What color are gray and blue

Power cord: what the colors mean

The colors of the power cables keep puzzling. Anyone who wants to connect a luminaire that does not just have to be plugged into the socket is faced with a challenge: Loud power cables come from the ceiling or wall, the colors of which confuse the average craftsman more than they help. What is the significance of these cable colors? We clarify.

Power cord: what the colors mean
Power cord: what the colors mean

Power cable colors reveal the function of a wire

The power cable colors do not fulfill decorative purposes, but follow a Europe-wide regulation. This defines which "cable" - correctly which "line" - has which color. To put it precisely, standardization is not about the cable color, but about the color of the wires. Because in a single power cable, several wires isolated from one another are combined. The respective color of the wire provides information about its function.

The correct coloring of the cable is of the utmost importance, because one core is not the same as one! Our low-voltage network, to which all German households are connected, needs three different types of wires for safe operation.

These are:

  • Outer conductor (L, phase)
    The outer conductor or the phase carries the current to the device (for example the lamp) and is therefore live. The phases L1 to L3 are sheathed in brown, black and gray.
  • Neutral conductor (N, neutral conductor)
    The neutral conductor ensures that the current can flow by directing it from the device back to the power source. It's covered in blue.
  • Grounding (protective conductor, earth or PE for "protected earth")
    The protective conductor ensures that any contact voltage that may occur is routed towards earth. He wears a green and yellow cloak.

In a typical home installation there are three phases L1, L2 and L3. However, only one wire with one of the phases leads from the fuse box to each socket and each lamp connection.

Source of danger: power cable: Note for your own safety

In principle, professional laypeople are not allowed to work on electrical systems.
Strictly speaking, the connection of lights is also included here (regulate the relevant
Regulations such as EN, DIN-VDE, TRBS, DGUV).

In addition to the meaning of the colors, there is a basic knowledge of electrical engineering and electrical installation
necessary. First of all, this includes knowledge of the dangers of electricity. Due to
A lack of specialist knowledge often results in hair-raising and sometimes life-threatening situations
Errors, especially in the private sector.

To avoid this, the technical importance of the ladder must be known 100 percent - this is necessary
a professional understanding of how the network is or can be structured,
Currents flow and can flow (even in the event of a fault). For this, in turn, it takes a
Adequate understanding of the electrotechnical fundamentals.

The editors of DAS HAUS only want to enlighten with this article and explicitly advise laypeople not to do so
from carrying out electrical installations yourself without sufficient knowledge!

Typical colors for power cables in modern households

Normally, there are three wires on a lamp connection that have different colors:

  • Green-yellow: PE / earthing
  • Blue: neutral conductor (N)
  • Black / brown / gray: outer conductor (L)

Power cables with four cores can also be found in apartments. The color assignment is this:

  • Green-yellow: grounding (PE)
  • Blue / gray: neutral conductor (N)
  • Brown: outer conductor (L1)
  • Black: outer conductor (L2)

If there is no grounding, the colors indicate this allocation:

  • Blue: neutral conductor
  • Brown: outer conductor (L1)
  • Black: outer conductor (L2)
  • Gray: also available

Power cable colors mixed up? Detect faulty installations

The meaning of the cable colors listed above only applies to current installations,
where the installer has followed the rules!
When checking the function of the incoming ladder, a faulty installation must also be detected.
Unfortunately, it happens again and again that the power cable colors are incorrect or completely different
have been used. It is not uncommon to find the colors white, red and purple even with switched conductors!
Also the "deadly sin" that the green and yellow conductor was used as a phase,
is unfortunately more common than you think! A two-pole one is approved for checking the absence of voltage
To use voltage tester.
The test must be carried out safely, correctly and without any doubt.

