Cables and wires in the EU: designations, standards and selection

In Poland, installers use both national designations (such as YDY, YKY, LgY, or OMY) and harmonised codes (such as H05VV-F, H07V-K, or H07RN-F). Wires up to 450/750 V are described by EN 50525, while 0.6/1 kV cables follow PN-HD 603. Additionally, fixed building cables must comply with CPR regarding fire reaction classes.

Two designation systems you will meet in a catalogue

When browsing electrical component catalogues or technical datasheets in the Polish market, you will encounter two distinct designation systems operating in parallel. The first is the national letter-based system, which includes designations such as YDY, YDYp, YKY, YAKY, YKXS, DY, LgY, OMY, OMYp, OW, OWY, OnPD, YKSY, YKSLY, and AsXSn. The second is the harmonised system, which follows the nomenclature defined in the PN-HD 361 S4:2021-07 standard ("System oznaczeń przewodów"). This harmonised system uses codes such as H03VV-F, H05VV-F, H05RR-F, H07RN-F, H05V-U, H07V-U, H07V-K, and H07Z1-K.

The coexistence of these two systems does not hinder correct selection, provided the installer understands the relationship between them. In many cases, the same product is described using both designations simultaneously to ensure clarity for both local installers and international designers. For example, the national designation DY corresponds to the harmonised H07V-U, while LgY is the equivalent of H07V-K. Similarly, OMY can represent H03VV-F or H05VV-F, OnPD corresponds to H07RN-F, and OW is the equivalent of H05RR-F.

It is also important to distinguish between regional nomenclature and local installation standards. For instance, you may encounter the German designation NYM in various technical documents. While NYM products are available on the Polish market, the standard national equivalent for installation purposes is YDY.

How to read the Polish letter code

In the Polish electrical market, cable designations follow a specific letter-based coding system that describes the construction, insulation, and conductor type. The code typically follows a sequence where each letter represents a specific physical or material characteristic.

The first letters generally define the insulation and sheath materials. For instance, the letter 'Y' denotes PVC insulation or sheathing, while 'X' indicates cross-linked polyethylene (XLPE). If the designation includes 'K', it identifies the product as a power cable, whereas 'S' refers to signal or control cables. The presence of 'A' signifies aluminium conductors, while 'L' and 'D' distinguish between multi-strand (flexible) and single-strand (solid) conductors, respectively.

Mechanical protection and specific forms are also integrated into the code. A 'p' suffix indicates a flat construction, whereas 'żo' denotes the presence of a protective conductor. For applications requiring higher mechanical resistance, 'Ft' or 'Ftl' indicates steel tape armouring, and 'ekw' refers to shielded versions. For specialized uses, such as workshop or heavy-duty environments, specific prefixes like 'OW' (rubber insulation) or 'OMY' (lightweight PVC for domestic appliances) are used to categorize the cable's intended application.

Letter/Code	Meaning
Y	PVC insulation or sheath
X	Cross-linked polyethylene (XLPE)
D	Single-strand conductor (solid)
L	Multi-strand conductor (flexible)
g	Flexible
A	Aluminium
K	Power cable
S	Signal or control cable
p	Flat construction
żo	With protective conductor
Ft / Ftl	Steel tape armouring
ekw	Shielded

Examples of common designations:

• YDY: A round cable with PVC insulation and sheath featuring single-strand conductors.
• YDYp: The flat version of the YDY cable.
• YKYFtl: A power cable with PVC insulation, featuring steel tape armouring.
• YAKY: A power cable with PVC insulation and aluminium conductors.
• YKXS: A power cable with XLPE insulation.
• LiYCY: A shielded control cable.
• LiYY: A non-shielded control cable.

The harmonised code: what H07V-K means

The harmonised designation system provides a standardised way to identify the technical characteristics of a cable. The first part of the code specifies the rated voltage. For instance, the "03" designation refers to 300/300 V, "05" indicates 300/500 V, and "07" denotes 450/750 V.

The subsequent letters in the designation describe the materials used for the insulation and the outer sheath. In this system, "V" represents PVC, "R" denotes rubber, and "S" stands for silicone rubber. For applications requiring low smoke emission, the designations "Z" or "Z1" are used to identify halogen-free materials.

