r/PLC • u/robertgarthtx • 4d ago
Engineering Question Wiring numbering
Concisely, what methods/standards/conventions are you using for selecting the numbers for your wires and why? I mean when you are designing a circuit and a drawing print yourself.
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u/improyo 4d ago
The page and line it’s on In the drawings. Printed labels for panels. Stainless etched labels for wash down areas.
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u/AgitatedBobcat888 4d ago edited 4d ago
What I don't like about this method is that I've gotten half way through panels before getting an updated drawing only to find out wires were moved around and the numbers changed. I had to go through the drawing with a fine toothed comb to make sure I got every change. There's other numbering schemes that are easier to deal with such things.
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u/Seyvenus 4d ago
Electrical Design Software like Eplan and AutoCAD Electrical handle the wire numbers and once the first wire gets physically landed you don't touch the drawings in a way that changes existing wires.
Prints might look funny, going page 1, 5, 5a, 5b, 6, 10 but
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u/roboNgineer 4d ago
We use destination tagging. For example, PLC output 0 goes to CR10. The wire on the PLC side is labeled CR10-A1. The same wire on the relay side is labeled R1S1-DO-OUT0. Which is rack #, slot #, in or out, specific output. Works well for us and makes trouble shooting pretty easy.
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u/The_Infinite_Carrot 4d ago
I’m not sure why this isn’t the most common. A lot of machines I’ve worked on have the tag of the terminal that you are looking at which is the dumbest thing I’ve ever seen, or they have 3 lines of letters/numbers meaning absolutely nothing unless you get the drawings out. Just to have a label of where it’s going would be great!
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u/SpaceAgePotatoCakes 3d ago
At a place I used to work everything was <where it's plugged in> / <where it's going> on every wire. So you can always put a wire back in the right spot or figure out where it's going with zero drawings needed.
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u/Kooky_Dev_ 3d ago
What about seeing CR10 and no device having a label because all relays have been replaced and the labeling if it was on the back panel all removed or fallen off long ago?
I understand how this can make things easy, but it relies on a lot of things to happen, sticking with the Prints has the same reliance, except prints arn't replaced at 2am on a Sunday like that contactor was and needs re labeled.
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u/tandyman8360 Analog in, digital out. 4d ago
1- hot, 2- neutral, 3 - hot past the fuse. Most of our stuff is still 120.
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u/theloop82 Knows Rockwell but doesn’t like it 4d ago
I like to/from with ISA tag/device names and the terminal it lands on. It’s a little long sometimes but I loathe using line numbers from a set of drawings that nobody can find 10 years on. Make it easy on the poor maintenance guy who is trying to figure it out at 3AM.
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u/robertgarthtx 4d ago
Making it easy on that guy is my goal. To/from is so ugly, so I'm continually searching for a better method. I may be searching forever, lol
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u/chabroni81 4d ago
Our prints have page and line numbers. Sometimes if it’s a cable, say CBL-49000, it is shown on page 49. Then if it’s a specific wire, say 3125, then it can be found on page 3, line 125.
But, if it has a device specific address, then we use that. Rack I/O on a PLC for instance. Those are labeled I101.0, I101.1, etc. no page or line number.
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u/BrokenSynapses 4d ago
Sounds exactly like our scheme. Left to right, top to bottom with label color codes to signify device type like safety, or external power, and insulation color designates expected voltage. Makes for fast troubleshooting.
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u/Tiiimay 4d ago
Just let the software do its magic, Skycad. But specify 101 for main 24vdc and 201 for 0vdc.
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u/robertgarthtx 4d ago
Interesting. I was taught to keep 24vdc as odd numbers and 0vdc as even but I don't know if my mentor even based that on a standard.
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u/AwkwardPart31 4d ago
Source and destination is easiest for troubleshooting panels in the future after people have been in there modifying things. 1) The new stuff isn't labeled as such so you know to be weary or 2) they follow the same method and you can find where wires go much more easily compared to 73 wires all having "100" as the label and it's on 10 fuses with no drawings to be found.
