Answer for UK, Europe and countries running a 50 Hz supply service.
It all depends on which connection you are using. Alternating Current (AC) or Direct Current (DC). In AC there are generally two modes of transmission. Single Phase or Three Phase. In case you don't have 3-phase connection just combine yellow and green.
According to Standard, Green is for the Earth Wire and Red is for the Live wire. Blue or Black is for the Neutral Wire. So best option is to combine the Yellow and Green.
In typical American wiring the black wire on an outlet goes to the gold (copper) screw and the white wire goes to the silver screw. The ground wire goes to the green screw.
The grounded conductor (Neutral) can be white or gray. The grounding conductor can be solid green, Green with a yellow tracer or bare copper.
You can rewire your extension cord by replacing the existing wire with green, black and white wires. In most situations it is safer and cheaper to buy a new extention cord.
Depending on the configuration of the cord cap, the green wire is ground, the white wire is the neutral and red and black wires are the 220 volt source.
On a 110 volt circuit, Black is hot, White is neutral, Green or bare Copper is ground. . Connect Black to the gold screw, White to the silver screw, and bare copper ground to the Green ground screw on the receptacle. On a 220 Volt circuit Black & Red are both hot, each carrying 110 volts for a total of 220. White is Neutral and ground is Green or bare copper.
That will depend on the style and school that you go to. In general the colors are white, yellow, green, brown and black, but there are various grades in between and many have added additional ranks.
Red green yellow blue
Red =Brakes or not used Green/yellow right turn Yellow/brown left turn Black= hot White= ground
Red Yellow Blue Green Purple Black White Gray Orange Brown Pink Alphabetical Order: Black Blue Brown Gray Green Orange Pink Purple Red White Yellow
: Wires colors: : Blue/yellow, red/white, yellow (silver dots), yellow/green, red/yellow, blue/red, green/orange, black (silver dots), white/green, brown/white, green (silver dots), white/red, red/black : primary color/stripes
Red, Blue, Green, Yellow, Orange, Black, White, Brown
red, black, white, blue, yellow, green, brown
White, White-Yellow, Yellow, Yellow-Orange, Orange, Orange-Green, Green, Green-Blue, Blue, Blue-Brown, Brown, Black, Red-White, Red
white orange yellow camo green purple blue brown red red/black black
Red+blue = purple Blue+yellow=green Yellow+red=orange Blue+green=blue-green Green+yellow=light green Red+green=brown Red+white=pink Black+white =gray
white
White, yellow, orange, green, blue, purple, brown, black