What would you bet that "green" was needed for lights of the same? Blue would have brought the system into meltdown.
At one time plain-vanilla tray and pendant cables used green and white in various combinations for conductor identification. The allowance for leaving out green and white in multiconductor assemblies is about 12 years old.
“NEMA WC57-1995/ICEA S-73-532” Table E2 (formerly K2) leaves out green and white from the list. Example at:
http://www.nexans.ca/egy/equip/ultx_tc/tray22.htm http://www.drakausa.com/pdfsTAM/t10TPV.pdf http://www.sns.gov/projectinfo/ics/...0Information/Technical%20Information.pdf page 35 has both “K1” and “K2” charts.
