# Control wiring number schemes



## mburtis (Sep 1, 2018)

This ought to make for an interesting disscusion. What's everybodys favorite scheme for numbering control wiring. One of our plants has most things labeled with the loop number from the p&id loop drawings, ie FIT 352.A, ....B, etc. These work OK, but requires you to study the drawings pretty intently to know what anything is, and requires the drawing to exist and be up to date. Some of our stuff has no labels, or have labels but they don't mean anything because I haven't found the drawings yet. 

Other ideas I've heard is labeling with the plc address, such as 03:04 (slot 3 channel 4). I've seen some just random numbers.

Reminds me of back in my mechanical design days and developing part numbers. Sorta two schools of thought, one camp adds a bunch of prefixes and abbreviations to try to make the part number itself provide information. While the other just picks a random combination of letters and numbers that don't mean anything. I'm usually in the random number camp.


----------



## LARMGUY (Aug 22, 2010)

Tell me the logic of the random number camp. I'm in the prefix abbreviations camp. At least you have half the battle won when the label provides the information.


----------



## Jlarson (Jun 28, 2009)

I want my labels to match my points in the program as much as possible so no random numbers, same with on the more plain jane relay/starter/pushbutton side of the panel, labels should convey the item controlled, purpose (hand, auto, open, close) 

When we're doing labeling schedules we try and make it so with a little bit of looking at the panel you should be able to hit the ground running even without the drawings.


----------



## paulengr (Oct 8, 2017)

Use GE style!!

Each wire refers to page/line/column on the print, as the destination. So each end gets a different number. This will drive you bat blank crazy troubleshooting it.


----------



## Peewee0413 (Oct 18, 2012)

paulengr said:


> Use GE style!!
> 
> Each wire refers to page/line/column on the print, as the destination. So each end gets a different number. This will drive you bat blank crazy troubleshooting it.


I don't mind it for relay logic. 

Sent from my SM-G998U using Tapatalk


----------



## mburtis (Sep 1, 2018)

LARMGUY said:


> Tell me the logic of the random number camp. I'm in the prefix abbreviations camp. At least you have half the battle won when the label provides the information.


Again this comes from more of a mechanical assembly part number background rather than electrical, but same basic concept. The problem I ran into with "smart part numbers" is that unless your dealing with very simple stuff, in order to provide enough information in the number itself you end up with numbers that are a very complex and very long. Smart numbering systems also take more management and training in order to keep any sort of consistency and therefore usefulness. 

Seems some companies have taken this to the extreme with wire numbers that include far end location, far end terminal number, loop number, close end location, close end terminal number, etc,etc. I couldn't imagine typing all this into a labeler let alone trying to read a wire number that's 3 inches long inside a cramped panel. 

One thought I had was a very simple system structured like x-xxxx where the number in front of the dash was a panel/equipment identifier so when wires left the panel you would have 1-xxxx or 5-xxxx etc. and then have a directory identifying what the panel numbers mean.


----------



## SteveBayshore (Apr 7, 2013)

Here are the first 2 pages out of 8 pages of a ladder diagram that we designed & built for an air stripper in '99. Ladder rungs are sequentially numbered using 3 digits. All conductors have 4 digit numbers with the first three digits being the rung numbers where they originate and the last digit being the number of the conductor originating on that line. All components have 3 digit designations that correspond to the line numbers. Motor-105, Control Relay-105 or Timer-105. Easy to locate wires or components when troubleshooting. Under the unit description on the right- hand rail are the rung numbers where the relay contacts can be located. Over-lined numbers designate normally closed contacts. Before anyone asks, I haven't run into any design/build yet that actually needed more than 9 conductors originating on one line or more than 900 rungs of hard wiring. Also allows for adding wiring in the middle of a completed diagram or project and the added conductor numbers will still make sense. There are notes in red on page 2 where we started to decommission the plant and run it without the blowers running in 2013. OK, I'm ready to get blasted. Be gentle. 
I'll post a page over the weekend from an Irish built (EU) control panel that we just installed last year.


----------



## micromind (Aug 11, 2007)

My favorite is to have the instrument number and where it lands.

