What UL94 V-0 actually costs a cable jacket: density, not elongation
Three flame-retardant jacket grades from the same line, with published data. The sacrifice people expect — elongation — does not appear. The one that does is density, and it changes cable OD and weight per metre.
The trade-off people expect
The standard assumption is that a V-0 jacket is a compromised jacket: flame retardant loading embrittles the compound, elongation drops, and the cable becomes stiff and crack-prone in service.
That assumption is worth testing against data rather than repeating. The three grades below are all halogen-free, all aromatic polyether, all intended for extrusion as a jacket, and all published on this site.
| Grade | UL94 | Density (g/cm³) | Elongation at break | Tensile strength |
|---|---|---|---|---|
| NL1285EV | V-2 | 1.19 | 455% | 26.5 MPa |
| NL1285FR | V-0 | 1.21 | 420% | 30.9 MPa |
| HFR85 | V-0 | 1.30 | 656% | 24.0 MPa |
Elongation is not where the cost lands
The V-0 grades do not collapse in elongation. NL1285FR sits at 420% against 455% for its V-2 sibling — a difference that in practice is absorbed by jacket wall design. HFR85 is the highest-elongation grade in the table at 656%, and it is V-0.
So "V-0 makes the cable brittle" is not supported by the numbers. What changes is the additive package, and the additive package is mostly mineral or phosphorus-based, which brings us to density.
Where the cost actually appears: mass and OD
Density runs from 1.19 to 1.30 g/cm³ across these three grades, about 9% at the top end. For the same wall thickness, jacket mass per metre rises with density one-for-one — so a 9% denser compound is roughly 9% more jacket weight, before any change in wall.
That matters twice. Cable weight per metre is a datasheet figure that customers compare directly, and OD is bounded by connector backshells, bend radius and conduit fill. A denser jacket either eats into those margins or forces a thinner wall — and a thinner wall is exactly where a UL94 rating stops being valid.
What a V-0 rating actually certifies
UL94 is a specimen test. The rating belongs to a stated thickness, so a compound rated V-0 at 1.5 mm is not V-0 at 0.4 mm, and the flame behaviour of the finished cable also depends on conductor, bedding and construction, not only on the jacket compound.
That is why the honest question to a supplier is not "is it V-0" but "at what wall thickness, on what construction, and do you have the test on the finished cable" — the compound's rating is the starting point of that conversation, not the end of it.