The four things that cause most order mistakes: the voltage designation, the conductor class, the temperature the cable will actually see, and the standard the buyer expects. All four are below.
Reading a designation
Chinese and IEC type codes look cryptic until you know that each letter and number stands for one layer of the cable. Take the example below apart and the rest follow the same pattern.
| YJ | Cross linked polyethylene (XLPE) insulation |
|---|---|
| V | PVC oversheath |
| 22 | Steel tape armour. The digits 32 mean steel wire armour, 42 mean a thicker steel wire armour for heavier duty |
| 3×120 | Three main conductors of 120 mm² |
| + 1×70 | One reduced neutral conductor of 70 mm² |
| 0.6/1 kV | Uo / U rating. See below |
| YJ | XLPE insulation |
|---|---|
| V (first position) | PVC insulation |
| V (later position) | PVC oversheath |
| L | Aluminium conductor, otherwise copper |
| ZR / Z | Flame retardant |
| WDZ | Low smoke, halogen free, flame retardant |
| NH | Fire resistant |
| P / P2 | Braided or taped screen on control cable |
| Uo | Voltage between a conductor and earth, that is, between the conductor and its metallic screen or sheath |
|---|---|
| U | Voltage between two conductors of the same cable |
| 0.6/1 kV | The standard low voltage cable, most LV distribution and building work |
| 3.6/6 up to 26/35 kV | Medium voltage, screened construction, generally for distribution feeders |
| Above 35 kV | High and extra high voltage, project specific design |
Conductors
Conductor class decides flexibility, termination method and price. Specifying a flexible class where a stranded class would do adds cost for no benefit; specifying a solid conductor where the cable has to bend during installation causes damage.
| Class 1 — solid | Single wire conductor. Small sizes for fixed wiring only, generally up to 10 mm². Cheapest, stiffest, and the easiest to damage if bent sharply. |
|---|---|
| Class 2 — stranded | Concentric stranded, circular or shaped. The default for power cable from 16 mm² upward, for fixed installation in ducts, trays and direct burial. |
| Class 5 — flexible | Fine wire stranded. Used where the cable has to be moved, or where termination is easier with a flexible conductor. |
| Class 6 — extra flexible | Finer wires still, for repeated flexing, welding cable, and small equipment connections. |
| Shaped conductors | Sector shaped stranded conductors above roughly 35 mm² reduce the overall cable diameter and allow higher density in ducts. |
If the standard does not state a class, the usual convention is Class 2 for power cable and Class 5 for flexible cable and building wire supplied in coils. Tell us if your drawings call for something different.
Temperature
The continuous conductor temperature is the number that fixes how much current a given size can carry. Two cables with identical copper content carry very different currents if one is insulated in PVC and the other in XLPE.
| PVC insulated | 70 °C continuous, 160 °C short circuit. Building wire, VV and BS 6346 type armoured cable. |
|---|---|
| XLPE insulated | 90 °C continuous, 250 °C short circuit. YJV, YJV22 and the medium voltage range. |
| LSZH, thermoplastic | 70 °C continuous, lower smoke and halogen emission than PVC. |
| LSZH, cross linked | 90 °C continuous, used where fire performance and higher current both matter. |
| Solar cable to EN 50618 | 90 °C continuous, 120 °C on the conductor, and resistant to UV and ozone over long outdoor exposure. |
| Minimum installation temperature | PVC compound roughly −5 °C, XLPE roughly −20 °C, solar cable typically −40 °C. Below these temperatures the cable must be warmed before bending. |
Current ratings depend on the installation method, the number of cables grouped together, the ambient air or ground temperature and the depth of burial. Send us the installation conditions and we will quote against the standard that applies.
Standards
The same physical cable can be tested and marked against several standards. What matters is that the cable is made to the standard your inspection authority will check.
| International / IEC | IEC 60502-1 for low voltage, IEC 60502-2 for medium voltage, IEC 60227 for PVC insulated cable, IEC 60228 for conductors |
|---|---|
| United Kingdom | BS 5467 for armoured power cable, BS 6724 for low smoke armoured, BS 6346 for PVC armoured, BS 6004 for building wire, BS 6387 for fire performance, BS 7870 for aerial bundled |
| Germany | DIN VDE 0276-603 and 0276-620 for power cable, DIN VDE 0281 for PVC insulated |
| United States | UL 44 and UL 83, ICEA S-95-658 for power cable, ASTM B231, B232 and B399 for bare conductor |
| France and North Africa | NF C 33-209 for aerial bundled cable, NF C 32-321 for low voltage cable |
| Australia and New Zealand | AS/NZS 5000.1 |
| Solar installations | EN 50618 and IEC 62930, with TUV 2 PfG 1169 as the common European approval |
| Russia and CIS | GOST 31996 for power cable with plastic insulation |
| Fire performance | IEC 60332 for flame propagation, IEC 60754 for halogen acid gas, IEC 61034 for smoke density |
Specification
If you can answer these, a supplier can quote accurately instead of guessing and then revising the price after the order.
Buried direct, in duct, on a tray, in free air, or overhead. This decides armouring, sheath and current rating.
Fixed installation allows a stranded conductor. Anything that moves requires Class 5 or Class 6.
This sets the Uo / U rating and whether a screened construction is needed.
Ambient air or ground temperature, and whether the cable will be grouped with others.
Flame retardant, fire resistant, low smoke and halogen free are three different requirements, often confused with each other.
Rodent, backfill and site traffic decide between steel tape and steel wire armour.
Drum length affects both price and how much fits in the container.
We read cable schedules and drawings as they are. If your document is in Chinese, French, Russian or Spanish, send it anyway.
If a specification in your file cannot be met at the price you have in mind, we will say so at quotation stage and propose the nearest alternative that still meets the standard.
Describe the installation and the load. We will suggest the type, size and standard, and then quote it.