Color Codes for SCADA Panels


Thread Starter


Can anyone tell me if there are standards for wire colors in SCADA panels? We use yellow or red as 110 and blue or green as 24 Vdc. A new panel did not get done this way, it is all yellow.

matthew hyatt

The panel shop I had doing work for me followed UL wiring color code methods

Black is 110vac hot
white is neutral
green (green / yellow tracer) is ground

blue is 24vdc
white w/ blue tracer is 24vdc return

red is switched hot
red w/ white tracer is switched neutral
yellow is power from another panel or source
yellow w/ white tracer is neutral from another panel or source

signal wiring:
shielded cable -
white is negative &
black is positive
or red is positive &
black is negative

Matthew Hyatt
Technical Consultants
[email protected]


Yes I can tell you that there are no standards.

Typically, I have seen yellow used to represent wires that have voltage present when the main disconnect is turned off, although I doubt that this is standardised, either.

If you want specific colors used for certain signal types, you need to specify this to the machine builder _before_ the system is built. Be prepared to pay more for them to do it your way.

--Joe Jansen

Bob Peterson

There are certainly standards, however, the main one (NFPA79) specifically applies to industrial machinery, something scada panels rarely have much to do with, however the color coding used there is widely applicable across many other applications.

The scada people seem to delight in doing things differently.

Byron Wetzel


Color coding is fine, but over the years in power plants / substations (typical traditional SCADA environments) I have seen a dominance of just gray SIS wire with LABELS. These labels followed panel design drawings with label designations. So, I don't know what kind of yellow wiring you have, but it should make sense if it each wire is labeled per some panel design dwgs. (followed by a Factory Acceptance Test, of course!)...if not, good luck... well, good luck in any case!!