Wire colour convention

[Vikash]

Looking to buy some wire but how many colours is ideal? Is there a convention?

AC mains:
-------------
Live: brown
Neutral: blue
Ground: green-yellow

AC secondaries:
Live: ?
Neutral: ?

DC low voltage:
Positive: ?
Negative: ?
Ground: ?

 

[JonSnell Electronic]

Secondaries, there is no live or neutral as they are isolated from mains.
Usual convention is yellow for both.
Positive DC Red
Negative DC Black
Ov / Ground Green

 

[MarcelvdG]

Down here negative DC blue, positive DC red and 0 V black is more usual.

 

[nigelwright7557]

I tend to use 13 amp mains wire for the secondaries.
Wires from bridge rectifier.
Blue = B-
Green = zero volts
Brown = B+

Wires to bridge rectifier can be any.

 

[DF96]

You can get by with about 6 colours, but 10 is better. I use red for main +, black for main -, green 0V and other colours for other voltage rails and DC signals and uncritical AC signals. Critical AC signals are usually screened/shielded.

 

[PRR]

Looking to buy some wire but how many colours is ideal?...

For real chassis clarity, 10 colors is a start, but more can be useful. (Peel your car wires out. Most are at least one stripe on body color; 100 potential codes.)

AND for doing all types of electronics you want every-other common gauge between #16 and #26: four or five gauges.

There are uses for both solid and stranded.

So now I have you buying 200++ spools. The Red and Black #18 and #22 will run out in a month, the pink/purple #28 will go to your heirs when you leave this world.

OTOH, some aircraft are all-White wire. Very confusing, but resists fire.

You can never have too much Red, Black, White, Green, and maybe Blue.

One big gauge and one small gauge will cover 90+% of needs.

 

[PRR]

...Is there a convention?

Many.

AC mains:
Live: brown
Neutral: blue
Ground: green-yellow

AC secondaries:
Live: ?
Neutral: ?

DC low voltage:
Positive: ?
Negative: ?
Ground: ?

Are you actually wiring MAINS? Or winding transformers? Inside a chassis, we normally use the wire on the line-cord and transformer we bought. Jumpers for IEC inlet fuse switch can generally be harvested from excess (spare line cords are cheaper than buying line-grade wire).

BTW: brown/blue is now standard in most of the world, but older UK is different, and US/Can runs Black/White or even Black/Black (in older chassis and transformers or in very-very old wall-work).

PT to rectifier should usually be short so will often use the PT's own wire.

 

[PRR]

Codes aimed at "big exposed" DC systems (solar-power etc):
DC Power Circuit Wiring Color Codes – Label ID Systems Blog

(US) "Military" colors (probably obsolete):
Wire Insulation, Application Color Code, Cable Color Codes

Guitar-amp trends and observations:
Color Codes for DIY amp wiring? - AMPAGE Archive
Internal Wiring

Wikipedia:
Electronic color code - Wikipedia