# Wiring in PLC control panels



## LuckyLuke (Jun 1, 2015)

We never loop around like that, at most we leave a couple inches maximum so you can move over a few terminals left or right if additions are made. Tyraps in duct is a ridiculous practice, only time I allow that is when there is several conductors being run and we put in the occasional one that is loose so we can run the conductors without them falling out. Once complete we remove those tyraps.


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## dawgs (Dec 1, 2007)

Not sure why the would leave all the slack unless they were unsure of something. As far as jumping strait into the panduit, well why would you not? That's how I've done it for 25 years. That's what it's there for.


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## MechanicalDVR (Dec 29, 2007)

Sounds like the guy went overboard on leaving a little extra wire in the duct. There are times I've marked out pairs to specific sensors or devices with small coloured ties for easy id afterwards.


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## splatz (May 23, 2015)

I sometimes go a little heavy on the slack. Sometimes I'll cut everything the same length, so every wire is long enough to reach every terminal. But unless it's super crowded in there, there are better ways to organize the slack than stuffing it all in the duct. I am not a fan of tie wraps inside the duct, no point in nailing it down inside the duct.


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## psgama (Oct 26, 2015)

If there is not an auxiliary gutter, all spares are to be left in the panduit with enough length to go anywhere in the panel. Anything terminated should have enough length to be moved 6 terminals up or 6 terminals down. 

That's how we've done our installs for years, keeping them nice and neat.


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## blueheels2 (Apr 22, 2009)

Auxillary gutter is the way to go. Leave all the slack you want down there and the cabinet is a breeze to work in.


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## Cow (Jan 16, 2008)

Maybe the electrician has worked with other panel builders in the past who liked to move things around on them and he's just trying to make sure there is some slack.

The simple answer to your question is, ask the electrician why he's leaving so much slack.

I've done wiring in quite a few panels, we just make sure to swoop into the terminals with as much slack as possible, then you know you could move a wire a couple inches either way in the future. Any slack beyond that gets messy quick.


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## bill39 (Sep 4, 2009)

Cow said:


> Maybe the electrician has worked with other panel builders in the past who liked to move things around on them and he's just trying to make sure there is some slack.
> 
> The simple answer to your question is, ask the electrician why he's leaving so much slack.
> 
> I've done wiring in quite a few panels, we just make sure to swoop into the terminals with as much slack as possible, then you know you could move a wire a couple inches either way in the future. Any slack beyond that gets messy quick.


I probably will ask the next time I'm onsite. I just wanted to run it by here first to get some other opinions.

I completely understand the reason for leaving the wires long in case something needs to be changed, it's just putting all of the extra into the wire duct that doesn't make sense.


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## bill39 (Sep 4, 2009)

blueheels2 said:


> Auxillary gutter is the way to go. Leave all the slack you want down there and the cabinet is a breeze to work in.


I agree with you if there is enough room above or below the panel for the gutter. Also, unless it's specified there is the matter of who pays for the gutter.

Years ago, the local Ford plant required 6 ft of extra wire be left in the bottom of the panel.


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## MechanicalDVR (Dec 29, 2007)

bill39 said:


> I probably will ask the next time I'm onsite. I just wanted to run it by here first to get some other opinions.
> 
> I completely understand the reason for leaving the wires long in case something needs to be changed, it's just putting all of the extra into the wire duct that doesn't make sense.


It looks neater when the cover is on than having loops hanging out in space. The guy doing it thinks it looks more professional. Neatness counts.


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## glen1971 (Oct 10, 2012)

Unless specs supersede I route them into the panduit they terminate in and cut them all the same length - long enough to reach the bottom of the strip. I don't leave spare wires from conduits or cables in the panduit.. That makes them tougher to find later on... Tyrap them neatly outside of the panduit in the bottom of the panel and make sure they are labelled with white tape with cable number, cores, etc... Sometimes I'll tyrap in the panduit, but rarely tight..


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## Flyingsod (Jul 11, 2013)

I have in the past left too much slack wire running back and forth in the Panduit. It's not a favored practice for me but sometimes I labeled the wires before I pulled them in and don't want to cut and re-label them. Maybe time is short, or im out of labels, or I just want to get the hell out of there.


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## KennyW (Aug 31, 2013)

Good comments. For me: 

- Just a couple inches of loop, long loops in the panduit suck. 

- Spare cores coiled up, left in the bottom of the panel, labelled what cable they belong to. Do not put the spare cores in the panduit where they will never be found/identified. 

- Cable ties sparingly, and not pulled tight, just enough to keep everything from flopping out of the duct when the cover is removed.


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## dawgs (Dec 1, 2007)

KennyW said:


> Good comments. For me: - Just a couple inches of loop, long loops in the panduit suck. - Spare cores coiled up, left in the bottom of the panel, labelled what cable they belong to. Do not put the spare cores in the panduit where they will never be found/identified. - Cable ties sparingly, and not pulled tight, just enough to keep everything from flopping out of the duct when the cover is removed.


