HEL Plc

[ctaylo360860]

First thing is first i want to Thank all of you for any and all help! This forum is very much appreciated!!! I have never done a PLC install. The company I'm working for is changing there existing system to a plc by Kahler Automation system. There is no engineering involved so i am design this my self... the existing plant is a cobbled together mess... I see in my field wiring diagram that i have around 165 16 gauge 24voltdc conductors that go from my plc to various locations on site such as hmi, remote start/pause, emergency stops, Air solenoid valves ect. as i understand these should be considered class 2 circuits. I plan on using 16 guage thhn/thwn. I was trying to figure out my pipe fill calculations for my raceways, but was not having any luck finding anything smaller than 14guage wire.... I didnt know if there was a better solution or a type of cable that i could use.... I have a Beldan 28330a which is a 16 conductor of 16guage wires i didnt know if that was more of standard or what should be used. I planned on using pvc raceways since its a corrosive environment and i only have about 36 days to get the job complete... I will try and post some pictures to represent the specific scope of work .....

 

[EC Dan]

The circuits are only Class 2 if the power supply is listed as a Class 2 power source, but it's probably a safe assumption that will be the case. In almost all applications here for 24 VDC power and signal field distribution, I use multi-conductor ITC.

 

[ctaylo360860]

This is the plans I drew up myself it’s, sorry if not make much sense but essentially all the red boxes are where my 24 conductors need to go from plc…. Anything that is in a yellow box will need to be supplied with 120volts for the transmitter and valves…

 

[ctaylo360860]

The circuits are only Class 2 if the power supply is listed as a Class 2 power source, but it's probably a safe assumption that will be the case. In almost all applications here for 24 VDC power and signal field distribution, I use multi-conductor ITC.

This is the type of beldan cable I have…. Do normally install some type of cable rack or can this be installed inside of a raceway?

 

[ctaylo360860]

Here is what the actual plant looks like

 

[petersonra]

The circuits are only Class 2 if the power supply is listed as a Class 2 power source, but it's probably a safe assumption that will be the case. In almost all applications here for 24 VDC power and signal field distribution, I use multi-conductor ITC.

I would not assume that at all. Class 2 power supplies are by definition less than 100 VA and with that many solenoids 100 VA might not be enough. The I/O circuits are probably Class 1 conductors.

 

[ctaylo360860]

First picture- the plc goes to thr right of the door on the second floor

second picture is the nice existing electrical work…

 

[ctaylo360860]

I would not assume that at all. Class 2 power supplies are by definition less than 100 VA and with that many solenoids 100 VA might not be enough. The I/O circuits are probably Class 1 conductors.

Looks like my power supplies are all 90 watts output… diagram for the solenoids say they are all class 2 unless noted

 

[petersonra]

Looks like my power supplies are all 90 watts output… diagram for the solenoids say they are all class 2 unless noted

If it says that, than they probably are, although it is a little unusual.

If they are class 2 circuits you can use any class 2 wiring method that is allowed by article 725.

 

[EC Dan]

This is the type of beldan cable I have…. Do normally install some type of cable rack or can this be installed inside of a raceway?

I would normally use TC-ER such as what you have for Class 1 or power circuits, although more often than not those type of circuits I run with individual conductors. Either type of cable can be run in cable tray or raceway. I probably wouldn't use cable tray in your application going to multiple locations outdoors.

 

[ctaylo360860]

Thanks, I'll make sure I confirm with engineering. I'll have to read over those 17 pages, not familiar with this article...

 

[ctaylo360860]

I would normally use TC-ER such as what you have for Class 1 or power circuits, although more often than not those type of circuits I run with individual conductors. Either type of cable can be run in cable tray or raceway. I probably wouldn't use cable tray in your application going to multiple locations outdoors.

Thanks for the replies! Yeah I'm leaning towards individual 16 thhn/thwn-2 conductors inside pvc raceways.. one thing im confused about is how to do pipe fill calculations because the wire size only goes down to 14 in chapter 9 table 5 .... maybe because its a class 2 circuit i don't have to do them ?

