how to label a wire in control panel

[NetNathan]

My line referencing starts at 100 on sheet 1 and there are 25 "rungs" to a page.
I use "A" size schematics, makes it easy to copy and keep in a binder.
The first page in the binder (Sheet 0) explains the format of the schematics.

 

[FactoryTalktotheHand]

My line referencing starts at 100 on sheet 1 and there are 25 "rungs" to a page.
I use "A" size schematics, makes it easy to copy and keep in a binder.
The first page in the binder (Sheet 0) explains the format of the schematics.

My last job allowed me to define my own schematic standard. I settled on size A as well, portrait orientation. While they may have been fewer things I could put on a single sheet, like you say it can fit in a binder easily. 11x17 can be pretty unwieldy but that's what a lot of people use for some reason.

 

[Timbert]

I vote for individual wire numbers (the same on both ends). They definitely tend to be the most useful during troubleshooting. Engineering and assembly occur once, troubleshooting will done over the life of the machine. So, who should we make the numbers most useful for?

I've worked with electricians that like to have the terminal labeled on each end. They said, "That way it makes it easy to put back in the right spot when they fall off." To which I say, if your machine has wires falling off the terminals regularly, you got bigger problems than wire numbering schemes.

 

[shawn_75]

Perhaps not a good fit for PLC, but I did some work on a networked video conversion / storage and playout system (think TV broadcast center) that had the location of both ends of the wire printed on the label and a label on both ends. It had rack number, elevation, port number and a plain description when appropriate. That was the cat's meow. Didn't even have to look at a print.

 

[allscott]

Perhaps not a good fit for PLC, but I did some work on a networked video conversion / storage and playout system (think TV broadcast center) that had the location of both ends of the wire printed on the label and a label on both ends. It had rack number, elevation, port number and a plain description when appropriate. That was the cat's meow. Didn't even have to look at a print.

Our senior electrician (and mad man electrical guru) does just that. Wires are labeled from where they came from and what they do. IE:"E-Stop from west op station"

Crude and ridiculously long wire names but easy to troubleshoot. We buy lots of tape for the label maker...

 

[shawn_75]

These were more like this:

R4 17 Port 4
R2 20 VSync

That reads Rack 4, Elevation 17 port 4....Rack 2 elevation 20 VSync port

Most everything was local in a series of 6 racks with some going to far off places in the building. Once you know the naming convention, all was good.

 

[OkiePC]

I do like wire numbers. Panel fires happen. I read a post earlier talking about european equipment with no numbers, only terminal block based prints, which means tracing them from end to end when something craters and melts down a relay base past the ferrules on nine wires and you have to substitute a new contactor with ashes and a sideways cryptic print for reference.

For PLC numbers to be used is fine. Modern HMI and with networked machines can greatly benefit from that, if the Photocell is named I:42/12 and you can see it is blinking on the "screen" or LED as your buddy waves his hand in front of it...you are done tracing that suspect. Using I/O naming strategies that are consistent and concise are great, although I do love the hot rod wiring kit I bought for my jeep with complete names printed every 12 inches. Use a system by which you know right where to look for troubleshooting. If you use special naming privileges for PLC I/O, you should make the PLC reference pages easy to locate in the drawing sets. Keep the I/O drawings together, in order of rack layouts, please don't show the slots out of order/hierarchy. But, if you use sheet and line or row/column references for I/O, that is fine too.

They need to be marked following a system that works regardless of project scale. The system should be consistent, and you should be able to read the tag and quickly be able to find what sheet you need to be looking at that. Don't change the name for terminal blocks. Do show the terminal blocks in the schematic and go ahead and name the terminal points if you want, but make sure that it is indicated as a TB number, not a wire number. I do that following the kiss principle, prefix all terminal block numbers with "TB" then name/number. On the prints it is above the terminal symbol noticeably smaller or italicized to be distinguished from wire numbers. And right below the wires connecting I will include the cable colors if available, as an aid for everyone, again, in the smaller font or unique format. That is for everybody from panel builder to end user to assist with tracing without ripping off panduit covers.