Rules for connecting a lamp

First of all, you should always observe these "rules of electrical safety" as the basis of any trade in electronic installations such as connecting a lamp:

  1. unlock
  2. Secure against being switched on again
  3. Determine the absence of tension
  4. earth and short-circuit
  5. Cover or cordon off neighboring, live parts

You should then be able to guarantee the following:

  • Correct dismantling of the cable
  • Stripping the strands of flexible conductors with a suitable tool
  • Correct handling of stripped conductors in the installation (for example in the event of oxidation or paint residues on the copper conductors)
  • correct length of the conductor and the bare area
  • Connection of the earthing of the lamp with the earthing from the ceiling, neutral conductor with neutral conductor and outer conductor with outer conductor
  • Use of suitable and approved clamps, if necessary, other end sleeves and covers (canopy, lamp outlet box)
  • Strain relief for the luminaire cable
  • Restoration of protection class IP20 or higher in some cases. Direct and indirect contact protection must be guaranteed!

Good to know: The liability and full responsibility rests solely with you if the work is not carried out by a professional.

Stay away from the stove connection!

The situation is somewhat different with the stove. It consumes a lot more energy than a single outer conductor could deliver on its own. That is why all three outer conductors (L) are present at the stove connection, as well as the grounding (PE) and the neutral conductor (N). A total of five wires arrive in the stove connection socket. Attention: This is high-voltage current that only trained specialists are allowed to handle!

  • Yellow-green: grounding (PE)
  • Blue: neutral conductor (N)
  • Brown: outer conductor (L1)
  • Black: outer conductor (L2)
  • Gray: outer conductor (L3)

However, it can also be that the three outer conductors are not brown, black and gray, but all have the same color. It is only important that in all installations according to the current standard, the neutral conductor (N) is blue and the grounding (PE) is yellow-green, but none of the outer conductors (L) has one of these colors.

If you find a five-wire power cable, grounding is not automatically connected. Without grounding, the color distribution is this:

  • Blue: neutral conductor (N)
  • Brown: outer conductor (L1)
  • Black: outer conductor (L2)
  • black
  • Gray

Power cable colors: special cases when renovating old buildings

In old buildings, the color of the lines may differ, as the color conventions have changed over the years. For example, the cable color of the neutral conductor (N) changed from then gray (in installations up to 1974) to light blue to the rich blue that is the standard today. With older installations it can be the case that you come across a three-wire cable, where the division corresponds to this:

  • green-yellow / red: grounding (PE)
  • gray: neutral conductor (N)
  • black / brown / blue: outer conductor (L)

Here it becomes clear why laypeople cannot simply rely on the familiar colors of power cables: The combination of blue outer conductor and gray neutral conductor exactly contradicts the current cable colors!

"Classic zeroing" / missing protective conductor

In the beginning of the electronic installation (until after the 2nd World War and still for GDR prefabricated buildings) there was no protective earthing of the devices in the house installation. For single-phase devices, the cables were therefore two-core with the following colors:

  • gray: neutral conductor (N)
  • brown / black: outer conductor (L)

Here the neutral conductor (N) was used as a protective conductor (PE) at the same time. The combination of PE plus N becomes PEN. Hence the term "classic zeroing" and the problematic bridges in the sockets or lamp outlets. If such a PEN is interrupted in a box terminal, for example, the full, life-threatening voltage of 230V is applied to the earthed housing of a switched-on device (via its internal resistance). For this reason, too, from 1974 onwards, a separate protective conductor (green-yellow) must be routed to the socket / lamp in all new installations.

More about electricity

Conclusion: knowing the colors of the power lines is not enough!

Over the decades and in the course of European harmonization, the rules for color coding the wires have changed several times. Especially in old buildings that were not refurbished later, you often come across power cables with colors that deviate from the scheme described above. Therefore, and because the safety standards have changed, it makes sense to renovate the electrical systems in old buildings.

Anyone who cannot clearly identify the functions must definitely ask a specialist! An electrician can easily determine how the wires are connected by taking measurements. In order to reliably carry out and understand such measurements, extensive knowledge and the appropriate tools are required. Doing your own experiments with a multimeter or a single-pole voltage tester is life-threatening!