Cable Colors and their Specifications

Cables and Wires: Function, Characteristics, and Identification

There are a variety of cables with different colors and characteristics.

The main function of cables and wires is to transport electrical energy from the source to the consumer. They are also used for transmitting signals from measuring instruments, control devices, and regulating devices.

Insulated cables and wires consist of one or more conductors that are insulated from each other and held together by a common sheath.

The insulated cables and wires used in electrical installations must comply with the applicable standards and be appropriately labeled by the manufacturer.

In Germany, for example, cables are marked with an imprint or a colored thread.

Color Coding of Cables and Wires

For cables and wires with up to 5 conductors, the individual conductor insulations are marked by colors. If there are more than 5 conductors, these conductors are executed in black and marked with a printed number.

Insulated cables are manufactured with and without protective conductor. The properties of these installation cables are indicated by so-called abbreviations.

Abbreviation    Meaning of the Abbreviation  A   Conductor B   Lead Sheath C   Shielding F   Flat Cable FF   Fine-stranded</ td> G   Rubber Insulation I   Surface Conductor J   Conductor with Protective Conductor L   Fluorescent Lamp Cable M   Sheathed Cable N   Standardized Cable O   Conductor without Protective Conductor Ö   Oil-resistant PL   Pendant Cable St   Static Shield S   Special Cable T   Cable Harness U   Fireproof Sheathing W   Heat-resistant Cable Y   Plastic Insulation Z   Twin Configuration

Number of Conductors   Cables or Wires with protective conductor wire without protective conductor wire   2         3          3*           4          4*           5       >5       In three-phase circuits, the outer conductors L1, L2, L3 should always be colored brown, black, and gray, respectively.

The following color codes are mandatory:

for the protective conductor (PE): green-yellow,

for the neutral conductor (N): blue,

for the protective conductor with neutral conductor function (PEN): green-yellow,
in addition, the ends of the PEN conductor should be marked with blue.

Some of the most common cables include:

NYM-J 3x1.5mm²:
Standard installation cable for indoor use
Suitable for sockets, lamps, fans
3-core cable with a conductor cross-section of 1.5mm² (single-core)
Colors: Blue (neutral conductor), Black or Brown (phase conductor), Yellow-Green (protective conductor)

NYM-J 5x1.5mm²:
Standard installation cable for indoor use
Suitable for switch-lamp wiring
5-core cable with a conductor cross-section of 1.5mm² (single-core)
Colors: Blue (neutral conductor), Black (phase conductor 1), Brown (phase conductor 2), Gray (phase conductor 3), Yellow-Green (protective conductor)
or: Blue (neutral conductor), Black (phase conductor 1), Black (phase conductor 2), Brown (phase conductor 3), Yellow-Green (protective conductor)

NYM-J 5x2.5mm²:
Standard installation cable for indoor use
Suitable for motors, CEE sockets, electric stoves
5-core cable with a conductor cross-section of 2.5mm² (single-core)
Colors: Blue (neutral conductor), Black (phase conductor 1), Brown (phase conductor 2), Gray (phase conductor 3), Yellow-Green (protective conductor)
or: Blue (neutral conductor), Black (phase conductor 1), Black (phase conductor 2), Brown (phase conductor 3), Yellow-Green (protective conductor)

H07V-K 5g2.5mm²:
Standard installation cable for indoor use
Suitable for motors, CEE sockets, electric stoves
5-core cable with a conductor cross-section of 2.5mm² (finely stranded)
Colors: Blue (neutral conductor), Black (phase conductor 1), Brown (phase conductor 2), Gray (phase conductor 3), Yellow-Green (protective conductor)
or: Blue (neutral conductor), Black (phase conductor 1), Black (phase conductor 2), Brown (phase conductor 3), Yellow-Green (protective conductor)

Rating of fixed installed cables and wires

The current-carrying capacity of fixed installed cables and wires depends mainly on the cross-sectional area of the conductor but can also be influenced by other factors such as ambient temperature. The installation method of the cables and wires has a significant impact on their current-carrying capacity.

