All you need to know about residential electrical cable

The different types of residential electrical cable

H07VU cable: the classic rigid conductor

H07VU cable is the most commonly used electrical wire in French domestic installations. This is a rigid conductor with a solid copper core surrounded by an insulating PVC sheath. This standardized designation reveals its characteristics: H07 indicates a rated voltage of 450/750V, V means PVC insulation, and U designates a rigid single-wire conductor.

This type of cable is available in several cross-sections, from 1.5 mm² for lighting to 16 mm² for high-power circuits. Its rigidity makes it easy to pass through technical ducts and ensures excellent mechanical resistance in flush-mounted installations. H07VU cable comes in a range of standardized colors: blue for neutral, green/yellow for ground, and various shades (red, black, orange) for the phases.

H07VK cable: the flexible wire for connections

Unlike H07VU, H07VK cable has a multi-stranded core, making it extremely flexible. This flexibility makes it ideal for connections in electrical panels, junction boxes and all locations requiring frequent handling. The K in the designation stands for "Klasse 5", a German classification indicating a flexible conductor.

Professional electricians prefer this type of cable for final connections, as its flexibility greatly simplifies work in confined spaces such as flush-mounted boxes. It also withstands vibrations better than its rigid counterpart, making it ideal for mobile installations or those subject to mechanical stress.

R2V cable: for underground installations

R2V cable (also known as U-1000 R2V) is the preferred solution for outdoor and underground installations. Its multi-layer construction ensures optimum protection: copper conductors, PVC insulation (V), PVC filler (2), and PVC outer sheath (R for round). This triple protection guarantees exceptional resistance to moisture, impact and chemical aggression.

Available in multipolar versions (2 to 5 conductors), R2V is mainly used to supply outbuildings and garden sheds, or to connect the meter to the main switchboard. Its cross-section generally varies from 3x1.5 mm² to 3x25 mm², depending on the power to be carried and the length of the cable.

XVB cable: a versatile alternative

The XVB cable shares many similarities with the R2V, but is distinguished by its slightly different construction. The X indicates cross-linked polyethylene (XLPE) insulation, offering better thermal resistance than standard PVC. This feature enables the XVB to withstand higher temperatures, up to 90°C in normal operation.

Particularly well-suited to industrial and tertiary installations, the XVB can also be used in homes for high-power circuits such as electric kitchens or charging stations for electric vehicles. Its greater flexibility than R2V makes installation easier, especially in difficult passages.

NF C 15-100 standard and cable cross-sections

Minimum cross-sections by circuit type

The French standard NF C 15-100 imposes minimum cross-sections for electrical cables to guarantee the safety of residential installations. These requirements vary according to the use of the circuit and the power of the devices supplied.

For lighting circuits, a 1.5 mm² cross-section cable is sufficient, protected by a maximum 16A circuit breaker. This size allows up to 8 light points to be supplied per circuit. Conventional sockets require a 2.5 mm² cross-section protected by a 20A circuit breaker, allowing a maximum of 12 sockets per copper conductor circuit.

Specialized circuits require larger cross-sections: 2.5 mm² minimum for household appliances such as washing machines or dishwashers, and 6 mm² for an electric hob rated at over 4600W. The electric heating circuit requires a cross-section calculated according to the total power, generally 2.5 mm² for 4500W maximum.

Cross-section calculation based on power and length

Over and above the minimum cross-sections required by regulations, the sizing of electrical cables must take into account the maximum permissible voltage drop (3% for lighting, 5% for other uses). This voltage drop increases in proportion to the length of the cable and the current carried.

For a 20A circuit (approx. 4600W) over a length of 30 meters, a cross-section of 4 mm² becomes necessary to comply with the 5% voltage drop limit, even though the regulatory minimum cross-section would be 2.5 mm². This precaution ensures correct operation of the devices and prevents excessive heating of the conductor.

Online charts and calculators can be used to determine the exact cross-section required, depending on power, length and type of installation (single-phase or three-phase). Professional electricians systematically use these tools to optimize their installations.

Choosing the right cable for the right application

In-wall installation

For electrical installation in walls and partitions, rigid H07VU cable is the ideal choice. Its rigidity facilitates passage through ICTA (Insolant Cintrable Transversalement Annelé) sheaths and holds conductors perfectly in place. The use of technical sheaths protects the cable from mechanical damage and enables it to be replaced at a later date without the need for demolition.

The color of the ducts is also standardized: red ducts are used for high-current circuits (sockets, lighting), while green ducts are reserved for low-current circuits (telephone, internet, alarm). This chromatic distinction considerably simplifies maintenance and future system upgrades.

Surface-mounted wiring and trunking

Exposed installations, common in renovations of older buildings, can use H07VU cable in plastic trunking or moldings. However, some professionals prefer H07VK flexible cable for its ease of handling when positioning in exposed installation accessories.

R2V or XVB cable can also be surface-mounted, offering additional protection thanks to its double sheathing. This solution is particularly useful in garages, cellars or equipment rooms, where the risk of mechanical impact is higher.

Outdoor and underground connections

Any electrical connection exposed to the elements or buried in the ground must use a cable adapted to these environmental constraints. R2V cable is the benchmark for these applications, and can be laid underground at a depth of at least 60 cm, and up to 80 cm under driveways.

A red warning grid must be placed 20 cm above the cable to indicate its presence during future earthworks. For wall or slab penetrations, a protective sleeve (red TPC) provides additional mechanical protection.

