Wire numbering scheme

Discussion in 'General Electronics Chat' started by jmoffat, Jul 24, 2016.

  1. jmoffat

    Thread Starter Member

    Jul 18, 2012
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    I work for a small manufacturing firm and we are redesigning the control electronics to include a PLC, HMI and VFD. The question has come up as how to designate the wires. One school of thought is to give each wire a discreet number. The other school is to number the nodes. Scheme 1 would have each of the wires for example from the power supply positive to the HMI, PLC , Estop relay, etc would have a different number. In scheme 2 the power supply positive wire to each device would have the same number. Is there a better way to do this? What if any is the standard of the industry? Where can I learn about this stuff?

    Jmoffat
     
  2. nsaspook

    AAC Fanatic!

    Aug 27, 2009
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    You can use this as the base document for your system. Your wire ID designator hopefully should have some relationship to the connection points by direct marking or lookup table for a unique ID tag.
     
    Last edited: Jul 24, 2016
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
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    For PLC marking it is normal to use the address of the actual Input/output and as designated in the ladder.
    Max.
     
  4. hp1729

    Well-Known Member

    Nov 23, 2015
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    Are the colors of the wires unique to function? How about numbering the wires according to their color?
    Standard color code. A green wire with a red stripe would be "52".. Maybe follow that with gauge? 52-24 would be a green wire with a red stripe, 24 gauge.
    That way looking at a schematic it is easier to find a physical wire.
     
  5. gerty

    AAC Fanatic!

    Aug 30, 2007
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    Like Max said, and keep the other control wiring in step with what's already there. If you're not using any of the original wiring ,or numbers, start at 1 and keep going.
     
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  6. MaxHeadRoom

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    Also if pursuing wiring control electric/electronics etc, I strongly suggest a copy of NFPA79 for NEC guide lines and current methods, conductor colours, layouts etc.
    Max.
     
  7. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    Here are two schemes we use at my plant:

    First is the wires are numbered and the color of the wire indicates the number. One is brown, two is red, three is orange, and so fourth, just like the resistor color code. Above 10 you need striped wire, and you get to choose what base color means 10. We use white for 10. This scheme is best for small numbers of wires.

    The next scheme all wires are white but get marked with a discrete wire number. As you are marking the number you can include other characteristics such as wire size, termination, whatever. Works very well for very large numbers of wires; wires can be prepared in advance and stored in sorted order for assembly. It helps to have a $$$ laser marker attached to your wire cutting machine (also $$$).
     
  8. MaxHeadRoom

    Expert

    Jul 18, 2013
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    As a reminder, in N.A. , the conductor colour for a conductor that indicates it is live when the local disconnect is off and fed from a separate source has changed and is now Orange in place of yellow to conform to EU standard.
    Max.
     
  9. jmoffat

    Thread Starter Member

    Jul 18, 2012
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    Thanks for the information. I'll read it in detail in the morning and share it with our design engineer.

    Jmoffat
     
  10. MaxHeadRoom

    Expert

    Jul 18, 2013
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    The industry standard for PLC is the I/O address and the position on the rack, not only does it make an I/O wiring device easily identifiable it conforms to the software display of the ladder logic device address itself, usually with the I replaced by X and the O replaced with Y on the display for input and output respectively..

    [​IMG]
    Max.
     
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  11. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
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    The ISA probably has some guidelines and I should have access.

    But, I had to wire a bunch of interconnected panels with (FEP - the red stuff used for fire alarms) wire. So, I put clips on them A-Z, AA-ZZ.
    Each location had a number, like 1,2,3,4. So cables got labels like 1A5, 3Z7. The internal wires to the cable were unlabled.
    So, cable A had a function and went from panel 1 to panel 5.

    In any designed panel, the terminal blocks would terminate near where the wires entered. They would be cross-connected to where they need to go in the box. Much like telco distribution.

    At home, there can be functionality changes to low voltage areas. One day a CAT6 could be telco and another Ethernet.
    In a house, the rooms don't get numbers, but names. 4 CAT6 cables, two colors of jackets.

    One instrument had all white wires, but each wire has a number on it everywhere on it's wire.

    I used tags to take stuff apart so it could be put back together again. e.g. Hoist switch.

    One guy was tasked to move a piece of scientific equipment and so, he used some sort of system with color coded domino like flags.
    The cables were likely BNC or D or some other kind of mult-pin connector, but there were lots of cables.
     
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  12. Marley

    Member

    Apr 4, 2016
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    There are various standards for control panel design. Depends on which country you are in or selling to. Usually covers things such as wire numbering, colours, etc. Remember, standards are only recommendations.

    Unless you are forced by customer requirements, best to go with what works for you. In my opinion, the reason you have wire numbering and colours is so that you can relate the actual wiring to the circuit diagram and documentation.

    What the committees that come up with some of these standards seem to forget is that in the real world, during the equipment's lifetime, circuit diagrams get lost and the original designers move on. Much better, IMHO, that it is possible to open up a control panel, without any documentation and at least get some idea of what's going on. I know - because I have often had to get some machine working, on the factory floor, while lots of operatives are standing around and the company owner putting serious pressure on me!

    So: Use sensible colours like black for 0V, red for +24V. Standard colours for high voltage wires. Number individually all wires so that if wire xxx disappears into a great bundle of wires it can be identified somewhere else. X and Y for PLC connections is good.

    Currently having to design stuff to IEC standard: All wires same colour, wire numbers not allowed!! Even same idents for different components! Totally mad but have to do it.
     
  13. MaxHeadRoom

    Expert

    Jul 18, 2013
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    But also having a conductor colour for conditions as outlined in #8 can be a life saver, I have worked on a few machines where this practice was in place and it is nice to know that something can be live in spite of the main disconnect being Off!
    Max.
     
  14. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
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    Max:

    That was, sort of, what I did in this one system i designed that had panels in different rooms. I would only allow contact closure inputs and outputs. That to me was better than powering a lamp from a power supply located in a panel 150 feet away.

    The input to one of those DIN relays was easy to track.
     
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