# OEM’s and panduit



## varmit (Apr 19, 2009)

Unfortunately, what you describe is way too common. Even worse is panel wiring with no numbering and packed so tight in the panduit that you can't even pull on the wire to trace it out. 

The worst that I have dealt with was some ancient German machine panels with unmarked solid wire packed into some of the smallest wireway (panduit) that I have ever seen. I had to reverse engineer the panel and make sketches one wire at a time. Not a quick fix.


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## dronai (Apr 11, 2011)

Yeah the Euro panels are the tightest I've seen. Different rules than a UL508 shop has to follow


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## ElectricMatt (Dec 29, 2016)

The worst part is that the cabinet is 3’x7’x 24” with a PF753 for a 300hp motor. It’s a pretty good sized vfd, but only 10% (or less) of the cabinet is used for the controls, which is an over engineered mess of relays, timers,and auxiliary contactors. 

I would be willing to bet their is over 150 wires, a dozen and a half relays, half a dozen timing relays, 12 terminal blocks, that give minimal control and feedback. 

It is a prime example of an over engineered(engineers please don’t take this as an insult) mess. I could have accomplished the same thing with only a small PLC that would accomplish the same thing with minimal wiring. 

Why in this day and age are we still doing this, and then shoving it all in the smallest panduit we can find. 


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## glen1971 (Oct 10, 2012)

I asked a project designer once why pretty much every piece of panduit on that job was undersized. He said it was calculated properly, so I showed him one of the DCS cabinets. He said we had left too much wire in there, that his design had accounted for each wire once. I said that's great, but most guys take that wire to the lowest terminal, strip every wire, then land them wherever they go on the rail, so it will have twice as many wires. Unless it was designed that all of the cables terminate in one defined section of the rail, but even then the top wire could still reach the bottom terminal. He couldn't see why we'd do it that way and let's just say he wasn't keen on changing in the future.


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## ElectricMatt (Dec 29, 2016)

glen1971 said:


> I asked a project designer once why pretty much every piece of panduit on that job was undersized. He said it was calculated properly, so I showed him one of the DCS cabinets.  He said we had left too much wire in there, that his design had accounted for each wire once. I said that's great, but most guys take that wire to the lowest terminal, strip every wire, then land them wherever they go on the rail, so it will have twice as many wires. Unless it was designed that all of the cables terminate in one defined section of the rail, but even then the top wire could still reach the bottom terminal. He couldn't see why we'd do it that way and let's just say he wasn't keen on changing in the future.




My guys and myself always leave some additional wiring(within reason) when terminating. Because as we all know regardless of where the prints at it goes, there is always a chance at startup that something was wrong; or changed without being updated on the prints. 

Again, is it really that much more expensive to upsize your panduit. When building cabinets I always move my panduit up to the next size. Also, and this is a novel idea, leave a little room to add some additional devices in the future. The most common thing I find myself adding is terminal blocks, relays, and small motor starters. So I try to design with a little room for those things in the future. 


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## splatz (May 23, 2015)

TBH I have given myself a headache with this. What's a good rule of thumb for the amount of wires you can comfortably fit in a duct? 

I have been using the conduit fill tables - so if the fill tables say to use 1.5" conduit, I use 1.5" square duct. I thought that would be plenty of space - the tables are based on 40% and 1.5" square is bigger than 1.5" round. But it doesn't really work out that way.


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## ElectricMatt (Dec 29, 2016)

splatz said:


> TBH I have given myself a headache with this. What's a good rule of thumb for the amount of wires you can comfortably fit in a duct?
> 
> I have been using the conduit fill tables - so if the fill tables say to use 1.5" conduit, I use 1.5" square duct. I thought that would be plenty of space - the tables are based on 40% and 1.5" square is bigger than 1.5" round. But it doesn't really work out that way.




If you count each wire as individual then you will find yourself with panduit too small. I use 1.5 as a multiplier for the amount of wires in duct to account for wires crossing at termination points and around corners. 


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## telsa (May 22, 2015)

It's a European cultural 'thing.'

It's a rare day when a German EE will talk to a German assembly tech. If it looked good on the CRT// paperwork -- then it's good to go -- for the EE.

Denning started a revolution manufacturing -- in Japan -- by forcing the engineers to build their own designs -- right on the factory floor. They promptly ran back upstairs and re-configured everything for ease of assembly. The Germans are two-generations behind the Japanese... and they know it.

Now BMW & Daimler-Benz are chasing after Toyota and Nissan.

What's true in automotive -- is just as true in electrical assemblies.


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## gpop (May 14, 2018)

20 years ago i looped the wire in the panduit before terminating then i realized that i wasn't doing anyone a favor. I also use to run spares until i realized there just about useless compared to a string. 

As a maintenance electrician i hate people who leave loops in panduit. If you want to be thoughtful leave a few terminal blocks as spares, That way we can either use them or pop them out to add a relay.


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## dronai (Apr 11, 2011)

gpop said:


> 20 years ago i looped the wire in the panduit before terminating then i realized that i wasn't doing anyone a favor. I also use to run spares until i realized there just about useless compared to a string.
> 
> As a maintenance electrician i hate people who leave loops in panduit. If you want to be thoughtful leave a few terminal blocks as spares, That way we can either use them or pop them out to add a relay.