For example, if the instrument is pressure transducer 13 and the wire is to the left of the terminal and it's analog in #6, my tags will be PT13/AI6+ and AI6-. If the wire is to the right of the terminal, it'll be AI6+/PT13 and AI6-/PT13.

If there's a jbox with terminal blocks, I'll label both sides of the block AI6+/PT13, same for -.

Out at the instrument, I'll use AI6+ and AI6-.

I do digital a bit differently, since a digital PLC block usually has a light indicating whether the in/out is on or off, I include the address in the label.

For example, pressure switch low 22 and rack 2 slot 4 channel 8, at the PLC I use PSL22/8.

If there's a jbox with terminal blocks, I'll label both sides of the block PSL22/R2SL4CH8.

At the instrument, I'll label R2SL4CH8.

This makes it easy to troubleshoot, you don't need drawings.

If the pressure is known to be low and I don't know the PLC address and I don't have drawings, I'll open the switch and look at the label. Then I'll look at the PLC, if the light is on, the trouble is from the PLC toward the operators screen. If the light is off, I'll jumper the terminals at the PLC and if it's good then I'll check voltage starting at the PLC and work toward the pressure switch.


----------



## mburtis (Sep 1, 2018)

paulengr said:


> Use GE style!!
> 
> Each wire refers to page/line/column on the print, as the destination. So each end gets a different number. This will drive you bat blank crazy troubleshooting it.


This seems terrible and defeats the entire purpose of a wire number to me. In my mind a wire number is to give a unique identifier to the wire itself.


----------



## gpop (May 14, 2018)

mburtis said:


> This seems terrible and defeats the entire purpose of a wire number to me. In my mind a wire number is to give a unique identifier to the wire itself.


Worst is a place designed to always have the prints available and a engineering department who decided to keep the prints as they are the engineers. Then you just need to buy a dam good tracer.


----------



## mburtis (Sep 1, 2018)

I had to ask I dont know how many times for new prints when they upgraded our plcs a couple years ago.


----------



## wiz1997 (Mar 30, 2021)

gpop said:


> Worst is a place designed to always have the prints available and a engineering department who decided to keep the prints as they are the engineers. Then you just need to buy a dam good tracer.


My problem is when I add to or change wiring in a panel I red line the prints that are in the panel and a copy I keep in the shop.
The engineer figured this out and takes both prints to "update" them and never does.
I've had to break into his office when I'm on night shift to get the drawings back.
He has no clue as to how to wire anything, but is kin to someone.
Luckily they let him go a few months ago and realized they don't need him.

Most of our equipment comes from Europe and their wire numbering takes a bit getting use to.


----------



## SteveBayshore (Apr 7, 2013)

Here is page 7 of 12 for a European (Irish) machine we installed about a year ago. I added the notes in yellow so it would be easier for me to understand in the field. Like wiz1997 said, its hard to get used to. I added the pink notes. I noticed problems in the field while installing the unit. I sent these marked up plans back to the OEM. Their start-up tech was on the site for 3 days trying to get the thing to run. I requested a set of diagrams with my corrections and wiring changes that their field tech made during start up. Nothing. 😶 😶 I just sent My marked up copy to their engineering department last week again with the same request??? Their red numbers are the sheet and grid number for the location of the connection or component.


----------



## bill39 (Sep 4, 2009)

I have been an electrician & electrical controls design engineer for over 45 years. There are different fields of work: industrial controls (mainly ladder diagrams), water & waste water (mainly instrumentation & loop drawings), power utility, and commercial work. The wire numbering scheme & drawing format is usually determined by which field it is.

Drawing device numbering for valves, switches, & flow transmitters, etc. are also determined by the field of work.

Then throw in international or IEC drawing formats and that adds to the mix.

We need to be careful before saying that one style is right or wrong. A wise man once said “That’s the beauty of standards; there’s so many to choose from.


----------



## MotoGP1199 (Aug 11, 2014)

I try to keep it simple so anyone can read it. I Just start from one end of my drawing on the left and move to the right starting with my first number. You then find the number you want on the drawing and multiply that number by pi(3.14) and then divide by the square root of three (1.732) and round down to the nearest 2nd decimal place. Like GE I then label each connection point instead of wire. That way if you see the number you know EXACTLY where you are on the diagram. Easy, simple clean. I used to do in in roman numerals but apparently that was confusing since they don't teach that in school anymore.