The final part of the code defines the conductor construction. The suffix "-U" indicates a single-wire conductor, while "-R" refers to a round multi-wire conductor. For fixed installations, the "-K" designation identifies a flexible stranded conductor, whereas "-F" is used for flexible stranded conductors intended for connection leads. To illustrate these combinations: H07V-U is a rigid installation cable rated at 450/750 V, while H07V-K is its stranded version. Other examples include the H05VV-F, a flexible connection lead rated at 300/500 V, and the H07RN-F, a heavy-duty sheathed cable with rubber insulation.

Cables up to 450/750 V — the EN 50525 series

For low-voltage applications where the rated voltage does not exceed 450/750 V, the relevant regulatory framework is provided by the EN 50525 series. This series is composed of 18 distinct parts, with Part 1 establishing the general requirements for the entire range. The EN 50525:2011 series replaced the previous harmonised documents, PN-HD 21 and PN-HD 22, which were withdrawn in 2011.

The scope of the EN 50525 series is strictly limited to voltages up to 450/750 V. For installations requiring 0.6/1 kV cables, designers and installers must refer to different standards, as the EN 50525 series does not cover those higher voltage ratings.

Within this series, several parts are critical for standard electrical installations. The following table outlines some of the most significant parts and the specific cable types they cover:

Standard Reference	Cable Type and Description
PN-EN 50525-2-11	Flexible PVC insulated cables (H03VV-F and H05VV-F)
PN-EN 50525-2-21	Flexible elastomer insulated cables (H05RR-F and H07RN-F)
PN-EN 50525-2-31	Single-core non-sheathed PVC insulated cables (H05V-U/-K and H07V-U/-K)
PN-EN 50525-3-31 and 3-41	Single-core halogen-free cables with low smoke emission (H07Z1-U/-K and H07Z-U/-K)

Power cables 0.6/1 kV

The primary standard for these cables is PN-HD 603 S1:2006, including the A3:2009 amendment. For cables designed for power plants that require flame retardancy, the applicable standard is PN-HD 604 S1:2002. On an international level, the IEC 60502-1 document serves as the global reference for this group. Since IEC 60502-1 does not have a direct European implementation as an EN standard, manufacturers typically certify their products by referencing both PN-HD 603 S1 and IEC 60502-1 simultaneously.

The Polish market offers several common cable constructions depending on the conductor material, insulation type, and mechanical requirements. Common designations include:

• YKY: Copper conductor with PVC insulation.
• YAKY: Aluminium conductor with PVC insulation.
• YKXS: Copper conductor with XLPE insulation.
• YKYFtl and YKXSFtl: Armoured versions featuring steel tape armouring.

For overhead lines and service connections, insulated self-supporting cables such as the AsXSn type are used. These cables feature aluminium conductors and XLPE insulation, specifically designed to withstand the mechanical stresses of aerial installations.

Conductors: solid or stranded, classes 1, 2, 5 and 6

The construction and electrical resistance of conductors are governed by the PN-EN IEC 60228:2025-02 standard, which has replaced the previous PN-EN 60228:2007 version. This standard provides the framework for classifying conductors based on their physical structure, ensuring that cables from different manufacturers remain comparable by defining maximum allowable resistances for the conductor.

Conductors are categorized into several distinct classes:

• Class 1: A solid conductor.
• Class 2: A stranded conductor intended for fixed installations.
• Class 5 and Class 6: Flexible conductors, where Class 6 offers greater flexibility than Class 5.

When working with flexible conductors (Class 5 and Class 6), it is critical to use cable ferrules before connecting them to a screw terminal. Attempting to tighten a screw directly onto the strands will cut through part of the wires, which degrades the quality of the contact and the overall integrity of the connection.

CPR: the reaction-to-fire class of every cable

Cables and wires installed permanently in buildings are classified as construction products under the European Parliament and Council Regulation (EU) No 305/2011 (CPR). Since 1 July 2017, manufacturers have been legally required to issue a Declaration of Performance (DoP) and mark the product with the CE sign, which must include information regarding its reaction to fire class. Regulation (EU) 2024/3110 will replace the current CPR, with its primary application beginning on 8 January 2026, subject to long transitional periods.

For electrical installers and designers, the technical basis for selection lies in two key standards: PN-EN 50575 serves as the harmonised standard for cables, while PN-EN 13501-6 defines the classification of their reaction to fire. When inspecting a cable's sheath, the marking should clearly indicate the reaction class. For classes from Dca and higher, additional criteria are appended to the classification to describe specific fire behaviors: s (smoke emission), d (flaming droplets), and a (acidity of combustion products).

