Many electricians are aware of that using different color by different usage of wires. Wiring safety codes vary by country by country, but now the IEC is attempting to standardize wiring amongst member countries. In building wiring and for ordinary three phase system of 230/400V, IEC 60446 indicates the color of

phase line as brown, black and grey

and for neutral line as blue

and for protective earth line as green with yellow stripe.

In United States, ordinally in residential area they are served 120/207V in three phases and familiar with color of phase line as black, red and blue and neutral as white and protective earth line as green or bare conductor and for isolated ground as green with yellow stripe. In United States, many big building installed 277/480V as the first service and 120/207V as secondary and the color of the first service phase is denoted as brown, orange and blue and for neutral line as grey color, and in secondary services they uses colors the same as they are using in ordinal residential area.