Best Practices for Old Wiring in Electrical Cabinet s

Thread Starter

beaug45

Joined Aug 24, 2017
3
We are re-purposing an old process plant for a new process and as part of that we are installing new hardware and wiring. In the electrical cabinet, much of the old wiring is redundant and has been disconnected. I do not want to remove this wiring as it has already been run from the cabinet to the plant equipment and may be useful as we work out the kinks of the new process and install new equipment in place of the old. Currently, we cap and tape the ends and bundle them with zip ties into logical groups, but the cabinet still looks very cluttered. Anybody know of any best practices or life hack that would help mitigate the mess?
 

MrChips

Joined Oct 2, 2009
24,621
I'm no expert here but I would rip out the old wiring assuming that it is out of date.
If you need to install new wiring later you would want to install armored cable or rigid conduit. Check the building and electrical code in your jurisdiction.
 

MaxHeadRoom

Joined Jul 18, 2013
23,924
We are re-purposing an old process plant for a new process and as part of that we are installing new hardware and wiring. In the electrical cabinet, much of the old wiring is redundant and has been disconnected. I do not want to remove this wiring as it has already been run from the cabinet to the plant equipment and may be useful as we work out the kinks of the new process and install new equipment in place of the old. Currently, we cap and tape the ends and bundle them with zip ties into logical groups, but the cabinet still looks very cluttered. Anybody know of any best practices or life hack that would help mitigate the mess?
The current method for a few decades now is to convert control cabinetry to PLC.
You end up with a cabinet 1/5 to 1/10 the size!
Makes trouble shooting a zip.
The problem I have found with these type of older systems is that mods have been made over the years and not been documented, making it a nightmare to trouble shoot.
At the very least I would suggest you document every change done and ensure that the current system has up to date documentation.
Obtain a copy of NFPA79.
Max.
 

GopherT

Joined Nov 23, 2012
8,012
We are re-purposing an old process plant for a new process and as part of that we are installing new hardware and wiring. In the electrical cabinet, much of the old wiring is redundant and has been disconnected. I do not want to remove this wiring as it has already been run from the cabinet to the plant equipment and may be useful as we work out the kinks of the new process and install new equipment in place of the old. Currently, we cap and tape the ends and bundle them with zip ties into logical groups, but the cabinet still looks very cluttered. Anybody know of any best practices or life hack that would help mitigate the mess?
You will spend 10x the time (labor dollars) to sort through what is there and trying to imagine/decide what it might be used than if you would rip it out and start over with what you want and need.

Also, if you do try to salvage it, chances are, you will still be running many new wires because there is never a perfect set of wires in place. Once you start doing that, you have a mess of new and old - it is eventually like someone working on a dirty desk - only the desk's owner knows what is going on and new employees will never be able to figure out what is going on.

Copper wire is cheap, a nice clean work space is invaluable.

Start over!
 
You failed to mention if it's process wiring or something else.

Anyway, best practices in my opinion is to bring stuff to a terminal block near the point of entry to the cabinet and then put to DIN terminals. I generally use 2 tier although 3 tier are available. Anything in the cabinet gets cross-connected from there. This is similar how telco is wired in a building prior to VoIP. All future upgrades are taken care of unless the wiring fundamental changes as it might with Ethernet or Fieldbus standards. Remember to shield at one end only.
 

MaxHeadRoom

Joined Jul 18, 2013
23,924
Over time I have converted quite a few assembly line processes that were controlled by relay logic in large cabinets, the efficiency and ease of trouble shooting went way up after converting to PLC's.
One thing to note as to wire colours is that the conductor colour for any conductor powered from a remote panel and may be live is now Orange rather than Yellow as it used to be, now conforms to the EU standard.
This is where the NFPA79 comes in handy.
Max.
 

Thread Starter

beaug45

Joined Aug 24, 2017
3
Thank you for the replies.

@KeepItSimpleStupid Yes, this is process wiring that was wired to flow valves, indicators, etc. The PLC is connected to a 2-tier terminal block and the process wiring runs out and returns at the block. we have been able to reuse a lot of the wiring but because the new process is much simpler than the old there were a lot of unused wires just sitting at the bottom of the cabinet. I wanted to clear them out but the veterans want to leave them in case they could be useful. I was hoping to figure out a way to keep them and not have the cabinet be so cluttered.

