how to label a wire in control panel

[Winklehoffen]

Good god people! Please, please, pleeeeeease put the same number on both ends of the wire and - as Joshua said - terminals are just an extension of the wire. It is the quickest way of finding where a single wire terminates. Wire numbers should identify the wire, not necessarily the device it is connected to.

Using IO numbering is good but is not really any more effective than having a decent, easy to follow numbering system and falls over when you have multiple devices in an IO feed (e.g. 2 switches in series turning on an input).

Never rely on numbering based on drawings/schematics. More often than not the drawings are either buried in some managers office never to be located until some future archaeological expedition uncovers them, covered in oil and grease and therefore unreadable, not current due to modifications and changes in the past, or just downright lost. If your numbering system relies completely on the schematics then it is inherently flawed.

The best numbering system you can have is a logical sequential flow. Use the same number on both ends of the wire (and terminals). Use sequential numbering through a circuit (e.g. 1 to the stop button, 2 to the start button, 3 to the coil). Identify particular types of wiring with a prefix (e.g. different voltages have different prefixes, you could even use a prefix to identify a wire as a PLC input or output).

From what I have read on this forum, a lot of people seem to work in a happy utopia where drawings are readily available and constantly updated. In my 20 years of fault finding experience I have found this is very rarely the case.

There is not really any decent standard for panel wiring but please think of the poor sparky who, twenty years from now, has to follow each individual wire from point to point to figure out which contact has caked up with dust and is holding up production and costing the client thousands of dollars per minute (but making the sparky money, I guess).

P.S. The more important thing is that you do wire your labels. Anything will do really (as long as it is the same both ends). There's nothing worse than opening up a 4 meter long cabinet full of relays and contactors to find no labels on the wires.

 

[Paullys50]

Why you would label a wire differently on either ends is beyond me. So, label both ends the same!

When it comes to wiring terminated to PLC IO points, I much prefer a system based on the physical layout of the machine/system. Independent of line numbers, independent of device tags (I've seen PS-123 get re-labeled by a plant after install to match some tagging standard they came up with).

I push for a Chassis/Rack/Slot/IO Point system, similar to I1:0/0 but more versatile. Example: C1R01S00/00 would be PLC1, IO Rack 1, slot 0 of the remote IO rack, point 0 of module 0. Keeps the wire label manageable, creates a unique number which I can use in the PLC hardware tree so it's easier to correlate physical IO with what is seen in the software. If we ran into a situation where two devics where in series to an input, it would simply become C1R01S00/00-1, C1R01S00/00-2..etc. It's a little cryptic but as along as the chassis and racks are labeled according, it's pretty simple to figure out.

The chassis number is unique to each PLC in the system, each rack number is unquie to each rack in the system. So it's fairly scalable if you plan correctly.

 

[Outrage]

Why you would label a wire differently on either ends is beyond me. So, label both ends the same!

When it comes to wiring terminated to PLC IO points, I much prefer a system based on the physical layout of the machine/system. Independent of line numbers, independent of device tags (I've seen PS-123 get re-labeled by a plant after install to match some tagging standard they came up with).

I push for a Chassis/Rack/Slot/IO Point system, similar to I1:0/0 but more versatile. Example: C1R01S00/00 would be PLC1, IO Rack 1, slot 0 of the remote IO rack, point 0 of module 0. Keeps the wire label manageable, creates a unique number which I can use in the PLC hardware tree so it's easier to correlate physical IO with what is seen in the software. If we ran into a situation where two devics where in series to an input, it would simply become C1R01S00/00-1, C1R01S00/00-2..etc. It's a little cryptic but as along as the chassis and racks are labeled according, it's pretty simple to figure out.

The chassis number is unique to each PLC in the system, each rack number is unquie to each rack in the system. So it's fairly scalable if you plan correctly.

Hi Pauly,

I've only been forced to do the different numbers on each end thing once, which was for a French company with their standard. In that case the wire numbers on each end reflected the terminals to which the wire was connected:

i.e. PS301-A1 - TB1-1

This is power supply 1 on page 3, terminal A1 to Terminal Block 1 Terminal 1.

It was an absolute farce, I tried and failed to get them to change their standard to no avail. The panel would be impossible to fault find without the drawings. Their justification was that they could rip all of the wires out and put them back in with no drawings, for what purpose I have no idea....

Regarding numbering I find that a panel often has more than a PLC in there, so a generic numbering system which is not specific to any type of component suits me better.

Cheers, Lee

Cheers,

Lee

 

[Outrage]

Lee,

I also use the same wire number at both ends until it switches potential state or is a switchable contact but also add a letter suffix so you can definitively determine where the wire is going (with the aid of the print...) All nodes have at least one wire with the "A" suffix and the neutral/ common return rung frequently get a two letter suffix (Z -> AA ... AZ ->BA). Also avoid "Letter Numbers" such as I = 1 (one) and O = 0 (zero). Terminal blocks keep the same node number so a wire that is 234 on a terminal in one panel has the same number when it gets to the next panel or even in the same panel, such as the common return leg terminals.