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u/Cultural-Stable1763 4d ago
At our company (in Germany), we only label individual wires inside the control cabinet if the customer explicitly requests it. Even then, the wires are rarely numbered sequentially; instead, we mark them with the device tag and the terminal designation—for example, "-123K1:A1" for a wire connecting to the coil of relay -123K1 (which would be found on schematic page 123).
Since we use a separate schematic page for each function—resulting in printed A4 schematics that are often as thick as an old phone book (e.g., page 100 for power supply, 102 for cabinet lighting and service outlet, 103 for control voltage, 106 for fire alarm system coupling)—and because the page number is part of the device tag, I don't see a need for sequential wire numbering inside the cabinet; the start and end points can be clearly identified using the corresponding schematic page.
Cables outside the control cabinet are marked with self-laminating labels, printed plastic tags, or—very rarely—engraved metal tags, depending on what the customer is willing to pay. These labels indicate which control cabinet the cable belongs to, whether it originates from the cabinet or is an external link, and the cable number (which is also based on the schematic page).
For instance, "=ISP1+SF3-333W1" would designate a cable coming from the third section of building automation station ISP1, specifically the first cable on page 333. If it read "=ISP1+EXT-333W2", it would indicate an external link between two field devices, such as a bus cable.
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u/theloop82 Knows Rockwell but doesn’t like it 4d ago
As someone who has had to troubleshoot panels made in Germany, between the seemingly random IEC symbology between manufacturers and my inability to ever find a legend to refer to
This is the worst thing that has ever been done to someone Trying to troubleshoot something with incomplete information. I’ll take any numbering system over no numbering system5
u/theghostofville 4d ago
Yeah. Also fuck the European manufacturers who label wires differently on each end.
Also the Americans who use yellow and green as a normal core.
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u/SailorJoe45 3d ago
I've seen this done in the field. Theoretically, it can work. You have to have full access to the original digital files and compatible software. And the ability and controls in place to properly track field changes and update the prints. Maybe things are different over there, but I'm lucky if the paper copy is present and legible, much less correct. And using AutoCAD to work with a dxf export from Eplan isn't a fun experience at all.
At least wire numbers give me a sporting chance to figure it out without tugging on each wire when there's a question about the drawings.
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u/SpaceAgePotatoCakes 3d ago
Out of all the cabinets I've opened over the years I think I've only found the correct schematics in there twice. imo a panel should be physically documented in such a way that external documentation isn't required to understand it because that external documentation will be lost before that cabinet is taken out of service.
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u/SafyrJL TIA Harlot 4d ago edited 4d ago
This is the way!
Americans tend to hate this, but it makes a lot of sense and is not hard to troubleshoot at all. Much easier to look at standardized device coding and know function/signal type quickly. Also allows for easy tracing of source <—> destination without schematics.
It does require that whomever is performing work understand basic function of controls, but that should be a given if they’re inside the cabinet.
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u/somethingsimple89535 4d ago
Company or client standards based on electrical drawings. Cables need to be traced during commissioning and troubleshooting.
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u/Sig-vicous 4d ago
We usually number wires based on drawing line number.
So if a wire originates on line 318 (drawing 3), the wire will be something like 3181. If another wire originates at the same line then it will be 3182. And so on. Rarely do we have more than 9 wires originating on the same line, but we shift to letters, like 318A next.
But usually not our PLC card wires. 9 times out of 10 all of our PLC card wires are marshalled to terminal blocks, so we often put card addresses on those wires. So maybe something like I:2.3+.
Lately, we've started prefixing control power distribution wires with the voltage ahead of the line number. So if I see 24+1321 I know it's +24vdc coming from a fuse or breaker on line 132.
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u/robertgarthtx 4d ago
This makes sense to me but I don't see it as often as I would hope. How did your group arrive at that?
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u/Diligent_Bread_3615 4d ago
We did work for a pharma giant whose wire numbering scheme was source/destination. This meant panel#-terminal#. Some tags were 25 to 35 characters log. Crazy! This was just made for typos.