 

[petersonra]

Thanks for the replies! Yeah I'm leaning towards individual 16 thhn/thwn-2 conductors inside pvc raceways.. one thing im confused about is how to do pipe fill calculations because the wire size only goes down to 14 in chapter 9 table 5 .... maybe because its a class 2 circuit i don't have to do them ?

Article 725 is somewhat obscure about how many class 2 conductors can be jammed in a conduit. It says you don't have to abide by anything in chapter 3 unless specifically referred to, and then refers you to 300.17 for number and size of conductors in a raceway. However, 300.17 gives no specific requirements for either.

 

[don_resqcapt19]

Article 725 is somewhat obscure about how many class 2 conductors can be jammed in a conduit. It says you don't have to abide by anything in chapter 3 unless specifically referred to, and then refers you to 300.17 for number and size of conductors in a raceway. However, 300.17 gives no specific requirements for either.

Yes, the language in 300.17 could be improved. It is a performance requirement, and not a prescriptive requirement as we typically see in the NEC. The prescriptive requirements are found in the xxx.22 sections of the raceway articles as shown in the Informational Note.

 

[ctaylo360860]

Article 725 is somewhat obscure about how many class 2 conductors can be jammed in a conduit. It says you don't have to abide by anything in chapter 3 unless specifically referred to, and then refers you to 300.17 for number and size of conductors in a raceway. However, 300.17 gives no specific requirements for either.

took me forever to find 300.17 number of conductors in a raceway..... I had planned on just doing pipe fill calculation for #14 thwn-2 and seeing how many i can get away with there, but if I'm understanding correctly there is no need to use the 40% rule in chapter 9 table 1

 

[don_resqcapt19]

took me forever to find 300.17 number of conductors in a raceway..... I had planned on just doing pipe fill calculation for #14 thwn-2 and seeing how many i can get away with there, but if I'm understanding correctly there is no need to use the 40% rule in chapter 9 table 1

It is my opinion that the reference in Article 725 to 300.17 is intended to require compliance with the xxx.22 raceway article rules that reference Chapter 9, Table 1.

Typically the 16 and 18 AWG conductors are marked as fixture wires and they are included at the end of the Annex C tables for each raceway type.

 

[petersonra]

It is my opinion that the reference in Article 725 to 300.17 is intended to require compliance with the xxx.22 raceway article rules that reference Chapter 9, Table 1.

Typically the 16 and 18 AWG conductors are marked as fixture wires and they are included at the end of the Annex C tables for each raceway type.

It does not actually say that though, and article 90 says this about informational notes. It would seem very clear that informational notes do not require compliance with anything.

(C) Explanatory Material. Explanatory material, such as references
to other standards, references to related sections of this
Code, or information related to a Code rule, is included in this
Code in the form of informational notes. Such notes are informational
only and are not enforceable as requirements of this
Code.

 

[ctaylo360860]

It does not actually say that though, and article 90 says this about informational notes. It would seem very clear that informational notes do not require compliance with anything.

i just sized my raceways based off of #14 thhn/thwn-2. I'm in house master electrican, so im not going to loose anything either way it goes. Jusy want to make sure my my install is compliant..

 

[tom baker]

For the 50+ plcs I installed, for the field wiring I used 14AWG THHN, analog inputs were Belden 1032A, power limited tray cable. if you want 16 AWG, its a TFFN type but the 14 is readily available and more tolerant on installation. You could run a multiconductor PLTC to a junction box and then transition to lower pair count or 14 AWG, but this means more splices, and more wire labeling.
We had a Greenlee cable cart and would load multiple rolls of 14, put a wire number on the spool and one on the wire end and pull many at once.
Pulling went really fast, the slow part was labeling, dressing and landing each wire. I used a Brother PTE-300 industrial labeler with heat shrink labels, looked great when all done.
Mark up your drawings as you go. I used the fuse # PLC input as the wire number. FU-1 and 2-4 would be card 2, input 4. Ideally you want a different number on each wire, so if you have two wires on Fu-1, then its FU-1-1 and FU-2-2

 

[don_resqcapt19]

It does not actually say that though, and article 90 says this about informational notes. It would seem very clear that informational notes do not require compliance with anything.

There are a number of Informational Notes that refer you to other code sections. Sure the notes themselves are not enforceable but that has NOTHING to do with the enforceability of the referenced sections.