----------



## paulengr (Oct 8, 2017)

Peewee0413 said:


> I don't mind it for relay logic.
> 
> Sent from my SM-G998U using Tapatalk


Try replacing a part with GE numbering style. None of the wire numbers on the part correspond to it. At best you can use the number to track down the other end to find what the end you are working on is. Same problem with looking it up on the drawings.

The only thing opposite end wiring does is make wire tracing easier. Everything else is painful.


----------



## micromind (Aug 11, 2007)

paulengr said:


> Try replacing a part with GE numbering style. None of the wire numbers on the part correspond to it. At best you can use the number to track down the other end to find what the end you are working on is. Same problem with looking it up on the drawings.
> 
> The only thing opposite end wiring does is make wire tracing easier. Everything else is painful.


Even worse if there are no drawings.........as is usually the case.........


----------



## paulengr (Oct 8, 2017)

micromind said:


> Even worse if there are no drawings.........as is usually the case.........


Or nobody renumbered the old wiring or alterations were made and nobody redlined anything. So even if they exist they are basically illustrations, not drawings,


----------



## joe-nwt (Mar 28, 2019)

micromind said:


> My favorite is to have the instrument number and where it lands.
> 
> For example, if the instrument is pressure transducer 13 and the wire is to the left of the terminal and it's analog in #6, my tags will be PT13/AI6+ and AI6-. If the wire is to the right of the terminal, it'll be AI6+/PT13 and AI6-/PT13.
> 
> ...


I've worked with this most of my career and really like this type of addressing as well. And you are right, once you're on it, you don't need drawings, although I can see it being awkward if you are not used to it.



mburtis said:


> Seems some companies have taken this to the extreme with wire numbers that include far end location, far end terminal number, loop number, *close end location, close end terminal number*, etc,etc.


My experience with this is it stems from idiot engineers taking off a bunch of wires during end-to-end commissioning (never been a fan) and then not remembering where the wires go. Kinda like the color coding for NM jackets for idiot inspectors.....


----------



## JRaef (Mar 23, 2009)

mburtis said:


> ...but requires you to study the drawings pretty intently to know what anything is...


Uh... I tend to do that anyway when troubleshooting. But I know what you mean. At a place like that however, once you've had your head in panels at a workplace for a while you learn the numbering scheme to where you know where the other end of that wire should be without always having to look for it on a drawing.


----------



## mburtis (Sep 1, 2018)

JRaef said:


> Uh... I tend to do that anyway when troubleshooting. But I know what you mean. At a place like that however, once you've had your head in panels at a workplace for a while you learn the numbering scheme to where you know where the other end of that wire should be without always having to look for it on a drawing.


A lot of our numbers are like AIT352.A or FIT355.C. It's not terrible once you work with it a little but the way my brain works I never remember which loop is what instrument so I still have to drag out the loop drawings to find the other end.


----------



## MotoGP1199 (Aug 11, 2014)

Interesting note. From my understanding UL 508A has deleted wire numbering from there standard and it is no longer enforced.


----------



## just the cowboy (Sep 4, 2013)

Number 1 rule: Standardize your prints!!!!!!
Number 2 rule: Rule number 1 will get broken by OEM's


----------



## GladMech (Sep 18, 2020)

In principle, I really like Loop oriented wire numbers. In practice, I have only used them a few times. It requires a good naming imagination and is highly unlikely to be consistently applied by different engineers. In my experience, most EEs don't seem to value obsessive consistency like MEs.

I like straight consecutive numbers (1,2,3,4,5,6...) but only for relay logic in very small panels.

The termination point (different at each end) is insane.

I don't like the process plant style with origin/destination. The sheer length of the numbers is impossible to hold in your mind and type in.

So, similar overall standards in numerous large equipment companies over 4-1/2 decades: Sheet & Line based wire numbers for all NON-PLC wiring (707, 1313), I/O numbers for all PLC I/O (I:04/02, O:05/03), a few exceptions for main power (L1, L1A...) & motors (M103T1, T2, T3).


----------

