BS 5467 vs IEC 60502 vs GB/T 12706: Armoured Cable Standards and Armour Coverage Tests
When a consultant writes "armoured cable to BS 5467" and the factory works to IEC 60502-1 or GB/T 12706.1, the two documents describe very similar products but not identical test obligations. Understanding the overlap prevents certificate arguments at inspection and, more importantly, prevents accepting a cable whose armour coverage or sheath thickness was never verified.
The Three Documents in One View
| Item | IEC 60502-1 / -2 | GB/T 12706.1 | BS 5467 / BS 6724 |
|---|---|---|---|
| Scope | 1 kV to 30 kV extruded insulation | 1 kV to 35 kV, harmonised with IEC | UK armoured LV and MV distribution cables |
| Voltage designation | U0/U (Um) | U0/U (Um) | 600/1000 V and 6350/11000 V style |
| Armour requirement | Defined coverage, galvanised steel wire or tape | Same principle, tape thickness table | Explicit wire diameter and tape thickness tables |
| Routine voltage test | 3.5 kV / 5 min at 0.6/1 kV | 3.5 kV / 5 min | 3.5 kV / 5 min |
| Sheath compounds | ST1, ST2, ST3, ST7 | ST1, ST2 equivalents | PVC or PE per UK practice |
| Usual acceptance | World Bank, ADB and international tenders | China, Southeast Asia, Africa, Middle East | UK DNOs, Gulf consultants |
Armour Coverage: The Test Buyers Forget
Armour coverage is the percentage of the cable circumference physically covered by the wires or tapes. IEC 60502 requires the interstice between adjacent wires to be small enough that a defined gauge cannot enter; BS 5467 additionally tables nominal wire diameters per cable size. A supplier that reduces wire diameter to save galvanised steel will pass a visual inspection and fail a coverage check.
- Ask for the armour wire diameter and the number of wires on the test certificate.
- Confirm the galvanising class — standard zinc coating versus heavy coating for corrosive soil.
- For tape armour, confirm tape thickness and the number of layers.
Test Regime Behind the Certificate
- Routine tests, every drum — conductor resistance to IEC 60228, dimensions, 3.5 kV / 5 min voltage test, and for MV constructions partial discharge.
- Sample tests — tensile and elongation of insulation and sheath before and after ageing, armour wire tensile, zinc coating mass.
- Type tests — electrical ageing, and for MV the impulse voltage and 4-hour AC test at elevated voltage.
Where a lender or consultant requires independent verification, KEMA or TUV type test reports for the exact construction are the recognised evidence. CE marking and a Declaration of Performance cover the European route.
Putting It in the Purchase Order
Write four things explicitly and most disputes disappear:
- The primary standard and edition, plus an accepted equivalent.
- Armour type, wire diameter and coverage class.
- Sheath compound and, if relevant, the flame test designation.
- The documentation set: routine test certificate per drum, type test report, and inspection rights before shipment.
Construction details and designations are in the armoured electrical cable guide.
