Single-phase (current colours)
Line (L): Brown
The line conductor of a single-phase circuit. Red before the 2004 change
BS 7671 Table 51
Neutral (N): Blue
The neutral conductor. Black before the 2004 change
BS 7671 Table 51
Protective Conductor (Earth): Green-and-Yellow
The circuit protective conductor (earth). Unchanged by the 2004 change
BS 7671 Table 51
Three-phase (current colours)
L1: Brown
First line conductor of a three-phase supply. Red before the 2004 change
BS 7671 Table 51
L2: Black
Second line conductor. Yellow before the 2004 change, and black used to mean neutral
BS 7671 Table 51
L3: Grey
Third line conductor. Blue before the 2004 change
BS 7671 Table 51
Neutral (N): Blue
Three-phase neutral. Black before the 2004 change, and blue used to mean L3
BS 7671 Table 51
Old colours (before 2004)
Old Line (L): Red
Single-phase line in an installation wired to the old colours. Now brown
BS 7671 before Amendment 2:2004
Old Neutral (N): Black
Neutral in the old colours, single- or three-phase. Now blue. Black now means L2
BS 7671 before Amendment 2:2004
Old L1: Red
First line conductor of a three-phase supply in the old colours. Now brown
BS 7671 before Amendment 2:2004
Old L2: Yellow
Second line conductor in the old colours. Now black
BS 7671 before Amendment 2:2004
Old L3: Blue
Third line conductor in the old colours. Now grey. Blue now means neutral
BS 7671 before Amendment 2:2004
Marking on site
Blue Core Sleeved Brown
A blue core used as a line conductor, such as the switch wire in twin-and-earth to a light switch, marked brown at its terminations
BS 7671 Section 514
Bare Earth Sleeved Green-and-Yellow
The bare protective conductor in twin-and-earth cable, sleeved green-and-yellow where it is terminated
BS 7671 Section 514
All 14 at a glance
| Entry | What it means | Group | Standard |
|---|---|---|---|
| Line (L): Brown | The line conductor of a single-phase circuit. Red before the 2004 change | Single-phase (current colours) | BS 7671 Table 51 |
| Neutral (N): Blue | The neutral conductor. Black before the 2004 change | Single-phase (current colours) | BS 7671 Table 51 |
| Protective Conductor (Earth): Green-and-Yellow | The circuit protective conductor (earth). Unchanged by the 2004 change | Single-phase (current colours) | BS 7671 Table 51 |
| L1: Brown | First line conductor of a three-phase supply. Red before the 2004 change | Three-phase (current colours) | BS 7671 Table 51 |
| L2: Black | Second line conductor. Yellow before the 2004 change, and black used to mean neutral | Three-phase (current colours) | BS 7671 Table 51 |
| L3: Grey | Third line conductor. Blue before the 2004 change | Three-phase (current colours) | BS 7671 Table 51 |
| Neutral (N): Blue | Three-phase neutral. Black before the 2004 change, and blue used to mean L3 | Three-phase (current colours) | BS 7671 Table 51 |
| Old Line (L): Red | Single-phase line in an installation wired to the old colours. Now brown | Old colours (before 2004) | BS 7671 before Amendment 2:2004 |
| Old Neutral (N): Black | Neutral in the old colours, single- or three-phase. Now blue. Black now means L2 | Old colours (before 2004) | BS 7671 before Amendment 2:2004 |
| Old L1: Red | First line conductor of a three-phase supply in the old colours. Now brown | Old colours (before 2004) | BS 7671 before Amendment 2:2004 |
| Old L2: Yellow | Second line conductor in the old colours. Now black | Old colours (before 2004) | BS 7671 before Amendment 2:2004 |
| Old L3: Blue | Third line conductor in the old colours. Now grey. Blue now means neutral | Old colours (before 2004) | BS 7671 before Amendment 2:2004 |
| Blue Core Sleeved Brown | A blue core used as a line conductor, such as the switch wire in twin-and-earth to a light switch, marked brown at its terminations | Marking on site | BS 7671 Section 514 |
| Bare Earth Sleeved Green-and-Yellow | The bare protective conductor in twin-and-earth cable, sleeved green-and-yellow where it is terminated | Marking on site | BS 7671 Section 514 |
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