Colour coding

[akis]

Red for V+, Black for V-, but what if you have dual rails, then what colour for the "common" or if the common is still black, then what colour for the -Vee ? Imagine a desktop PSU with normal DC outputs, so red and black connectors, and imagine the PSU also has +/- symmetric outputs for powering quickly op-amp circuits and such. What colour to choose for the "common" or for the negative rail?

[tszaboo]

V+ red, GND black, V- blue.

[akis]

Thank you. Have you ever accidentally used the blue instead of the black (depending on the darkness of the blue they are easy to confuse) ?

[tszaboo]

I blew up stuff every now and then because of wrong or reverse connection. It is part of the job.

[Psi]

Picking wire colors is quite an interesting topic.

Red/black is obvious, but sometimes you get red wire with a black stripe etc..

Or speaker cable where one wire has a stripe, do you make that wire the negative or positive and does the stripe color change that decision?

Or when you're wiring up power, ground and signal to a 3 wire cable that has only blue, orange and white wire. What do you use for what?


i go by the rules
"Solid color wires are classified first based on their color (before any striped wires)"
"Warm colors are positive"
"Cool colors are negative (with the exception of green which is earth or ground)"
"Dark and Neutral colors are grounds" (etc black white or gray)


So for an example, with a 2 wire black cable (one with stripe) The plain black is neg (rule 1) so the black with stripe must be positive.

For voltages i try to stick to the same colors as PC powersupplies
orange for 3.3v
red for 5v
yellow for 12v

Negative rails i usually make blue, aqua or purple

[Alana]

I usually stick to colour ribbon cables so + is red, next to it is blue that goes to ground and next is black that is -
This way i have nice + 0 - connection.
In case i do not use those ribbon cables i stick to what Psi said.