• Grounded conductor (“neutral”): wires must be white or gray
• Grounding conductor (“ground”): wires must be bare, green, or green/yellow striped
• Orange

The color of the (grounded/neutral conductor is statutorily blue. PEN (Protective/Earth Neutral, combined) conductor, when insulated, shall be marked by one of the following methods:

• Green-and-yellow throughout its length with, in addition, light blue markings at the terminations, or
• Light blue throughout its length with, in addition, green-and-yellow markings at the terminations

http://en.wikipedia.org/wiki/IEC_60446 http://www.allaboutcircuits.com/vol_5/chpt_2/2.html

• black, red and white

• black, red, blue and white

• black, orange, blue and white

• brown, violet, yellow and gray

• brown and white
• brown and blue¹⁾

• brown, purple, yellow, gray
• brown, purple, yellow, blue

• Orange is the only specified ungrounded conductor and marks the “wild leg” of a 120/240 center-tapped neutral delta configuration. For those unfamiliar: In wild leg configuration, the two end phases on the center-tapped winding provide 120 volts to neutral, but on the wild leg you will find nearly 208 volts to the neutral. If you see an orange wire in a panel, alarm bells of caution should go off in your head. You don’t want to wire a 120 VAC outlet across the wild 208 volt phase.