The reaction to fire classes are ranked from the best to the worst as follows: Aca, B1ca, B2ca, Cca, Dca, Eca, and Fca. In practical market applications, you will most commonly encounter classes ranging from B2ca to Fca. For example, a typical YDY installation cable usually carries a class of Eca or Dca, whereas halogen-free N2XH cables can achieve a classification of B2ca-s1,d0,a1.

From a regulatory standpoint in Poland, the technical building regulations do not specify a minimum required reaction to fire class for cables; instead, they provide a descriptive requirement that cables must not spread fire. For professional guidance on selecting classes based on the specific type of building or installation, designers may refer to the voluntary association standard N SEP-E-007.

Fire resistance is a second, separate axis

Reaction to fire (CPR classes) and fire resistance are two different properties: While the former describes how a material contributes to the spread of fire, fire resistance refers to the ability of a cable to maintain circuit continuity during a fire.

Fire resistance is characterized by specific symbols such as FE180, PH90, or E90. The testing methodology for these properties is governed by PN-EN 50200, while the continuity of circuits for cables up to 0.6/1 kV is tested according to PN-IEC 60331-21. In the Polish market, fire-resistant cables intended for powering fire protection equipment are identified by the designations HDGs and HDGsżo, whereas signaling versions are marked as HTKSH and HTKSHekw. These cables are easily recognizable by their red outer sheath.

For halogen-free cables, additional testing is required to ensure safety in the event of combustion. These supplementary tests include:

• PN-EN 60754-1 and PN-EN 60754-2: assessing hydrogen halide content as well as acidity and conductivity.
• PN-EN 61034-2: evaluating smoke density.

Core colours and terminal marking

Core colours and terminal markings are covered by different standards: The colours of cores in cables, wires, and flexible cords are governed by the PN-HD 308 S2:2007 standard. According to this specification, the protective conductor (PE) must be green-yellow, the neutral conductor (N) must be light blue, and the phase conductors are identified by brown, black, and grey colours.

A common error in technical documentation is the conflation of conductor colours with terminal markings. While the physical colour is defined by PN-HD 308 S2:2007, the identification of device terminals and conductor ends is regulated by a different standard, PN-EN IEC 60445:2022-04. This latter standard specifies the use of the letters L1, L2, L3, N, and PE for terminal marking. Because these two documents serve different scopes—one addressing the colour of the product itself and the other the identification of connection points—they must be applied independently and correctly in any professional design or installation.

Selecting the cross-section and common mistakes

The selection of conductor cross-sections and their installation must strictly adhere to the guidelines provided in PN-HD 60364-5-52:2011, including the A12:2023-04 amendment. This standard dictates how to determine long-term current carrying capacity (ampacity) based on various installation methods. A critical technical factor is that ampacity is not determined by the cross-section alone; the method of installation plays a decisive role. For instance, a cable installed in a conduit or a bundle dissipates heat less efficiently than a cable laid in free air. Consequently, the permissible current for cables in enclosed environments is lower than for those in open air.

When designing a circuit, engineers must look beyond simple current carrying capacity. The cross-section must also be selected to ensure that the voltage drop over the entire length of the circuit remains within permissible limits. Selecting a conductor based solely on ampacity without considering voltage drop can lead to operational issues in long runs.

In the Polish market, technical-building regulations impose specific material requirements for conductors. For conductors with a cross-section up to and including 10 mm², the use of copper is mandatory. Aluminum conductors are only permitted for cross-sections starting from 16 mm².

One of the most fundamental mistakes in circuit design is selecting overcurrent protection based on the power of the load rather than the cable itself. To ensure proper protection against overloading, the overcurrent protection device must be selected to protect the conductor. The primary goal is to prevent the cable from reaching temperatures that compromise its insulation and structural integrity.

Cable manufacturers present on the Polish market

When sourcing electrical components, it is critical to distinguish between the manufacturer and the product designation. For instance, names such as Tele-Fonika Kable, NKT, Bitner, Technokabel, Elektrokabel, Eltrim Kable, or Elpar, as well as international suppliers like Helukabel and Lapp, represent the producers of the goods. In contrast, designations such as YDY or YKY refer to the specific type of cable itself.

To ensure correct selection and compliance during purchase, a professional must verify three details:

• The specific cable type and its cross-section.
• The fire reaction class as declared in the Declaration of Performance (DoP).
• Compliance with the relevant product standard.