@MaxHeadRoom The old system that we are replacing is a PLC-5 system. It was installed in 2015 by an employee that is no longer here (because that is what he was familiar with). We are replacing the PLC-5 hardware with ControlLogix processor and Flex I/O hardware.
 

strantor

Joined Oct 3, 2010
5,695
Thank you for the replies.

@KeepItSimpleStupid Yes, this is process wiring that was wired to flow valves, indicators, etc. The PLC is connected to a 2-tier terminal block and the process wiring runs out and returns at the block. we have been able to reuse a lot of the wiring but because the new process is much simpler than the old there were a lot of unused wires just sitting at the bottom of the cabinet. I wanted to clear them out but the veterans want to leave them in case they could be useful. I was hoping to figure out a way to keep them and not have the cabinet be so cluttered.
If you're not at liberty to rip out the wiring then install a new terminal strip and terminate all the wires to it.

@MaxHeadRoom The old system that we are replacing is a PLC-5 system. It was installed in 2015 by an employee that is no longer here (because that is what he was familiar with). We are replacing the PLC-5 hardware with ControlLogix processor and Flex I/O hardware.
WHAT?

This technology has been obsolete for over a decade.

Rockwell released an official obsoletion notice in 2012, 3 years before your guy installed that.

This guy, ... this makes me angry. You should not have to retrofit a system that's only 5 years old. I bet those PLC-5's cost a fortune (assuming ordered new).
 

MaxHeadRoom

Joined Jul 18, 2013
23,924
I wanted to clear them out but the veterans want to leave them in case they could be useful. I was hoping to figure out a way to keep them and not have the cabinet be so cluttered.
.
I would retain a small number and remove the rest.
Terminate neatly and mark them at each termination point.
Document.
Max.
 

MisterBill2

Joined Jan 23, 2018
9,825
The current method for a few decades now is to convert control cabinetry to PLC.
You end up with a cabinet 1/5 to 1/10 the size!
Makes trouble shooting a zip.
The problem I have found with these type of older systems is that mods have been made over the years and not been documented, making it a nightmare to trouble shoot.
At the very least I would suggest you document every change done and ensure that the current system has up to date documentation.
Obtain a copy of NFPA79.
Max.
The post did not mention what the controls system was, so it may have been a PLC, since they have been around a long time. And just because wires are old is no valid reason to scrap them if they are not damaged. Between copper wire cost and pulling new wire labor costs it makes the most sense to keep them in place if they are easily usable. As far as the cluttered appearance, that is why there ARE bottom areas in cabinets. That is where the spare wires are kept. Not all tie-wrapped, but folded back neatly and then bundled neatly. Few things are more nasty than needing to quickly add something to a system and discovering that somebody has removed all of the spare wires because they did not look pretty. That cost one organization that I did some work for three days of production while the spares were replaced so that a needed modification could be made. So put a cover over those unused wires with a label that says "SPARES" . All of the USA auto companies tend to demand at least 10% spares in their electrical control cabinets.
 

strantor

Joined Oct 3, 2010
5,695
just because wires are old is no valid reason to scrap them if they are not damaged. Between copper wire cost and pulling new wire labor costs it makes the most sense to keep them in place if they are easily usable. ... Few things are more nasty than needing to quickly add something to a system and discovering that somebody has removed all of the spare wires because they did not look pretty.
Yes I can agree with this. I have ran spares myself, for "future proofing"

As far as the cluttered appearance, that is why there ARE bottom areas in cabinets. That is where the spare wires are kept. Not all tie-wrapped, but folded back neatly and then bundled neatly.
I can't bring myself to agree with this one. you should be able to sweep out the bottom of a cabinet IMO.

So put a cover over those unused wires with a label that says "SPARES"
Per the quoted section below, I'm not sure if they're more appropriately labeled "spares" or "unknowns" :D

In the electrical cabinet, much of the old wiring is redundant and has been disconnected.... Currently, we cap and tape the ends
A terminal strip would get rid of all the excess wire coiled/bundled in the bottom of the cabinet, and eliminate the risk of one of those "spares" being the unused NC contact of a 120V limit switch somewhere that decides to go hot while you've got your hand in there, or arc against the panel bottom. And it would look like it's supposed to be there.
 

MaxHeadRoom

Joined Jul 18, 2013
23,924
Well I guess if they were held for spares, he probably made good use of them.:rolleyes:
Typical of A.B. products, they were worth a lot in their day.
Max.
 
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