × 6 mm² sample and shipping 4 × 16 mm² increases the non-metallic volume and changes the bundle test conditions, so the original classification no longer applies. “Same compound” is not the same product.
A usable test file answers four questions on every page: which construction was tested, which edition of the standard, which laboratory, and which specimen. Tender submissions usually fail on the second and fourth — an edition that has since been superseded, or a specimen whose core count and cross-section do not match the offered product.
65 % and 78 % transmittance on the same cable can both be genuine. IEC 61034-2 responds to sample volume, flame position and chamber soot; a 20 % difference in sample mass moves the minimum transmittance by 8–12 points. Before comparing two suppliers, compare the sample length and number of cores in their reports.
Where the sample came from changes the answer. A sheath slice taken from the middle of a finished cable carries extrusion orientation and a known crosslinking gradient; a pressed pellet carries neither. Labs report 3–5 points of difference in oxygen index between the two on the same compound. If the report does not say which one was tested, the number cannot be compared with anyone else’s.
An LSZH sheath usually carries a 90 ℃ continuous rating and 250 ℃ for 5 s under short circuit; crosslinked versions reach 105 or 125 ℃, though 60 % filler makes 125 ℃ difficult. The 90 ℃ refers to the sheath, not the insulation. If the insulation is XLPE the conductor can run hotter, and ampacity has to be calculated on the conductor, not on the sheath figure.
How to read a test report
- File reports by what they measure: gas, smoke, flame
- Record the standard number with its edition year, since an edition change invalidates old reports
- Confirm whether 60754-1 or -2 is on file, because the criteria differ
- For 60332, record the Cat and the number of cores tested
- For 61034, keep the transmittance curve and sample length so labs can be compared
An oxygen index of 32 versus 38 often reflects where the sample came from, not the formulation. Pressed compound pellets read higher than sheath slices taken off a finished cable, because extrusion orientation and crosslinking change burning behaviour. A tender that says “OI ≥32” must also say where the sample is taken.
The specimen description matters more than the conclusion line. A B2ca report stating four cores of 6 mm² at 3.5 m does not cover an order of four cores at 16 mm², because the non-metallic volume changed and the classification followed the specimen. Reading page two of the report is the fastest part of a review.
Acceptance needs three documents that do not substitute for one another: a type test report proving the construction once passed; batch routine tests proving this delivery matches the sample (sheath thickness, diameter and conductor resistance, typically on a 5 % sample); and an independent witness test proving the compound was not quietly changed after approval. The first two come from the factory — which is exactly why the third one carries the weight.
A single cable can pass Cat C and the assembly fail it. Fillers, tapes and inner sheath all count as non-metallic material; adding them easily takes the volume from 1.4 to 1.8 L/m, past the 1.5 L/m Cat C ceiling. Test the assembly, declare the assembly, or expect a downgrade at sampling.
Related: LSZH cable; B2ca cable class.
Frequently asked questions
Which 60332 Cat applies?
It follows non-metallic volume per metre: A is 7 L/m, B 3.5, C 1.5, D 0.5. Dense trays and vertical shafts take A or B, ordinary horizontal tray takes C, single cables can use D. Most specs name the Cat directly.
Do I need both 61034 and 60332?
Yes — one measures smoke, the other flame propagation, and neither replaces the other. A complete LSZH test package contains 60754-1, 60754-2, 61034-2 and 60332-3.
How long is a test report valid?
The standard sets no expiry, but tenders commonly require reports under three years old, and an edition change invalidates older ones. Since EN 50575 moved to 2014+A1:2016, some projects require retesting to the new edition.
How many parts does IEC 60754 have?
Two. Part 1 measures total acid gas in mg/g; part 2 measures pH and conductivity of the absorption solution. The criteria differ, and part 2 needs both figures to pass.
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