Main conductors
| Wire | Color | Purpose |
|---|---|---|
| L | brown | Live (phase). Black and grey are also allowed - any color except blue and green-yellow. |
| N | blue | Neutral. Blue is used for the neutral only. |
| PE | green-yellow | Protective earth. Green-yellow is reserved for PE and nothing else. |
| PEN | green-yellow + blue marks | Combined neutral and protective conductor (TN-C system): green-yellow along its length with blue marks at the ends. |
Phases in a three-phase system
| Wire | Color | Purpose |
|---|---|---|
| L1 | brown | First phase (A). |
| L2 | black | Second phase (B). |
| L3 | grey | Third phase (C). |
| N | blue | Neutral. |
| PE | green-yellow | Protective earth. |
Two colors are strictly reserved
green-yellow is always and only the protective earth PE - it must never be used as a live or neutral. blue is always and only the neutral N. Any remaining color can be used for the live, most often brown or black.
In old wiring, color is no guarantee
Soviet-era buildings often have single-color wires (white or black), the protective conductor may be missing entirely (two-wire system), and the old phase marking (red, yellow, green) clashes with the modern code, where green belongs to earth. Before working, always verify each conductor with a voltage tester or multimeter - never trust color alone.
Important
The marking follows GOST R 50462 / IEC 60446 and the local wiring code. Reference material only - installation and any live work must be done by a qualified electrician, with the supply disconnected and verified dead.