Jumping between panels is handled by prefixing every component with what enclosure it's in: 22CR01 is control relay #1 in enclosure #22. You can then use 14CR01 when it enters panel #14 to an interposing relay. I will change the CR to another mnemonic, usually KY or KP depending whether it's an input or an output. This makes it easier to keep the "relay" unique in the bill of material (Did you mean the small CR01 in #22 or the large relay CR01 in #14?)

I don't worry about the sheet number/ line number thing, my electrician and I used the "Find" function in AutoCAD to find every occurance of a component. As changes are made to the drawing and more lines are inserted between existing rungs, the wires would need to change which would be a problem during a "remodeling" project.

MikeW

Hi Mike, Yes like the idea of the interposing connections that makes sense and is generally what we do.

We only use the sheet number as prefix, not a line as well as our drawings are generally on A4 format(at most A3) you can't get enough detail on a drawing of that size to make it worthwhile, our Suffixes are just the next available 2 digit number, which means additions are easy per page. We use blocks of pages for different areas leaving several spares for additions where applicable.

Cheers,

Lee

 

[MikeW]

Lee,

We use A3 (11x17) in portrait orientation so a fair amount of detail can be on one drawing (and usually is) so that you can view a lot of wiring without having to find the next page where it continues.

The other thing we do in numbering is to allocate wire numbers based on voltage/ type, such as:
01-99 Motor Voltage , typically 480 VAC
101-199 120VAC
200-499 24VDC
500-599 24VAC
etc.

and each wire number series has it's own color scheme that aids in knowing what you are working with (i.e Asking the new electrician "why are the blue 24VDC wires in the same conduit as the black motor leads?")

MikeW

 

[rQx]

We use the principle of same potential, same number. So several wires can have the same number if it is the same potential.
Common potentials such as power bus will be "L1", "L2", "L3", control voltage "LD1", "LD2".."0V". All other wires will be labelled according to "related item"-"wire", i.e. "23-1" for the 1st wire related to item 23.
We do not use that wirenumbers or any other labelling refers to the physical position in diagrams. In stead all our documentation and component labelling is organised in "items".

We use a similar system, atleast for the power. L1, L2 and L3. If we go through a motor circuit breaker for example we will label the wires on the other side of it with 1L1, 1L2, 1L3. If we continue through a contactor we will label the other side 2L1, 2L2, 2L3 and so on.

For our control voltage we use +F6 (+24VDC from fuse F6) and -F6, for example.

For the terminals we label with the terminal number. Terminal number 32 will simply have the number 32 on both ends and no other wire can have that label.

For the rest of the wires (what is left is wires between components) we label the starting with 01. Same label at both ends of the wire and there can be no other wire with that label.


Also we don't label our smallest cabinets.
Larger cabinets we do label.

 

[seppoalanen]

Draw Circuit diagrams as wired and wire as have drawed.
Use Circuit Diagrams and do not use any labels except: when disconnect wire some reason and, take it off when reconnect.
For instance: Telephone centres have done without labeling 100 years, there are no room for labels and, there are millions wires!

 

[cwal61]

Draw Circuit diagrams as wired and wire as have drawed.
Use Circuit Diagrams and do not use any labels except: when disconnect wire some reason and, take it off when reconnect.
For instance: Telephone centres have done without labeling 100 years, there are no room for labels and, there are millions wires!

that's because they are Color Coded.

Control Panels and Wire Labels are like Dogs. Everyone has there favorite breed but sooner or later someone else comes along and you end up with a MUTT.

 

[Bit_Bucket_07]

Draw Circuit diagrams as wired and wire as have drawed.
Use Circuit Diagrams and do not use any labels except: when disconnect wire some reason and, take it off when reconnect.
For instance: Telephone centres have done without labeling 100 years, there are no room for labels and, there are millions wires!

Construction electricians would love you. I consider terminating control wires without labeling them first a firing offense.

 

[seppoalanen]

that's because they are Color Coded.

Control Panels and Wire Labels are like Dogs. Everyone has there favorite breed but sooner or later someone else comes along and you end up with a MUTT.

In 1976- we has 20 meters (60 feet) of wired locig cubicles (Siemens gate circuit) and all has wired with AWG18 yellow wire without labels.
Telephone peoples have hundreds of black/red cross-connection wires but they don't need labels, they can reed drawings.