Forget the loops in paduit, but I learned the hard way with the spares. We always run spare control wires


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## glen1971 (Oct 10, 2012)

gpop said:


> 20 years ago i looped the wire in the panduit before terminating then i realized that i wasn't doing anyone a favor. I also use to run spares until i realized there just about useless compared to a string.
> 
> As a maintenance electrician i hate people who leave loops in panduit. If you want to be thoughtful leave a few terminal blocks as spares, That way we can either use them or pop them out to add a relay.


I leave all of my spares outside the panduit, usually coiled up in a wireway, tophat, etc. with white tape on them as to cable/conduit number. They are long enough to reach anywhere in the panel/box.
I could leave enough spare terminals to what I thought, but what about 3 add-ons later? Then I still wouldn't have left enough. I'd like to think that the panels I've built are big enough for the job at hand, and with room for some expansion.


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## Dennis Alwon (May 9, 2009)

I get the same result as the op when I use my android.


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## macmikeman (Jan 23, 2007)

And yet auto mechanics always have to put up with auto wiring problems but the wire bundles are all zip tied and then taped over the whole length............

1st world problems........


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## oliquir (Jan 13, 2011)

I often use narrow wire duct to keep small enclosure, but if a lot of wires needs to be pass i use 3" high wire duct, it doesn't take more space but double the wiring space


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## JRaef (Mar 23, 2009)

Most people are unaware that the MAXIMUM fill of wire duct is *50%. *1.5" x 1.5" duct is rated to hold no MORE than 33 14ga MTW conductors, less if it has the thicker insulation. 



So "looping" cuts that in half by the way; it's not the number of current carrying conductors, it's strictly fill volume.


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## glen1971 (Oct 10, 2012)

JRaef said:


> Most people are unaware that the MAXIMUM fill of wire duct is *50%. *1.5" x 1.5" duct is rated to hold no MORE than 33 14ga MTW conductors, less if it has the thicker insulation.
> 
> 
> 
> So "looping" cuts that in half by the way; it's not the number of current carrying conductors, it's strictly fill volume.


But what if all of the covers disappeared sometime prior to the turn of the century? lol..


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## splatz (May 23, 2015)

JRaef said:


> Most people are unaware that the MAXIMUM fill of wire duct is *50%. *1.5" x 1.5" duct is rated to hold no MORE than 33 14ga MTW conductors, less if it has the thicker insulation.
> 
> 
> 
> So "looping" cuts that in half by the way; it's not the number of current carrying conductors, it's strictly fill volume.


That number seems reasonable, that is 33 wires seems like a reasonable max, but is it really 50% of the cross sectional area? 

NEC table C1 shows 1.5" EMT capacity of 84 THHN #14, based on 44% fill, and a round cross section is about 3/4 a square cross section.


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## oliquir (Jan 13, 2011)

i have also seen some electrician using only 12/14 ga (because thats all they had in their shop...) wiring for sensors when it could have been 18ga, that makes a big difference in the wire duct


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## splatz (May 23, 2015)

oliquir said:


> i have also seen some electrician using only 12/14 ga (because thats all they had in their shop...) wiring for sensors when it could have been 18ga, that makes a big difference in the wire duct


Again I might be guilty of this. I have been just using most or all #14 in the panel because I heard all the big boys are specifying that, and because it seems less prone to bad terminations than #18. Might be one to rething, it would make a huge difference cramming the ducts.


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## ElectricMatt (Dec 29, 2016)

oliquir said:


> i have also seen some electrician using only 12/14 ga (because thats all they had in their shop...) wiring for sensors when it could have been 18ga, that makes a big difference in the wire duct




I like to use 16-18g, but often times engineers spec out min #14 for any field devices. So I have to use 14 in those cases. Other than that’s, as long as it’s fused appropriately, I use #16 for field wiring. 


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## dronai (Apr 11, 2011)

oliquir said:


> i have also seen some electrician using only 12/14 ga (because thats all they had in their shop...) wiring for sensors when it could have been 18ga, that makes a big difference in the wire duct


ugh !!!



splatz said:


> Again I might be guilty of this. I have been just using most or all #14 in the panel because I heard all the big boys are specifying that, and because it seems less prone to bad terminations than #18. Might be one to rething, it would make a huge difference cramming the ducts.


!!!


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## JRaef (Mar 23, 2009)

When I first got into building panels using duct (as opposed to loom), nobody told me there was a fill limit. So I stuffed them to the point of having to use ty-raps to hold the covers on! I learned that lesson when a panel I built was red-tagged on arrival. It was a very expensive lesson because I had to move everything around inside to make room for larger duct and had to ship it back to my shop and out to the site again at my expense.


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## bill39 (Sep 4, 2009)

Wire duct fill tables are about as accurate as conduit fill tables. It may be legal but try doing it. Yuck!


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## cmdr_suds (Jul 29, 2016)

telsa said:


> It's a European cultural 'thing.'
> 
> It's a rare day when a German EE will talk to a German assembly tech. If it looked good on the CRT// paperwork -- then it's good to go -- for the EE.
> 
> ...


I have seen plenty of ridiculously tight Japanese panels


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## Norcal (Mar 22, 2007)

Trying to stuff 10 pounds of manure in 5 pound bag.


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## tates1882 (Sep 3, 2010)

Just FYI 40-#18’s is legal


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