Cables and wires that are installed in still air, such as in an installation channel or within thermally insulated walls, have a lower ability to dissipate the heat generated by the current to the surrounding environment. In contrast, cables and wires that are installed in the ground or directly on the wall surface have better heat dissipation.

The current-carrying capacity of cables and wires with good heat dissipation is higher.

A total of nine different installation methods (A1, A2, 81, BZ, C, D, E, F, and G) have been defined to describe the ability of cables and wires to dissipate heat.

Deviant operating conditions

...require an adjusted calculation of the current carrying capacity of cables and conductors. The specified current carrying capacity refers to an ambient temperature of 30 °C. If the actual ambient temperature deviates from this reference value, if more than three conductors are loaded, or if harmonic currents occur, the current carrying capacity must be calculated accordingly.

For deviating ambient temperatures, standards or specific calculation methods can be applied to determine the current carrying capacity. These take into account the influence of temperature on the performance of cables and conductors.

If more than three conductors are loaded, the heat losses and the influence of mutual heating of the conductors on the current carrying capacity must be considered.

Harmonic currents cause additional losses in cables and conductors due to increased harmonic currents. These losses can affect the current carrying capacity and must therefore be taken into account in the calculation.

It is important to consult the specific standards, regulations, or guidelines of your country or region to obtain accurate calculation methods for deviating operating conditions. A qualified electrical engineer can assist you in calculating the current carrying capacity under these conditions.

To protect conductors and cables from excessive heating

...overcurrent protection devices are used. These devices are used to protect conductors and cables from overload and short circuits, as these conditions can lead to increased heating.

Overload currents can occur in fault-free circuits when the consumer load exceeds the rated capacity of the conductors and cables. This can occur, for example, due to excessive current consumption of connected devices or faulty operation. Overcurrent protection devices such as fuses or circuit breakers respond to these overload currents and interrupt the circuit to prevent excessive heating of the conductors and cables.

Short-circuit currents occur when there is a direct short circuit between two energized points. This can be caused, for example, by damaged insulation or faulty connections. Short-circuit protection devices such as circuit breakers or power breakers respond to these short-circuit currents and immediately disconnect the circuit to prevent overheating and damage to the conductors and cables.

These overcurrent protection devices are important safety components in electrical installations and ensure reliable protection of conductors and cables from excessive heating, reducing potential fire hazards and increasing operational safety.

The current carrying capacity of cables and conductors is determined by several important influencing factors:

• Conductor cross-section: The cross-section of the conductor determines the maximum allowable current that the cable or conductor can carry. Larger cross-sections allow for higher current carrying capacity.
  
  
• Number of loaded conductors: When multiple conductors are loaded in a cable or conductor, this affects heat generation and can reduce the current carrying capacity. The mutual heating of the conductors must be taken into account.
  
  
• Conductor insulation: The type and quality of insulation influence heat dissipation and thus the current carrying capacity. Good insulation helps retain heat inside the cable and minimizes its impact on the surroundings.
  
  
• Construction of the cable or conductor: The design of the cable or conductor, including the materials used and the layers, can influence heat dissipation and, therefore, the current carrying capacity.
  
  
• Installation method: The way the cable or conductor is installed has a significant impact on heat dissipation. Different installation methods can have different characteristics in terms of heat dissipation.
  
  
• Ambient temperature: Ambient temperature directly affects heat dissipation. Higher temperatures result in poorer heat diss ipation and can reduce the current carrying capacity.
  
  
• Clustering of cables or conductors: When multiple cables or conductors are installed in close proximity to each other, heat dissipation can be affected, reducing the current carrying capacity.
  
  
• Harmonic currents: The presence of harmonic currents caused by non-linear loads can cause additional losses and heating in cables and conductors. These must be considered when determining the current carrying capacity.
  
  
• Insulation: The type and quality of insulation around the cable or conductor can influence heat dissipation and, therefore, the current carrying capacity.

These influencing factors should be carefully considered when calculating the current carrying capacity of cables and conductors to ensure a safe and reliable electrical installation.

Labeling of cables with printed letter and number abbreviations serves for easier identification of the construction type and purpose of the cable.

Labeling Table: