NAYY Aluminum Cables Selection Guide
NAYY is an underground cable with an aluminum conductor, PVC insulation and PVC sheath (Turkish code YAVV); the choice comes down to single-core versus multicore construction.
This guide explains what to look at when choosing products in the NAYY Aluminum Cables category.
The NAYY code and its place in the alvinal family
The letters of the code give the construction in order: N standard-type cable, A aluminum conductor, first Y PVC insulation, second Y PVC outer sheath. The Turkish code is YAVV; in the HES Kablo datasheet it appears as YAVV-R, where the final R indicates a stranded (multi-wire) rigid conductor. In multicore constructions the gaps between the cores are filled with filler. The maximum operating temperature in the datasheet is 70 °C.
Alvinal is the general name for underground cables with aluminum conductors. The unarmored type without a concentric conductor carries the code YAVV (NAYY); alvinal types with a concentric conductor or armor are referred to by other codes and are not part of this category.
Choosing between single-core and multicore construction
- Multicore cable is pulled in one go, but it becomes heavier as the cross-section grows and needs a wider bend at turns. In the datasheet the minimum bending radius is 12 times the cable outer diameter; for a 3x185 mm² cable with an outer diameter of about 51 mm, this comes to about 61 cm.
- Single-core cable (1x) allows each phase to be pulled separately in large cross-sections. Whether the phases are laid side by side or in a trefoil (triangular) bundle changes the current carrying capacity; the datasheet gives separate values for the two arrangements. According to the manufacturer's technical notes, steel pipes are not used where single-core cables pass through; an anti-magnetic pipe is chosen, or all three phases are passed through the same pipe in a trefoil bundle.
A three-core cable carries only the phase conductors on a three-phase line; how the neutral, protective or PEN conductor is provided is determined in the project.
NAYY cross-section for the same current as copper NYY
Aluminum has a higher resistance than copper: in the HES datasheets, the DC resistance of a 70 mm² conductor at 20 °C is 0.268 Ω/km for copper and 0.443 Ω/km for aluminum. In the same datasheets, under the same installation condition, a 3x70 mm² copper NYY carries 228 A in soil and a 3x70 mm² NAYY carries 176 A. In these tables, the first NAYY cross-section that matches the NYY value is 3x120 mm² (242 A); at about 2500 kg/km, this cable is still lighter than the 3x70 mm² NYY (about 2900 kg/km). Because the cross-section is larger, the outer diameter, lug and gland sizes also grow.
On long runs, voltage drop usually determines the cross-section. The voltage drop calculation tool lets you make a preliminary check with the aluminum conductor option; the final cross-section is determined by the project calculation.
Which conditions the current carrying table applies to
The values in the datasheet are for a specific reference condition: in soil, 20 °C soil temperature, 70 cm laying depth, 1 K.m/W soil thermal resistivity and a load factor of 0.7; in air, 30 °C ambient temperature; single circuit in both cases. If the conditions differ, the value is multiplied by correction factors. For example, the factor the manufacturer gives for 1 kV cables is 0.87 at an air temperature of 40 °C; the 158 A in-air value of a 3x70 mm² NAYY drops to about 137 A in this environment. Other cables on the same route and dry soil also reduce the value.
For installation on surfaces and in pipes or ducts, the cable current carrying capacity calculation tool gives a preliminary value for aluminum conductors; it does not cover underground installation.
Connecting an aluminum conductor
An aluminum surface oxidizes quickly in air, and direct contact with copper causes corrosion in a humid environment. For this reason, aluminum-to-copper bimetal lugs are used when connecting to a copper busbar or a device with copper terminals. The lug barrel is chosen according to the conductor cross-section and the hole diameter according to the connection bolt; whether the device terminal block accepts an aluminum conductor is checked in the manufacturer's data.
The difference between NAYY and NA2XH
NA2XH aluminum cables also have aluminum conductors; in the HES datasheet the insulation is XLPE, the outer sheath is a halogen-free (HFFR) compound, and the maximum operating temperature is 90 °C compared with 70 °C for NAYY. For this reason a higher current value is given at the same cross-section: for 3x70 mm² in air, NAYY 158 A, NA2XH 189 A. The datasheet defines the use of NA2XH as places that are fire-sensitive and densely occupied by people, such as hotels, schools, hospitals and high-rise buildings. In the NAYY datasheet, the use is power centers, industrial facilities and local energy distribution; the cable is installed inside and outside buildings, underground and in cable trunking.
Comparison and selection table
| Selection Criterion | NAYY (Aluminum Conductor Power Cable) | NYY (Copper Conductor Equivalent) | Engineering & Termination Rules |
|---|---|---|---|
| Conductor Material | Solid or stranded aluminum (Al) conductor | Bare annealed copper (Cu) conductor | Step up 1–2 cross-section sizes in NAYY for equal ampacity |
| Weight & Cost | Significantly lighter weight & lower conductor cost per meter | Higher conductivity (56 vs 35 m/Ω·mm²), smaller outer diameter | NAYY excels on long underground utility & street-lighting feeders |
| Common Sizes | 4×16, 4×25, 4×35, 4×50, 3×70/35 – 3×240/120 mm² | Full range from 1.5 mm² up to 300+ mm² | Aluminum power cables are standardized from 16 mm² upward |
| Lugs & Termination | Requires Bimetallic (Al-Cu) lugs + oxide-inhibiting compound | Standard tin-plated copper (SKP) compression lugs | Never bolt bare aluminum directly to copper busbars (galvanic corrosion) |
Frequently asked questions
Is an alvinal cable the same as NAYY?
Alvinal is the general name for underground cables with aluminum conductors and covers several types. The unarmored type without a concentric conductor carries the code YAVV (NAYY) and appears as Alvinal-D in technical sources. The type with a concentric conductor is coded NAYCY, and the steel-armored type NAYFGbY. If you are searching under the name alvinal, stating the code and the core construction in the order avoids confusion.
How many amperes does a NAYY cable carry?
The value depends on the cross-section and the installation condition. The HES datasheet gives, for 3x70 mm² NAYY, 176 A in soil and 158 A in air; for 3x185 mm², 308 A in soil and 289 A in air. These values are for a single circuit at 20 °C soil temperature, 70 cm depth and 30 °C air temperature. A hotter environment, dry soil or several cables side by side lower the value; correction factors are applied.
Can an aluminum cable be connected directly to a copper busbar?
Direct contact between aluminum and copper causes galvanic corrosion and increased contact resistance in a humid environment. For this reason, an aluminum conductor is connected to a copper busbar or copper terminal with a bimetal lug that has an aluminum barrel and a copper connection surface. When entering a device terminal block directly, whether the terminal block accepts an aluminum conductor is checked in the manufacturer's data; the crimping die is chosen according to the lug manufacturer's data.
What is the difference between NAYY and NYY?
Both are PVC-insulated, PVC-sheathed power cables in the 0.6/1 kV class; the difference is in the conductor. NYY has a copper conductor, NAYY an aluminum one. In the HES datasheets, under the same condition in soil, a 3x120 mm² NYY carries 313 A and a 3x185 mm² NAYY carries 308 A; for a similar current, NAYY is selected with a larger cross-section, yet the cable is still lighter. A bimetal lug is required at copper connection points.
Can NAYY cable be used inside buildings?
The manufacturer datasheet lists power centers, switchgear and industrial facilities and local energy distribution as the application for NAYY, and outdoor, indoor, underground and cable trunking as the places of installation. Its insulation and sheath are PVC. In buildings with a halogen-free cable requirement, NA2XH with XLPE insulation and a halogen-free sheath is selected for the same job; the project and the fire regulation determine the requirement.