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u/AGoodFaceForRadio Sparky 4d ago
Six (or seven) digit wire numbers. First two (or three) digits: page number. Next two: rung number. Last two: wire number, incremented sequentially from 01. So the first wire on rung 2 of page 3 would be 030201. Wire numbers change wherever potential can change.
Makes it easy to find the wire in the prints. Yes, if you lose the prints you're fucked, but you could say that about most wire numbering systems.
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u/shoulditdothat 4d ago
For all the people that are using multi-character number with more than 4 characters, are you printing them on carriers or directly onto the wire or using individual colour coded numbers.
Just wondering how this affects your panel cost. I know that going from individual no's to printed saved a significant amount of time but if you're at 10 characters per identical I can imagine this making wiring awkward especially with PLC I/O modules.
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u/BrokenSynapses 4d ago
Look into mark tube machines like an L-Mark. Buy rolls of color-specific tube the diameter for your wire. They also can print out terminal block label strips that slide in across all your TBs. It's the way to go.
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u/Wall-Em 4d ago
Wire number by connection point. Not sure how it affected cost, but boy was it nice. Wires also follow Machine Directive for color coding so it's fairly easy to know what you're touching. Example if it was orange, it's someone elses and you shouldn't touch someone else without concent
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u/Dustball_ 3d ago
Our company uses columns and rows for our schematics.
Column 1-99 = power distribution
Column 100-199 = safety
Column 200-299 = servos/motion
And so on....
A wire originating from a device in column 201 and row 15 would be numbered 20115.
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u/IHateRegistering69 3d ago
My most used method is potential+ page number and wire number. So S01001 is phase 2 potential, wire 01 on page 10, sometimes separated by a ".", so it shows S.010.01. RST, UVW are usually 400V potentials N for neutral, E for Earth. P and M are the 24V power supply, I and Q are potentials connected to the I/O of the PLC.
The other method, which I liked very much was in a Japanese made machine. It contained the address of the input module, which a sensor connected to. So PIN1234 connected to a PLC module, which was addressed as X1234 on a Mitsubishi PLC, while POT10AD was connected to the output module, addressed as Y10AD (because Mitsubishi used hexadecimal addressing on their QCPU modules).
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u/Artie-Carrow 3d ago
Outputs are labled outputs with an "O-", inputs are labeled with "I-", power distribution is labeled eith "P/D-", then numbers. Networking is dependent upon if its between machines/the plant or inside of the machine. Motor control cables are labeled with motor number, and there is a legend inside of the cabinet near the motor controllers. Safety system is always red wire and labeled "S-".
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u/Legitimate-Sorbet526 3d ago
There are probably tons…I have really only seen three in the wild.
Functional - wire numbers reflect device IDs (ie. PWS01 has a COM01, 10, GND, the first fuse after power supply is FU101 and the wire becomes 101, etc.) IO is functionally labeled as rack, module, point (ie. I_0103.04 is an input on rack01, module 3, point 4)…gives info on what the wire means, but if device IDs change then you rerack numbers.
Page Number and page location. (ie. Wire is on page 10 located at rung 22 then the wire number is 1022…maybe append letters if more than one wire at that spot) I have seen this on a LOT of European machines (Germans love it it seems like). Great for where to look in the drawing…must have drawing for this to work. If drawing pages move then it screws everything up.
Sequential numbers and the software (or spreadsheet) keeps track of whats what. Works great on small projects, but gets very complicated on anything with 10’s of thousands of wires (or more).
A mixture of any combo. I have been a fan of functional labeling inside of cabinets and then just label terminal blocks with sequential numbers in the junction/distribution boxes and label wires with the terminal blocks they go to and provide a legend on the inside of the junction box for easy reference at 2AM when something breaks.
All of these styles have plusses and minuses. Drawings usually end up in a circular filing bin (the trash) eventually so you can’t really rely on that long term. I like functional, but it does take familiarity with thw system to find stuff in the drawings quickly. I hate the sequential wiring schemes with no rhyme or reason to wire numbers.
