Blue Terminal - 24V or 0V???

Everyone,

this post is off topic but brings up a good safety point.

While it is accepted and its in the code book that green is supposed to be ground, DON'T accept this as being correct !!

I worked on one system that used green wire for 120 volt outputs and no I am not kidding!
I assumed ground and got lit up real fast, triac outputs.
I was not happy, I brought in the safety managers and pointed out this problem and wanted to replace the wiring. they replied, I would have to do the wiring on over a dozen panels ! keep it the way it was!

WHY would you use green for power wiring?
it was the weekend and that's all we had!

So DON'T assume green is ground on any panel, verify first.
I never made that mistake again at that facility.

james


You're lucky..Places I've worked at would have fired you for getting shocked and never think twice about why green was used. haha.
 
About wire colors :

IEC60204-1

black: a.c. and d.c. power circuits;
red: a.c. control circuits;
blue: d.c. control circuits
orange: interlock control circuits supplied from an external power source.
light blue: neutral
yellow with green strips: protective ground

But also I have passed different standards compliance tests and they didn't paid much attention to the colors because we usually use many multiconductor cables with all black and also in other cases that you can not use the ideal color either.

On the other hand they were strict with correct cable numbering and their exact correspondence in the diagrams.
 
I got surprised by a hoist with brakes on motors. 6 conductor cable to motors.

Ground wire was white
240VAC Brake wires were orange and brown
240VAC 3Ø to motor was black, red and GREEN. Yes - Line 3 was Green!

Hoist had 2 motors wired identically.
 
Typically I will do:
Grey = +24
Blue=0v
green,green/yellow = earth
red=120vac
blk=480vac or main power feed, 208 etc.

If dealing with analog ins/outs through a terminal block I'll usually try and differentiate it somehow with a different color, I've used orange before, but usually as someone mentioned that's reserved for control interfaces with another power supply.

However we have lots of equipment that's from all over, and so consistency only goes as far as each machine, or group of machines depending on who built them.
 
Working on a project now that has a very comprehensive scheme of terminal and wire colours.


Red = Digital inputs
Orange = Digital outputs
Grey = Neutral
Green = Ground/shield pass through
Green/Yellow = Ground to DIN rail
Light Blue = Analog positive
Yellow = Analog negative



The panels look very nice, with all of the wires coloured to match the terminals and run neatly up to the corresponding PLC cards and terminated. The spare I/O terminals are also labelled with the corresponding PLC bit address, so it made retrofitting equipment very easy.
 
Mylespetro,

"Red = Digital Inputs / Orange = Digital Outputs"

One question - Regardless of AC or DC?

That would be OK if all AC control voltage.
 
I've seen both.

I think the problem comes in the fact that some manufacturers don't make all colors.

We tried to match terminal = wire color, IE Red = 120 ungrounded, white = 120 grounded, blue = 24vdc grounded, white = 24v grounded, etc but it doesn't always work.

Personally, I just use all grey now, and a different color for machine interlocks. One terminal to stock is much easier.
 

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