Selection aid
Break load and strength-to-weight calculator
Turn the verified tensile band of each CCS grade into a break-load range for any diameter, then weigh it against the conductor's own weight: the strength-per-weight case for a steel-core conductor, in numbers you can check.
For the weight term. Floor 10% per ASTM B452.
Anchors: tensile bands 1200-1400 / 900-1100 / 700-900 / 600-800 MPa (verified grade data); densities 8.89 / 7.85 g/cm³ (IEC 60028 / steel table value). Break load = band × cross-section.
Result
Break load range (kN)
-
Weight (kg/km)
-
kN per kg/km
-
Ultimate figures. Derate for working load. Stranded builds carry their own verified band (500-1300 MPa overall) and are quoted separately.
| Diameter | 21% (kN) | 30% (kN) | 40% (kN) | 55% (kN) |
|---|---|---|---|---|
| 1.00 mm | 0.9-1.1 | 0.7-0.9 | 0.5-0.7 | 0.5-0.6 |
| 2.00 mm | 3.8-4.4 | 2.8-3.5 | 2.2-2.8 | 1.9-2.5 |
| 3.00 mm | 8.5-9.9 | 6.4-7.8 | 4.9-6.4 | 4.2-5.7 |
| 4.00 mm | 15.1-17.6 | 11.3-13.8 | 8.8-11.3 | 7.5-10.1 |
Break-load ranges per grade from the verified bands (21%: 1200-1400 · 30%: 900-1100 · 40%: 700-900 · 55%: 600-800 MPa). Ultimate values. The working load is a derate of these, set by your sag, ice and termination case.
Frequently Asked Questions (FAQ)
Where do the tensile bands come from?
The verified grade data itself: 21% at 1200-1400 MPa, 30% at 900-1100, 40% at 700-900, 55% at 600-800. To turn a band into a break-load range the tool multiplies the low and high ends by cross-section. Pure arithmetic, no fitting.
Is break load the same as working load?
No, and the gap between them is the safety factor. Break load here is the ultimate tensile figure. Real installations derate it for sag, ice, vibration and termination efficiency. Treat the output as the ceiling your working load must stay well under, never as a working load.
How is strength-to-weight expressed?
As kilonewtons of break load per kg/km of conductor weight. A screening index: higher means more load capacity per unit of structure and shipping weight. The tool also shows the solid-copper build at the same gauge so the index can be compared honestly. Solid copper's band depends on temper, which is why the comparison is presented per specification rather than averaged.
Why does the lower-conductivity grade win the index?
Because the steel core does the mechanical work. The 21% grade's 1200-1400 MPa core carries the span while its copper skin carries signal, and conductivity is bought separately. That division of labour is the entire CCS proposition, and the index makes it visible.
Does stranding change the break load?
Yes. Stranded constructions carry their own verified band (500-1300 MPa overall) because lay geometry and strand count affect load transfer. The calculator models solid single-end wire. For stranded builds, quote against the construction.
Need the span worked out on real stock?
Send the grade, diameter and load case. We quote CCS against its verified tensile band with a heat-number-traceable MTC.