 

[FactoryTalktotheHand]

This is kind of a general thought, but I think If you're troubleshooting a system, you really should have a print. I realize that prints aren't always available because not every company has their ducks in a row regarding documentation, but I feel like accommodating that kind of poor business management in system design only further perpetuates and enables those practices. I just don't think it's a good idea to design under the assumption that the customer will lose the prints. Companies SHOULD be keeping schematics on file and readily available. It's pretty important documentation and in situations where prints aren't kept or maintained I'm sure those companies have no problem keeping their accounting books and other important business documentation sorted and filed. So why does something as vital to operations as schematics get to be the exception?

Sequential numbering may be fine with the first iteration of a system, but things will more than likely need to be modified. One of the most annoying things I've had to deal with when adding to a system that has been sequentially numbered is having to comb through a huge set of drawings to figure out what the last number they used was. It makes accidentally putting a duplicate wire/component number out there and causing even more confusion much more likely. If it's all based on sheet/line number, I can be much more confident that when I add something to sheet 7, line 44 there isn't going to be something else out there with the same number.

 

[duckman]

I do wonder how many people answering this question, have had to try and fault find problems at 2am and come across some silly idea about labelling the same wire different numbers at each end. ONLY an engineer could come up with non logical reason for doing it.
Like said in the first few posts ASK the Electrician not the Engineer how it should be done. Closer to catching Lance, Way past PLCman2

 

[Brijm]

Hi guys

a question about how to label a wire in control panel:
one guy told me that we must use same label for two ends of a wire.
if the the two ends of wire on two different drawing, for example, drawing 01, terminal 01 and another end on drawing 02, terminal 02, could we label one end as 01-01, and another end as 02-02, on the drawing, it will show 01-01 linked with 02-02?

Thanks

The end goal is to make the machine work, and to be able to keep it working. Prints are always useful, as are wire numbers. Hopefully, if you lose or one gets destroyed, you can still work on the machine.

For us, wires are labeled the same on both sides, and wires of the same potential are labeled the same. Wire numbers are based on page reference to the prints, then sequential. When crossing page numbers, I always reference the source wire number and then after a device, revert back to page number. It seems that when troubleshooting, you either want to know the source or the destination. I normally prefer the source (It seems that if the machine is broken, and I don't have prints, I know what is not working, not what output is not turning on... and trace back). The most important thing is consistency.

With sequential numbers, I can trace back, along the numbers, until I reach an output device or a substantial wire number change. With this also, all my numbers to an input or from an output are similar. With prints I try to put as much of the logical circuit as possible together, hence wire numbers are together. An input module on the first ladder page 2 will have reference numbers 200 - 218, and all numbers between 200 and 250 will deal in some way with that input module.

If I have a common source, that is going to multiple pages, I reference the wire number and the source, from where they came. I hate (especially on some IEC style prints), where I have sort through 20 pages, just to find the circuit breaker or output, because they reference the page before. I want to be able to trace most of the circuit on one or two pages.

Most of our machines are small, and I can understand on larger machines, with many panels, wanting to know where a group of wires is coming or going to. The problem is that it is difficult to do both well, and be able to work on it without prints. I think that much of this can be accomplished with consistent terminal block grouping. I have seen some large systems, which pull off using a from/to different wire labels, but it require much greater planning (a good systemization) and normally a thorough knowledge of the system before hand or the prints.

My belief is that a decent electrician with little knowledge of the system, and if need be with no prints, should be able to reasonably trace through the system. The biggest problem I've found with the way we do it described above (and it is less of a problem with PLC's) is that with multiple parallel branches it can require a lot of tracing to find if a wire is the source, or another branch.

 

[CGB]

I work at a machine design company as a controls engineer, and I used to wire control panels. I have seen variations from other companies, but they are usually companies from other countries. Anyways, working at 3 different companies we have always used the same wire number on both ends of the wire. If the wire goes from one page to another you just pick the line number from the first page it showed up on, or whichever one makes the most sense. For instance, if my 24vdc circuit starts on page 7 and line 20 then my wire number would be 0720. If I supply a device on page 3 and 10 I will still use 0720. I vary from this style of wire numbering for I/O. When I am working on the machine and I see a sensor, it benefits me to know what I/O point it goes to without having to open the drawing packet. On another note, you might drive your electrician nuts if you start having different labels on different ends of the wire.

This is the method that I like as well, are we are currently in the process of implementing a new wire numbering standard, where there currently isn't one. The problem I'm having with this method of using the sheet and row number is what happens in you want to divide up the system into different drawings for each control panel, and there are wires that connect between the panels. Wire number 0720 in drawing #1 doesn't work for drawing #2 where say said wire connects between the two drawings. Any Ideas for this??

 

[Steve Bailey]

This is an eight year old thread with more than 40 posts. Before replying to CGB you might want to check to make sure someone else hasn't already made the comment you plan to.