Cabling Colours for digital I/O's.

[darnbar]

Hi guys,

Just wondering what is the most common procedure or preference when wiring Digital inputs and outputs.

Most PLC wiring I've seen has the digital inputs and outputs wired in one colour (red) and the common wired in black.

That's fine for one DI and one DI module.

But looking at one job where there is multiple DI/O modules all the I/O's are wired to connector blocks in the same colour. Although they are labelled, from a fault finding point of view or even to easily distinguish them would it be beneficial to wire the digital inputs in one colour and the digital outputs in another?

Or is it standard practice to wire them in one colour?

 

[boneless]

We wire 24 VDC red and 0 VDC brown. I would not use different colors for the same voltage. But I do not think there are any "rules" saying you can't

We have some clients that want analog signals in an other color (white or orange).

 

[Doug-P]

I've seen the wiring done to match A-B module colors - RED= ac input, ORN=ac output, etc.

 

[James Mcquade]

darnbar,

Each country has its own rules and regulations.

In the USA, we go by NFPA 79, standard handbook for electrical machinery.

In your country, I think you go by the EU regulations, although I am probably wrong.

440 vac - I don't think there is a standard, but many companies have their own.
220 vac - black

110 vac - red - hot white - neutral
24 vac - I cant remember
24 vdc - +vdc blue, com blue with white strip or white with blue stripe.

Interface wiring / alternate power source wiring - orange or yellow only. The rules changed recently and I cant remember.

regards,
james

 

[Paullys50]

We wire 24 VDC red and 0 VDC brown. I would not use different colors for the same voltage. But I do not think there are any "rules" saying you can't

We have some clients that want analog signals in an other color (white or orange).

That's an interesting color combo for 24VDC, never seen that one before here in the states. Everything I have seen/done as been to the tune of James Mcquade's post.

 

[boneless]

Should have said that is for Norway .

 

[Paullys50]

Should have said that is for Norway .

I figured something was up, but your location under you name show's USA/Oklahoma City so

 

[boneless]

Correct . I work for Norwegians from OKC

 

[keshik]

110 vac - red - hot white - neutral
...
24 vdc - +vdc blue, com blue with white strip or white with blue stripe.

Interface wiring / alternate power source wiring - orange or yellow only. The rules changed recently and I cant remember.

This is pretty much the same as I've seen/do.

 

[LadderLogic]

Brown for +24VDC and blue for DC common seems to be a popular option, apparently coming from European practice.

 

[Donnchadh]

Hi

In Europe its 24 volt Dc plus is dark blue and 24 volt dc minus is dark blue

I know it may sound odd to some but that is the ce colours



Donnchadh

 

[keshik]

Hi

In Europe its 24 volt Dc plus is dark blue and 24 volt dc minus is dark blue

I know it may sound odd to some but that is the ce colours



Donnchadh

So they're both dark blue? That is odd...

 

[Onstege]

We have worked out a practice regarding 24vdc which is: input=violet, output=green, positive feed=red, negative feed=black, safety=orange.

 

[Bering C Sparky]

Brown for +24VDC and blue for DC common seems to be a popular option, apparently coming from European practice.

I do see this color combination used on factory pre-whipped sensors and pre-made sensor cabling a lot, (Proximity Switches and such).

Brown = 24vdc+
Blue = 24vdc-
Black = PNP
White = NPN

But I know you are talking about field installed wiring not factory installed.


BCS