Conduit Fill Calculations for Low Voltage Wires

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JFletcher said:
That BICSI page makes no sense, sorry. Someone tell me why who owns the PBX changes the circuit to a 725 install or an 800 install? Electrically, are they not identical? Also, if I run cat6 from a patch panel (or 110 block)to a keystone, there is no telling what IT guy is going to hook to the backbone cabling. Yes, chances are high it will be IT equipment but as Hal can tell you, if it's 110 to keystone, it might just be POTS. I've never had an inspector ask me the purpose of my cabling. Maybe they dont know, dont care, or it just doesnt matter. From experience, if you use the correct cable type (CM, CMR, CMP) for the app and support/firestop it correctly, that's about all you need to pass an inspection. Sad but (mostly) true.

Also, they write that POTS is 800 but a VoIP install is 725. As Hal wrote above, that's bass ackward too.
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Other than the cable fill issue, what other code rules for the installation of the cables in question change between Article 725 and 800?
 
That is the only difference but depending on the job that could mean a lot. Also that's right now. Including ethernet in 725 opens the door for future restrictions- as mentioned changes in the 2017 code relating to POE and heat buildup.

I do understand that a wiring installation could initially be installed with no POE in mind then at some point POE might be added putting the wiring (or at least those POE runs) under 725. I could see putting all ethernet wiring in 725 as POE becomes more prevalent. But that needs to be made clear.

-Hal
 
hbiss said:
That is the only difference but depending on the job that could mean a lot. Also that's right now. Including ethernet in 725 opens the door for future restrictions- as mentioned changes in the 2017 code relating to POE and heat buildup.

I do understand that a wiring installation could initially be installed with no POE in mind then at some point POE might be added putting the wiring (or at least those POE runs) under 725. I could see putting all ethernet wiring in 725 as POE becomes more prevalent. But that needs to be made clear.

-Hal
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It is my understanding that CMP 3 has always considered Ethernet as covered by Article 725. It is just code users who have considered it covered by 800.
 
Unless they had a crystal ball that wouldn't make sense back before POE. Where did the old data wiring before Ethernet such as thinnet and token ring fit in?

-Hal
 
kwired said:
Is no NEC requirement here that I am aware of. But consider length of run, type of raceway, how full you intend to fill it, number of bends, and what kind of stress you may put on the cables you are going to pull as it may effect their performance if you pull too hard. Cat 5 and 6 cables if only slightly compromised may still function but you may not get maximum data speeds the cable is capable of either.
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It is extremely rare that I find the smoking gun on this site, but I think I might have. 800.110 (A) (1) requires communications wires and cables installed in chapter 3 raceways to comply with the requirements of chapter three, hence 40% conduit fill. Someone else can quote the exact wording as I know others can copy and paste.
 
Strathead said:
It is extremely rare that I find the smoking gun on this site, but I think I might have. 800.110 (A) (1) requires communications wires and cables installed in chapter 3 raceways to comply with the requirements of chapter three, hence 40% conduit fill. Someone else can quote the exact wording as I know others can copy and paste.
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The question has been if article 800 is the correct one.
 
iwire said:
The question has been if article 800 is the correct one.
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Review posts one and two and you will see that your statement isn't correct. It evolved in to a discussion about that, but still constantly referred to a requirement in 725 to follow chapter 3 conduit fill requirements, but no corresponding requirement in chapter 8
 
Strathead said:
Review posts one and two and you will see that your statement isn't correct. It evolved in to a discussion about that, but still constantly referred to a requirement in 725 to follow chapter 3 conduit fill requirements, but no corresponding requirement in chapter 8
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Actually, I think most referred to no identical fill limit requirement in 800. Corresponding is a weaker statement and does not require the fill percentage limits to be the same. :angel:
 
Strathead said:
Review posts one and two and you will see that your statement isn't correct. It evolved in to a discussion about that, but still constantly referred to a requirement in 725 to follow chapter 3 conduit fill requirements, but no corresponding requirement in chapter 8
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I have been following the thread all along, but regardless of that doesn't 800.110(B) change your mind?

800.110(B) Raceway Fill for Communications Wires and
Cables. The raceway fill requirements of Chapters 3 and 9
shall not apply to communications wires and cables.
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iwire said:
I have been following the thread all along, but regardless of that doesn't 800.110(B) change your mind?
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Yep, mentioned first thing in post #3.

While were on chapter 7/8 installs, what is 830 for then? What exactly is a "Network Powered Broadband Communication System"? Broadband sounds like internet to me, and maybe the FCC:

http://www.theverge.com/2015/1/29/7932653/fcc-changed-definition-broadband-25mbps

The NEC does not define broadband in either article 100 or 830.
 
iwire said:
I have been following the thread all along, but regardless of that doesn't 800.110(B) change your mind?
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Yes it does, I didn't read that far. 800.110 (A)(1) and 800.110 (B) are in direct conflict with each other. Another example of a poorly written code section. B should be an exception of (A) (1) not a stand alone paragraph.
 
Strathead said:
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Yes it does, I didn't read that far. 800.110 (A)(1) and 800.110 (B) are in direct conflict with each other. Another example of a poorly written code section. B should be an exception of (A) (1) not a stand alone paragraph.
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I see no conflict there. (A)(1) only requires that the raceways be installed per the Chapter 3 rules....it says nothing about installing conductors or cables in the raceway.
 
don_resqcapt19 said:
I see no conflict there. (A)(1) only requires that the raceways be installed per the Chapter 3 rules....it says nothing about installing conductors or cables in the raceway.
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It is a sub section of 800.110 (A) which is regarding installation of wiring in any raceway. I can see your position if I twist really hard, but if (B) did not exist then I think any of you would make the argument that (A) requires the cables to comply with chapter 3 fill. There are many very easy ways to make this clearer. On top of that, it seems silly not to require the same fill requirements as most of us know that anything that exceeds the code minimum or in this case maximum fill is not worth trying to pull in most cases.
 
Strathead said:
It is a sub section of 800.110 (A) which is regarding installation of wiring in any raceway. I can see your position if I twist really hard, but if (B) did not exist then I think any of you would make the argument that (A) requires the cables to comply with chapter 3 fill. There are many very easy ways to make this clearer. On top of that, it seems silly not to require the same fill requirements as most of us know that anything that exceeds the code minimum or in this case maximum fill is not worth trying to pull in most cases.
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The NEC is a safety code...where is the safety issue if you damage these cables because you have overfilled the conduit?
 
don_resqcapt19 said:
The NEC is a safety code...where is the safety issue if you damage these cables because you have overfilled the conduit?
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Well as much as many other sections of the code. If the ringer was shorted to the conduit and a person was on a 12 foot ladder sweating in contact with the conduit and a grounded piece of metal it could make them jump and fall 12 feet, for example. Not trying to be facetious, but definitely implying the arbitrary nature of the code some times.
 
Thanks for all the great insight. I seem to have inadvertently started a debate. But at the end of the day my question is simply:

Does the NEC require conduit fill for low voltage cabling to follow Chapter 9 Table 4?

I guess the answer depends on if you follow Article 725 or 800. I can take a poll on the matter. Simple yes/no responses please.
 
minesh21 said:
Thanks for all the great insight. I seem to have inadvertently started a debate. But at the end of the day my question is simply:

Does the NEC require conduit fill for low voltage cabling to follow Chapter 9 Table 4?

I guess the answer depends on if you follow Article 725 or 800. I can take a poll on the matter. Simple yes/no responses please.
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That is the answer. 725 says you have to follow the conduit fill rules, and 800 says you are not required to do so.

Now you have to determine what article applies to the cabling that you are installing.
 
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