On Sun, Jul 24, 2022 at 04:28 AM, Mike Gidley wrote:
I was told that the Brown Blue and Green with a yellow stripe was changed because of the Red /Green colourblindness. I dont think Black was part of the change. And green was always earth.
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As I recall the change was made because of the many different and often dangerously contradictory colour codes around the world. The colours arrived at were what was left when all the contradictions were deleted. The use of brown and blue for DC supplies is a major mistake and will inevitably lead to someone connecting a low voltage DC motor to the mains supply, 240 V 50 Hz around here. You may say no-one would be that daft, but I know someone who wired the power inlet of his radio, clearly labelled 6 V DC, to the mains and was most surprised when it all went BANG.
A generally accepted convention is black for 0 V, red for positive, and blue for negative, if you have a split supply. However, my German built motorbikes use the DIN standard for vehicles (very possibly superseded by now) is brown for 0 V and red for +12 V. Other colours including green and yellow (but not Green/Yellow) and many bi-colour wires are used for different wires around the vehicle. The colours for wiring industrial machines, according to the international standard, is black for power supplies, regardless of voltage, AC or DC, or polarity, red for AC control signals, again without regard to voltage, and blue for DC control signals, also regardless of voltage. There are a few other uses of colour, and the colours are not mandatory, but Green/Yellow is strictly reserved for safety earthing, and all Green/Yellow wires are to be earthed.
The colours used on the motor in question indicate the manufacturer has given no thought to safety and just used a commonly available cheap cable. I would never use the colours for mains wiring on anything not intended to be plugged into the mains.
Anyway, in terms of the motor in question, the polarity does not depend on the wire colours, but on which way you want the motor to rotate. If the motor was being used in both forward and reverse the colours would have little meaning, at least in a one off installation.
