What Is N2XSY Cable? YXC7V-R Medium-Voltage Cable Selection
N2XSY is a single-core medium-voltage cable with XLPE insulation, a copper screen and a PVC sheath; its Turkish standard equivalent is YXC7V-R. It is chosen by voltage class, conductor and screen size, and installation method.
This guide explains what to check when choosing products in the N2XSY Cables category. Its aluminum-conductor counterpart, NA2XSY cables, has the same construction.
What is N2XSY cable?
N2XSY is a single-core medium-voltage power cable with a copper conductor, XLPE insulation, a copper wire screen and a PVC outer sheath. Its Turkish standard equivalent is YXC7V-R, and that of the aluminum-conductor NA2XSY is YAXC7V-R. The data sheets of the HES Kablo and Prysmian Kablo products in the category cite the TSE K 204 criteria; the HES data sheet also refers to TS HD 620 S3 and the Prysmian data sheet to IEC 60502-2.
In the VDE-based code, the letters read as follows:
| Letter | Meaning |
|---|---|
| N | VDE standard cable, copper conductor (if there is no A) |
| 2X | XLPE (cross-linked polyethylene) insulation |
| S | Copper screen |
| Y | PVC outer sheath |
Cable construction
The Prysmian data sheet lists the construction from the inside out: stranded copper conductor, inner semiconducting layer, XLPE insulation, outer semiconducting layer, semiconducting crepe paper, copper wire screen with a copper retaining tape, protective tape and PVC outer sheath. The semiconducting layers spread the electric field evenly in the insulation; the copper screen confines the electric field within the insulation, keeps the cable surface at earth potential and carries earth fault and capacitive currents. For the 90 °C and 250 °C limits of XLPE insulation, see the what is XLPE cable guide.
What do 20.3/35 kV and 1x120/16 mean?
- 20.3/35 kV: the first value (U0) is the rated voltage between phase and earth, the second (U) between phases. The HES data sheet also gives 20.8/36 kV in brackets. All products currently in the category are in this voltage class. The 20.3/35 kV class is used for 34.5 kV distribution networks in Turkey; for other network voltages the class is chosen by the project.
- 1x120/16 mm²: a single-core cable with a 120 mm² conductor and a 16 mm² copper screen. The screen size is chosen by the earth fault current and duration of the network; the same conductor size can come with different screen sizes.
- Three-phase line: N2XSY is single-core, so a three-phase line uses three separate cables and the cable length is calculated accordingly.
Current ratings by size
The values below are from the HES data sheet: 20 °C ambient in the ground and 30 °C in air, for cables laid side by side (flat) and in trefoil. The Prysmian data sheet gives similar values for the same sizes and states its conditions as 1 K·m/W soil thermal resistivity and a 0.7 load factor. A 0.7 load factor means the ground ratings assume cyclic loading rather than continuous full load; continuous full load needs a lower value.
| Size | Ground, flat | Ground, trefoil | Air, flat | Air, trefoil | Outer diameter | Max. DC resistance (20 °C) |
|---|---|---|---|---|---|---|
| 1x35/16 mm² | 214 A | 192 A | 233 A | 202 A | 34.5 mm | 0.524 Ω/km |
| 1x70/16 mm² | 306 A | 276 A | 348 A | 299 A | 37.5 mm | 0.268 Ω/km |
| 1x95/16 mm² | 363 A | 329 A | 421 A | 362 A | 39.5 mm | 0.193 Ω/km |
| 1x120/16 mm² | 410 A | 373 A | 483 A | 416 A | 41.5 mm | 0.153 Ω/km |
| 1x150/25 mm² | 449 A | 415 A | 540 A | 469 A | 43.0 mm | 0.124 Ω/km |
| 1x240/25 mm² | 576 A | 541 A | 718 A | 630 A | 47.5 mm | 0.0754 Ω/km |
Soil temperature, soil thermal resistivity, burial depth and the number of circuits in the same trench change these values; the final rating is calculated with the manufacturer's correction factors.
Difference between N2XSY and NA2XSY
NA2XSY has an aluminum conductor; at the same size it carries less current but is lighter and has a lower conductor cost. In the HES data sheets, a 1x95/16 mm² cable laid flat in the ground carries 363 A as N2XSY and 284 A as NA2XSY; the DC resistance at 20 °C is 0.193 and 0.320 Ω/km respectively. Choose terminations and joints suitable for an aluminum conductor.
Installation and connection
- Bending radius: the HES data sheet gives a minimum bending radius of 15 times the outer diameter; for 1x120/16 mm² that is about 62 cm.
- Installation temperature: the Prysmian data sheet requires the cable to be laid at 0 °C or above.
- Laying formation: the HES data sheet gives higher current ratings for flat than for trefoil formation; the difference depends on how the screens are earthed and on the spacing between cables. Inductance is lower in trefoil (0.388 versus 0.585 mH/km for 1x120/16).
- Single-core cable: do not run the phases individually through steel conduit or ferromagnetic clamps; induced currents cause heating. Keep the three phases together.
- Terminations and joints: choose cable terminations and joints for the cable's voltage class, conductor size and conductor material, and have them made by authorized jointers.
- Screen earthing: whether the copper screen is grounded at one end or both ends is decided by the project design, and this choice also affects the current rating.
- Testing: the 3.5 U0 (AC) in the Prysmian data sheet is the factory test voltage, not a site test value. Post-installation tests follow the project specification and are done by authorized personnel.
Frequently asked questions
What voltage is N2XSY cable rated for?
The data sheets of the N2XSY and NA2XSY products in the category give a rated voltage of 20.3/35 kV (U0/U); the HES data sheet also gives 20.8/36 kV.
What does N2XSY 1x120/16 mean?
A single-core cable with a 120 mm² copper conductor and a 16 mm² copper screen. A three-phase line needs three cables.
Where can I see N2XSY cable prices?
Current prices per meter are shown in the N2XSY Cables category. Some sizes are available on quotation only.