For overhead cables between two buildings, R2V cable can be used if supported by a suspension cable, but U-1000 RVFV cable (with integrated suspension wire) offers a more professional and durable solution.

Understanding electrical cable markings

The meaning of standardized codes

Each electrical cable carries a standardized marking that reveals its technical characteristics. Let's take the example of a cable marked "H07V-U 1.5 mm² NF":

• H: cable harmonized to European standards
• 07: rated voltage 450/750V
• V: PVC insulation
• U: single-wire conductor (rigid)
• 1.5 mm²: conductor cross-section
• NF: compliant with French standards

This standardized coding makes it possible to immediately identify the cable's properties and verify its suitability for its intended use. A R2V 3G2.5 mm² cable is a rigid PVC-insulated cable with 3 conductors (phase, neutral, earth - the G standing for "with earth") of 2.5 mm² cross-section.

Certifications and quality labels

The presence of the NF or NF USE mark guarantees that the cable has undergone rigorous compliance testing. These certifications attest to the quality of the copper used, the strength of the insulation and compliance with dimensional tolerances. A certified cable generally costs a little more, but offers incomparable reliability and safety.

Other markings may appear: HAR (Harmonisation Agreement Regulations) for products complying with European agreements, or references to the standard number such as "EN 50525-2-31" for an H07V-U. The presence of the manufacturer's name and production date also enables product traceability.

Good installation practices

Cable preparation and stripping

Clean, precise stripping of the electrical cable is essential to the quality of the connections. Professionals use automatic cable strippers that guarantee removal of the insulating sheath without damaging the conductive copper core. For multi-stranded cables (H07VK), the use of ferrules is essential to prevent the strands from dispersing in the connection terminals.

The stripping length must correspond exactly to the depth of the terminal: too short and there's a risk of pinching the insulation instead of the conductor; too long and there's a risk of exposing bare parts outside the terminal. A general rule of thumb is to strip 12 to 15 mm for connections in modular switchgear.

Respecting color codes

Standardizing driver colors is not just an aesthetic issue: it's a fundamental safety requirement. The protective conductor (earth) must be green and yellow, and this color is reserved exclusively for this purpose. The neutral conductor must be light blue.

For phase conductors, several colors are permitted: black, brown, red, orange, purple, gray. In single-phase, brown or black are traditionally used for the phase. In three-phase, a chromatic convention helps identify the three phases (black, brown, gray, for example), although this is not strictly regulated.

Mechanical cable protection

Even in flush-mounted installations, cables must be protected against mechanical damage. ICTA sheaths with suitable diameters (16 mm for 3 conductors in 1.5 mm², 20 mm for 3 conductors in 2.5 mm²) provide this protection, while also facilitating cable pulling. A specific lubricant can be used for long passages or passages with several bends.

In exposed areas (garages, cellars, equipment rooms), cables must be run in rigid IRL (Insolant Rigide Lisse) conduits or metal cable trays. The minimum installation height for sockets (5 cm from the finished floor) and the required spacing between high and low voltage (3 cm minimum) also contribute to the durability of the installation.

Safety and maintenance of electrical cables

Risks associated with unsuitable cables

Using a cable with a cross-section insufficient for the power being conveyed will cause the conductor to overheat. This rise in temperature gradually degrades the PVC insulation, causing it to harden, crack and eventually lose its dielectric properties. This phenomenon is one of the main causes of electrical fires in the home.

A mechanically damaged cable (crushing, partial cutting, excessive bending) also presents a major hazard. Local resistance increases at the point of deterioration, creating a hot spot that can trigger a fire. Hence the importance of systematically protecting cables in suitable conduits, and regularly checking the condition of the installation.

Inspection and preventive maintenance

A residential electrical installation should be visually inspected annually by the owner or occupant. This basic check consists of verifying that there are no traces of overheating on the sockets (discoloration, burnt smell), that the cables are in good condition and that there are no unwanted circuit breakers indicating a fault.

A full electrical diagnosis by a qualified professional is still recommended every 10 years, and becomes mandatory when selling a home over 15 years old. This diagnosis identifies outdated installations, cables unsuited to current uses (increased power requirements with modern equipment) and non-compliance with standard NF C 15-100.

Evolving electricity needs

Homes built 30 or 40 years ago often have installations that are undersized for today's needs. The proliferation of electrical appliances (computers, televisions, high-performance household appliances) and the emergence of new uses (charging electric vehicles, heat pumps) sometimes require a complete wiring upgrade.

This may mean replacing 1.5 mm² cables with 2.5 mm² on socket circuits, or adding specialized circuits for power-hungry equipment. Anticipating these needs when renovating, by choosing cross-sections slightly larger than the bare minimum, is a wise investment for the future.

Conclusion

Electrical wiring is the backbone of any safe, high-performance residential installation. Understanding the different types available (H07VU, H07VK, R2V, XVB), complying with the minimum cross-sections imposed by the NF C 15-100 standard, and choosing the right cable for each application will ensure the reliability and safety of your electrical installation for many years to come.

Whether you're planning a new build, a complete renovation or just some partial work, the careful selection of electrical cables should never be overlooked. Correct sizing, taking into account power, length and installation conditions, prevents the risk of overheating, optimizes the performance of your equipment and ensures regulatory compliance.

For your electrical installation projects, always opt for NF-certified cables, and don't hesitate to consult a professional electrician for complex installations or when in doubt about the appropriate cross-section. The electrical safety of your home deserves this investment in quality materials and technical expertise.