(Old thread, but…) The North American continent may not be 100% metric, but there is at least one east-of-the-pond custom catching on. Omaha, NB Public Power District requires installers to “identify the phase conductors per the following colors: 120/208V, 3Ph, 4W: Black, Red, and Blue; or Red, Yellow, and Blue.” Earlier this week, I noticed some new local utility riser poles [transition from overhead to underground 12,470Y/7200V] with open, plainly visible phase designations of R-Y-B.]

There are some test leads that use the RYB{+W} 3ø {4-wire} colors… http://www.arbiter.com/catalog/frames/specs/testleads/815at.jpg
A little harder to explain the application, but these current leads use the same… http://www.arbiter.com/catalog/frames/specs/testleads/811at.jpg