What is the standard color coding (wires) for a good panel?

ckchew666

Member
Join Date
Aug 2003
Location
Malaysia
Posts
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Hi,

I don't have much experience in panel, appreciate it if someone can highlight me the standard color for a control panel with PLC control.

As I know:

240V AC - RED/BROWN
Neutral - BLUE
GND - GREEN

24V DC -
COM -

Digital signal Input -
Digital signal output -
Analog Input -
Analog output -
RTD -

etc.....

Is there a chart on this?? Thanks.
 
Hi chew

It does depend on the customer's requirement for the colour coding. But a standard in my company goes like this:

24VDC+/- ->GREY
110VDC- ->BLACK
110+ ->RED
Single-phase AC Live ->RED
Single-Phase AC Neut ->BLACK
Three-Phase R ->RED
Three-Phase Y ->YELLOW
Three-Phase B ->BLUE
Three-Phase N ->BLACK
Ground/Earth ->GREEN/YELLOW
Analog IO, RTU cables uses shield cable, in either 2-wire, or 3 wire where:
3 Wire:
Positive -> Red
Negative -> Black
Neutral/Common -> White/Clear
2 Wire:
Positive ->White/Clear
Negative ->Black

But many companies have different preferences.
I also found a link to some old posts:
http://www.plctalk.net/qanda/search.php?searchid=233341

Hope it helps:beerchug:

regards
Sherine T.
 
jolio ST said:
Hi chew

It does depend on the customer's requirement for the colour coding. But a standard in my company goes like this:

24VDC+/- ->GREY
110VDC- ->BLACK
110+ ->RED
Single-phase AC Live ->RED
Single-Phase AC Neut ->BLACK
Three-Phase R ->RED
Three-Phase Y ->YELLOW
Three-Phase B ->BLUE
Three-Phase N ->BLACK
Ground/Earth ->GREEN/YELLOW
Analog IO, RTU cables uses shield cable, in either 2-wire, or 3 wire where:
3 Wire:
Positive -> Red
Negative -> Black
Neutral/Common -> White/Clear
2 Wire:
Positive ->White/Clear
Negative ->Black

But many companies have different preferences.
I also found a link to some old posts:
http://www.plctalk.net/qanda/search.php?searchid=233341

Hope it helps:beerchug:

regards
Sherine T.

Sherine,

Thx for ur info, but we don't have an international standard or something like tat?

If the AC & DC using the same color coding, will it be dangerous when trouble shooting or during maintenance work?

Thanks.
 
It is a better practice to always use different colors for ac/dc voltages. As a rule of thumb I use red for ac,blue for dc, green for ground,white for neutral.
 
nswu1 said:
It is a better practice to always use different colors for ac/dc voltages. As a rule of thumb I use red for ac,blue for dc, green for ground,white for neutral.

How about AC neutral and DC common? AC & DC must have total 4 different color code, right?
 
In the US the only regulated colors are:

White or Grey = Neutral or grounded current carrying conductor
Green or Green/Yellow stripe = ground
Any other color = current carrying conductor

In most industries the following "standard" is common for control:
Blue = DC
Red = 120 VAC control
Black = Power above 120 VAC, usually with separate color tapes like Red/Blue/Orange for each phase of a three phase power
Yellow = foreign voltage, that is a conductor which is powered by a source outside the panel itself
 
If you are building UL listed panels in the US there are guidelines for the color of all the wires in the panel. We have had companies tell us that they want the panel built with their wiring color code and also want a UL label on the panel. We have had to come back and tell them that we have to use the UL 508 color code or we can't put the UL 508 sticker on the panel. When I was in the SE I never had to build UL panels so it didn't matter, but when I moved to the NW I began working in the water/wastewater field and all the municipalities required UL panels. Also the industrial panels in Washington that I build now require UL.
 
I don't work at a place that has a panel shop now, so I don't have the manual handy. I will stop off this afternoon on the way home and get a copy of it though (I've been meaning to do this for a while now) and post them tomorrow. Maybe today if I get the chance to run over there during lunch (if I get a lunch today!).
 
That's is when labelling, grouping and allocation comes in. The designer who draws will usually put up AC components and wirings to a location and DC components and wirings to another location. Labelling enables the differentiation of AC single-phase from AC three-phase. for DC, cable size and good labelling will distinguish between low DC voltage from high DC voltage.

I've read about the IEC standards thingy, but it still boils down to clear details of where this perticular wire belongs to.

But whatever the situation is, I face a great problem whenever I start comissioning the project that left the factory. The control panels look great in the factory, all new and clean, and tested to work. When it is delivered to site, especially one I'm having a headache now, is on board a vessel due to Brazil. The panels are a MESS!! panels dented, meters cracked, relays demaged, keys missing, wires tampered with, and lock being forced opened. Worse still, the panels were certified IP 65, and some bleeding sub-contractors working on the field wirings just drilled 5 big holes on the base for their cables!:eek: There goes the certification.
 
jtn said:
If you are building UL listed panels in the US there are guidelines for the color of all the wires in the panel. We have had companies tell us that they want the panel built with their wiring color code and also want a UL label on the panel. We have had to come back and tell them that we have to use the UL 508 color code or we can't put the UL 508 sticker on the panel. When I was in the SE I never had to build UL panels so it didn't matter, but when I moved to the NW I began working in the water/wastewater field and all the municipalities required UL panels. Also the industrial panels in Washington that I build now require UL.
We are a UL 508 shop and I've never heard of a UL 508 wire color coding standard.

Generally, we use NFPA 79 as our guide for machine tools which pretty much follows what Tom Jenkins said previously. The only extra color we have adopted is blue w/ white stripe for DC 0V.
 
In the US

UL certification is based on NFPA/NEC code/standards. The new Article 409 in NEC 2005 is the primary authority...note: if you use the latest version of NFPA 79 you will be in accordance.

It should be noted that many do not consider NFPA/NEC an authority BUT it should be noted that OSHA (US government authority) requires compliance using NEC and NFPA 79 and a few other standards the NFPA has developed.

What does this mean? It means that you can build it any way you want BUT if someone does get hurt and OSHA investigates and the machinery does not meet or exceed specifications then the company will have problems and many people could be considered liable.

Certain industries may have exemptions to a point but usually it is because another authority requires more extraneous specifications.

You can never rule out OSHA, or the FDA, in the US. I have seen both close a plant....the FDA actually put chains around the building.
 
i use yellow for internal 24vdc wiring, blue for external wiring..red for 110 white for 110v Neutral, red black blue for 3 phase 208 volt and yellow black and brown for 600v

Didnt get this from a book just used standards that ihad seen before..
 
Tom Jenkins said:
In the US the only regulated colors are:

White or Grey = Neutral or grounded current carrying conductor
Green or Green/Yellow stripe = ground
Any other color = current carrying conductor

In most industries the following "standard" is common for control:
Blue = DC
Red = 120 VAC control
Black = Power above 120 VAC, usually with separate color tapes like Red/Blue/Orange for each phase of a three phase power
Yellow = foreign voltage, that is a conductor which is powered by a source outside the panel itself

That is pretty much what we follow with only one modification(probably adopted after some European standards): brown for DC positive bus (usually +24 VDC)
 

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