HD 603, HD 620 and IEC 60502: which standard sits behind your power cable

The datasheet of a power cable often lists two kinds of standard side by side: an international IEC standard and a European harmonisation document, an HD. IEC 60502 gives one set of requirements for cable with extruded insulation. The HDs define the European cable types, per country in a section of their own. For low voltage that is HD 603 or HD 604, for medium voltage HD 620.

There is a reason these power cable standards are HDs and not ENs. Every country has to adopt an EN word for word. An HD only has to be announced, and conflicting national standards have to go. That lets the differences between countries remain. Part 1 of an HD holds the general requirements; the actual cable types are in sections with a part number and a letter, such as 3-G or 10-C. The standard itself does not link those letters to countries. The national adoptions do that: NEN-HD, NBN HD and DIN VDE 0276.

HD 603 covers cable for 0.6/1 kV in underground distribution networks, mainly public ones. The part number tells you the insulation and whether the cable is armoured: part 3 is PVC unarmoured, part 5 XLPE unarmoured and part 6 XLPE armoured. The German NYY falls under section 3-G, issued in Germany as DIN VDE 0276-603. The Belgian EXVB, EXGB, EAXeVB and EAXeGB fall under NBN HD 603 section 5-A, and the armoured EXAVB under 6-E.

YMvK and VG-YMvKas are not in HD 603 but in HD 604. That standard covers cable for 0.6/1 kV and 1.9/3.3 kV with fire performance requirements, mainly intended for power stations and substations. YMvK and VG-YMvKas fall under section 4-D, the halogen-free YMz1K under 5-C. The Belgian XVB falls under NBN HD 604-4-G and XGB under 5-L.

HD 620 covers medium voltage cable with extruded insulation, from 3.6/6 (7.2) kV up to and including 20.8/36 (42) kV. XLPE cable is in part 10. The German N2XS(F)2Y and NA2XS(F)2Y fall under section 10-C in the 6/10, 12/20 and 18/30 kV classes, the Belgian EAXeCWB and EAXeCGB under 10-B, and the Netherlands has section 10-J. The current edition is HD 620 S3:2023. It replaces S2, which had to be withdrawn by 13 March 2026 at the latest.

IEC 60502-1 applies to 1 and 3 kV, IEC 60502-2 to 6 up to and including 30 kV (Um 36 kV). There is a boundary here that is often overlooked in practice. The 20.8/36 kV class falls within HD 620 but outside IEC 60502-2. Above Um 36 kV, IEC 60840 applies internationally; in Europe HD 632 only takes over above Um 42 kV. For 20.8/36 kV the standard in Europe is therefore HD 620.

Under IEC 60502-2 and the German DIN VDE 0276-620, the routine test on every length is a voltage test of 3.5 × Uo for five minutes. At 6/10 kV that is 21 kV, at 12/20 kV 42 kV and at 18/30 kV 63 kV. For 20.8/36 kV the same rule comes to 72.8 kV. The nominal XLPE insulation thickness under IEC 60502-2 is 3.4 mm at 6/10 kV and 5.5 mm at 12/20 kV.

What does "to HD 620" cover in a specification? The construction, the insulation thickness, the marking and the testing: type tests, sample tests and the routine test on every length. Without a section the reference is incomplete, because the types only appear in the sections. Three things do not follow from the reference to HD 620 alone. The CPR class comes from EN 50575 and is stated separately in the declaration of performance. Whether the cable is longitudinally watertight depends on the type, such as the (F) in N2XS(F)2Y. And whether the sheath is flame-retardant also depends on the type: a PE sheath is not.

For the buyer: on medium voltage, ask for the section, not only the standard. HD 620 10-C and NBN HD 620 10-B describe different cables, with a different construction and sometimes a different insulation thickness.