Communication Cable in Conduit

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Artemis

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When pulling communication cables in conduit does the 40% rule still apply? My specific application is providing conduit from a cable tray to pieces equipment for control purposes. Typically one 90 degree bend. Are there seperate charts or recommended conduit fill for these conductors?
 
The only real concern is getting the cables within the conduit without damaging them. You are permitted exceed the 40% rule for conductor raceway fill since that won't apply to Article 800 cables.
 
Artemis said:
My specific application is providing conduit from a cable tray to pieces equipment for control purposes.
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Just be sure of the cabling / circuits types you will install. If communication, then type CM or similar, no fill requirements, 90.3 > 800.113.

If ITC, then fill requirements apply, 727.3.

If control as Class 2 or 3, then CM, CL2, CL3 or PLTC.
If subject to Article 725, then 90.3 > 725.3 (Does not exempt specific Articles / Sections beyond Art. 300 and others listed) > 344.22. IMO, fill requirements would apply.
 
Heating of conductors in conduit, wireways and cables is addressed by 310.15(B)(2)(a), 310.15(B)(2)(c) etc.

76nemo said:
What exactly do you think it pertains to then?
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IMO all the conduit and raceway fill limitations have to do with protecting the conductors from damage during the installation process.
 
iwire said:
Heating of conductors in conduit, wireways and cables is addressed by 310.15(B)(2)(a), 310.15(B)(2)(c) etc.




IMO all the conduit and raceway fill limitations have to do with protecting the conductors from damage during the installation process.
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Well, you have alot more brains than me in the field, but I never looked at it that way. I have always considered fill to be based on load generated dispensation, and I still need to be persuaded otherwise.

Like I said, that's just my take, and I am wrong almost frequently:wink:
 
iwire said:
I maintain my view, conduit fill limits are not in the NEC to protect the conductors from heat damage.
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I agree, Bob has already outlined the proper Article for heat issues. The FPN's after Table 1 in Chapter 9 seem to support Bob's contention:

Table 1 Percent of Cross Section of Conduit and Tubing for Conductors
FPN No. 1: Table 1 is based on common conditions of proper cabling and alignment of conductors where the length of the pull and the number of bends are within reasonable limits. It should be recognized that, for certain conditions, a larger size conduit or a lesser conduit fill should be considered.
FPN No. 2: When pulling three conductors or cables into a raceway, if the ratio of the raceway (inside diameter) to the conductor or cable (outside diameter) is between 2.8 and 3.2, jamming can occur. While jamming can occur when pulling four or more conductors or cables into a raceway, the probability is very low.
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76nemo said:
Well, you have alot more brains than me in the field, but I never looked at it that way. I have always considered fill to be based on load generated dispensation, and I still need to be persuaded otherwise.

Like I said, that's just my take, and I am wrong almost frequently:wink:
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How about considering that you are allowed a higher % of fill (40%) with more than 2 conductors than you are allowed with 2 conductors (31%).
 
Regardless of what NEC code states, I still say it pertains to heat dispensation. I can point out several misconceptions in the NEC, but this one seems simple. On a civil note, let's argue because you have your beliefs and I have mine. Let's roll:wink:
 
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