I use rubber bands on the panduit to hold the wires in place while working in the panel. Sometimes I leave them in there so the wires don't spill out when taking the covers back off.


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## John Valdes (May 17, 2007)

When I built control panels, I always put only the interior (panel) wires in the channel.
Anything that left the panel to go remote would never get mixed up with the interior control cabinet wiring.
The terminal strip is where panel wires ended and remote wires started.

Leaving extra wire is just a personal taste thing and unless it hampers the installation, I would have no problem with it.


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## bill39 (Sep 4, 2009)

John Valdes said:


> When I built control panels, I always put only the interior (panel) wires in the channel.
> Anything that left the panel to go remote would never get mixed up with the interior control cabinet wiring.
> The terminal strip is where panel wires ended and remote wires started.
> 
> Leaving extra wire is just a personal taste thing and unless it hampers the installation, I would have no problem with it.


Guys, thanks for all of the input.
I understand and agree that neatness counts and that is why some of you said to put all of the wire in the duct. My point is that the way these guys did it will make it impossible to try and troubleshoot things later. You won't be able to tug on a wire to see where it goes.


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## JRaef (Mar 23, 2009)

So how full is the duct? Most people think that you can just fill it until you can't snap the cover on. That's incorrect. There are formulas involved, but generally it maxes out at 50%, in which case tugging a wire to trace it isn't going to be a problem. Since you indicate that's already a problem, I'm willing to bet that the person doing this extra wiring didn't know that.

Now I know the 5h!7 storm is about to flow in from guys who have been stuffing Panduit to the bursting point for years and never heard of this, but believe me, it's true. RTFM...


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## dawgs (Dec 1, 2007)

JRaef said:


> So how full is the duct? Most people think that you can just fill it until you can't snap the cover on. That's incorrect. There are formulas involved, but generally it maxes out at 50%, in which case tugging a wire to trace it isn't going to be a problem. Since you indicate that's already a problem, I'm willing to bet that the person doing this extra wiring didn't know that. Now I know the 5h!7 storm is about to flow in from guys who have been stuffing Panduit to the bursting point for years and never heard of this, but believe me, it's true. RTFM...


Those problems arise when the panel designer fails to make the enclosure large enough to accommodate the correct size panduit needed to keep this from being a problem.


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## JRaef (Mar 23, 2009)

dawgs said:


> Those problems arise when the panel designer fails to make the enclosure large enough to accommodate the correct size panduit needed to keep this from being a problem.


It certainly starts there, but a lot of panels are built and designed on the fly, or competitive pressures from someone like that forces the issue. When I built panels, I was often bigger than my competitors and lost the projects. Then later if I saw them installed, that's one thing I found a lot.


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## John Valdes (May 17, 2007)

bill39 said:


> Guys, thanks for all of the input.
> I understand and agree that neatness counts and that is why some of you said to put all of the wire in the duct. My point is that the way these guys did it will make it impossible to try and troubleshoot things later. You won't be able to tug on a wire to see where it goes.


We should not have to tug on wires to see where they go. But unfortunately we have to sometimes. Many times.
The key is numbering and numbering so the numbers stay put.
Back in the day we had no numbering machines, just peel off numbers. They were notorious for falling off and leaving a sticky gluey mess.
I always put clear shrink wrap on those type, peel off numbers. Basically encasing the number in clear plastic.
I know I say this all the time, but I'm going to say it again.

Put a number on each end of every wire you install in a panel. Put a number on each end of every single wire you use or you find without a number.
Use a numbering system that keeps the numbers attached to the wire in extreme heat or cold.
Draw the print or follow a print where the numbers actually represent the numbers on each wire.
ALWAYS note any wiring changes on the prints. ALWAYS!
I do understand many of you guys work in different places with different customers and cannot do this. These points are for the panel builder and the installation people.
We cannot control what others do once we are gone. We can educate, but once we leave, they will do as they please no matter how stupid it is.


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## KennyW (Aug 31, 2013)

JRaef said:


> So how full is the duct? Most people think that you can just fill it until you can't snap the cover on. That's incorrect. There are formulas involved, but generally it maxes out at 50%, in which case tugging a wire to trace it isn't going to be a problem. Since you indicate that's already a problem, I'm willing to bet that the person doing this extra wiring didn't know that.
> 
> Now I know the 5h!7 storm is about to flow in from guys who have been stuffing Panduit to the bursting point for years and never heard of this, but believe me, it's true. RTFM...


The trouble is that the "manual" is a bit misleading - try putting the number of conductors that constitutes "50% fill" into a panduit. 50% fill electrically is closer to 100% fill physically. 

Best example is #14 thhn since 100 of them uses up 1 square inch. So a 2x2 panduit is "50% full" with 2 square inches of conductors in it, or 200 x #14s. 

200 #14s in a 2x2 complies with the rule but that would certainly not be easy to work with. 

I think the problem is engineers who have never worked on a panel actually do read the manual and take it too literally and expect that designing it to 50% fill means the panduit will only look 50% full physically when built.
If you want the panduit to actual only be 50% full you need to use more like 30% when using the tables.


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