 

[GeoffC]

I always prefer the same number at each end of a wire - That is why it is called a wire number.
I much prefer a tag based system of numbering, eg pressure switch PS001 would have wire number PS001.
The main problem I have with using plc addresses or even sheet numbering as the method for coming up with a wire number is in years to come when the plc is updated or the system is modified (drawings changed), some/most of the wire numbers will then be wrong so trying to fault find will involve looking for wires on drawing that don't exist or plc addresses that don't make sense.
A device and its tagname don't change but over time its use in a system may. Also if you use tag based plc programming then the wire number can guide you straight to the relevant section of code in the program

 

[OkiePC]

If you are worried about years from now after rewiring, that you won't properly relabel the wires, then I can live with that fault by using sheet and line for both wires and for device numbers. PS123 is a great name for Pressure Switch found on line 123 of the prints, but the wires would just be numbers, perhaps 1231 from the fuse, FU123, on line 123, leading into the switch, and wire number 1234 coming from it to the coils of relays CR123 and CR124 on a parallel branch. So in that system, the name or wire number leads you to line 123 of the prints where you can see the whole circuit.

 

[LadderLogic]

So in that system, the name or wire number leads you to line 123 of the prints where you can see the whole circuit.

There are two problems with that system though. First, in larger projects the wire numbers may easily become way too long for reasonable maintenance. Second, it assumes that as the projects develops or getting updated, the numbering of the sheets does not change - which is not always true.

It is very convenient to have the wire numbers, the component tags and the cross-references combined (which is what it is). However, with modern design systems like EPlan, ACADE nad others, the point becomes moot since the cross-refs ("where used") are automatically tracked and can easily be printed next to the components if needed.

 

[Bit_Bucket_07]

My problem with this is that using the wire number to reference a PLC address doesn't really help anybody but you, and it only helps you in a very minimal way, but it causes a lot of wasted time on the other end. Especially since in your particular scheme you don't have anything in the formatting that differentiates an address-based wire number from a schematic line number-based wire number. It may be obvious to you, but some guy in the field is going to open a box and see a wire labeled "2015." Is it an I/O address or is it a device on sheet 20, line 15? Even if he has the schematics, it's going to take some time to hash that out. If the numbering were consistent and always referencing a line number, it wouldn't matter. All he'd have to do is find that line number in the schematic. It's only a very minimal inconvenience to the engineer/programmer, who--if he or she is worth his/her salt--will have a copy of the schematics on hand. In the field, what PLC address a wire goes to is of very little importance.

Now that I'm thinking about it, it's strange that PLCs are singled out as something "special" as far as wire numbers are concerned. No other control devices change the wiring number scheme like that. It's strange.

There are legitimate reasons for using wire numbers associated with physical I/O points on the PLC. In the first place, a PLC's I/O System is inherently an end point for wiring. There will never be any devices downstream of an I/O termination point -- only logic exists in that realm. You're going to have to specify the physical I/O point on your schematic anyway. Why not let that terminal point serve as the wire number for that particular wire, even if you do implement line numbers for all other wire numbers?

I see a difference of design priorities between an OEM system and a custom control system. I've built many control systems for clients who make major changes in their plant configurations from time to time, whether to produce a unique product for a new client or to enhance the operation of an existing system. I've seen many control systems re-purposed in this manner. When that happens, the original schematics are pretty much thrown out the window.

It is easier and less confusing to re-purpose an existing PLC based control system if the wire numbers aren't all tied to an old, obsolete schematic.

 

[Outrage]

Hi,

Same number both ends, first two digits are originating page number second two digits are incremented per wire. The wire number stays the same until it passes through a device that switches or alters the characteristics of the potential. i.e. wires passing through terminals stay the same whereas wires passing through a relay contact change. This keeps all wire numbers to four digits generally, unless the panel requires 100+ drawings in which case I increase the page number prefix to 3 digits throughout the set.

The quandary I find is what to do with the interposing signal wiring between 2 panels, any suggestions?

Cheers,

Lee

 

[JesperMP]

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".

 

[joshua_smith123]

As an electrician, i will say that if a wire is not numbered the same at each end, i will be extremely unhappy with whoever designed the numbering system. It is extremely common for drawings to go missing, or designs to be altered over time, and it is much easier to fault find without drawings if the labelling is basic and easy to follow.
A very common mistake that i come across is wires labelled differently on either side of a terminal block. A terminal block is nothing but a way of connecting two wires, it does not have any effect on what is occuring with that particular peice of wiring (ie Change of State), and as such its wire number should not change.
Thats my opinion anyway.

 

[MikeW]

Hi,

Same number both ends, first two digits are originating page number second two digits are incremented per wire. The wire number stays the same until it passes through a device that switches or alters the characteristics of the potential. i.e. wires passing through terminals stay the same whereas wires passing through a relay contact change. This keeps all wire numbers to four digits generally, unless the panel requires 100+ drawings in which case I increase the page number prefix to 3 digits throughout the set.

The quandary I find is what to do with the interposing signal wiring between 2 panels, any suggestions?

Cheers,

Lee

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