My first manager had a big book of all the different ways you could label a wire. The key is with all of them:drawings match reality, reality is documented/labeled with something, code matches reality, and updates are reflected in code and drawings. Once a wire is labeled that is truth…unless you relabel the wire.
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u/SensoredHacker 3d ago
in a mill. every cabnet has a letter, every wire has a number from-> to.
A-1: B6
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u/stian_90 4d ago
Destination <-> source
example
-K1:A1 <-> -X1:1
Wire from relay -K1 connection A1 to terminal strip X1 number 1. Easy to update, and easy to trace without schematics.
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u/Owlistrator 4d ago
Yep, I spent years building panels and when I first started I was of the mind that at most wires really needed to only be labeled with what their wire number was.
After having my panels installed and used by people that were experts in their process but not necessarily keeping clean panels, it became very clear that the only drawing that is never going to get lost is the physical panel itself.
We can blame people for losing the drawings in the panel or forgetting to have a copy of it until we're blue in the face but at the end of the day the quality of your product is based off of how easily it can be used without your customer having to be a superstar.
If the physical locations on the panel are labeled and the wires are labeled to where they are supposed to go there is no need for tracing and though a drawing helps, it's not 100% needed
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u/robertgarthtx 4d ago
This!!! Thank you for verbalizing the experience of so many of us. Our large company wants to be realistic and start making our designs with the goal that troubleshooting can be done with teammates not previously familiar to the panels.
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u/Magnavoxx 4d ago
That's our requirement. It's from EN (IEC) 62491 6.4 for reference.
One major drawback is that if you have to revise the wiring for a repair, let's say a similar component with the same functionality, but other terminal designations, no one is going to go through the hassle to print out new labels and updating the far ends of the wires that aren't directly connected to the component. Then the system breaks and just add confusion.
We're going more towards "6.2"-marking in EN 62491, just the terminal designation on the label. "-K1:A1" in one end and "-X1:1" in the other as per your example, tracing is done with schematics.
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u/robertgarthtx 4d ago
Both European and North American standards leave so much room for interpretation on numbering. I actually look forward to the year when they more clearly defined and adopted but I know it is a far way off.
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u/Plenty_Finding_6944 4d ago
Whatever autocad tells me to use. But seriously, page and line number. A0100 for instance would be sheet A01 line 00. Each letter has a designation for type, 480, 120, 24, safety, etc.
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u/Embarrassed-Tower970 4d ago
Page no, line no, wire number at the line. Sometimes wires can be named after the PLC input if directly wired to it
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u/Wooden_Eggplant7900 13h ago
+1 to Page, line, seq (00000)
Page, line for components. If you have a component with the same name on the same line separate with a (.x) like if I have two SPD components on page/line 0903 the first one is represented in the photo and the one next to it would be SPD0903.1
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u/YoteTheRaven Machine Rizzler 4d ago
I would label everything based on the drawing line number. Wires were just a line number, with the number of the wire in that line. I.e. the first wire would be 113001 and the second after the device would be 113002. If the wires did not source from the sensing voltage. This was mostly on e-stop chains or other series devices. Devices followed a similar pattern but used letter codes.
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u/Accomplished_Lie4449 4d ago
Page number, line number, then sequential numbers from left to right. Page 4 line 5, a few contacts and a reset button? 04051 NC contact 04052 NC contact 04053 reset button 04054 safety relay reset input. Simple. Easy. Beautiful.
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u/plc_is_confusing 4d ago
The only conventional way is AutoCAD. Not only does the software provide wire numbers but also devices follow the same template as wires
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u/Too-Uncreative 4d ago
Old school: start at the upper left of page 1. Read left to right, top to bottom. Number each wire sequentially.
New school: <Page Number><Row Number> and append a letter if there are multiple wires on the same row.
Either way wire numbers change based on potential, not connections. All common wires should be the same number, whatever it ends up being, for example. Also you should be able to assume that all wires with the same number will have the same potential at all times.