CAT 6 cable in the same conduit as THWN wiring?

Status
Not open for further replies.
I once got a tour of a fiber optic cable manufacturing plant. One of the tests this plant performed on the final spool was to run a video signal though the fiber spool and show a test pattern on a TV. They found that using a modern TV with a digital TV signal never showed marginal fiber, while an older analog TV and signal showed marginal fiber as distortion in the test pattern.
 
tthh said:
I once got a tour of a fiber optic cable manufacturing plant. One of the tests this plant performed on the final spool was to run a video signal though the fiber spool and show a test pattern on a TV. They found that using a modern TV with a digital TV signal never showed marginal fiber, while an older analog TV and signal showed marginal fiber as distortion in the test pattern.
Click to expand...
That should surprise no one. Digital signals are generally error checked while analog signals can just go all over the place.
 
petersonra said:
That should surprise no one. Digital signals are generally error checked while analog signals can just go all over the place.
Click to expand...
In the olden days when you were watching TV over the air and the signal was weak, the video would get "snowy" but you could still watch it until it got really bad, and the audio was the last thing to crap out. These days if the signal degrades you get video shredding and freezes along with "goat boy" audio. It either works perfectly or it doesn't work at all. Is that better? :D
 
ggunn said:
In the olden days when you were watching TV over the air and the signal was weak, the video would get "snowy" but you could still watch it until it got really bad, and the audio was the last thing to crap out. These days if the signal degrades you get video shredding and freezes along with "goat boy" audio. It either works perfectly or it doesn't work at all. Is that better? :D
Click to expand...
Reminds me of the days of adjusting the rabbit ear antenna on the TV "just so" to get the best signal. Sometimes, you had to not let go of it because your body contact improved the reception! 🤪
 
don_resqcapt19 said:
Your only options are in 725.136(I).
Click to expand...
Allen Bradly makes a 600 Volt rated Cat5 cable I have seen used. Its cat5 not 6
The 600V sheath is as thick as any barrier, so an AHJ might agree it meets the requirement of a barrier 725.136(B). There is no NEC definition of a barrier in that context.
www.belden.com

600V Industrial Ethernet Cable: Safety & NEC Considerations

Installing Ethernet on the factory floor is not new. What is changing is its adoption for controlling communications to power-hungry machines, often in areas...
www.belden.com www.belden.com
 
jaggedben said:
How would one know this? Are network devices (routers, switches) so marked?
Click to expand...
It really gets down to the definition of a communications circuit. The rules in 800 (805 in the 2020) for communications equipment end at the load side of the first customer owned equipment. This also puts phone wiring on the building side of a private PBX into Article 725.
"Article 725 Class 1, Class 2, and Class 3 Remote-Control, Signaling, and Power-Limited Circuits."
The ethernet circuits and phone circuits on the building side of the equipment are considered "signaling" circuits and are covered by 725.
There is no practical difference as the rules in both 725 and 805 are almost identical.

Note that there are really no specific rules for "signaling circuits" in Article 725, but the Class 2 rules are typically applied to those circuits.
 
jaggedben said:
How would one know this? Are network devices (routers, switches) so marked?
Click to expand...
Just take a peek in your network closet, look at the power supply for your network switch or router, dont accidentally unplug your office network, do you see anything that says class 2 on it?
That would be a art 725.121 (A)(2) class 2 power supply.
A communications circuit as defined by article 800, I think of like 'service conductors' they originate from a provider, enter the building then go to all the customer owned equipment such as old landline phone, fax, T1 or DSL modems, stopping when that equipment powers a new circuit off local power.
Or the coax/fiber from the street to the first modem.

Like I said they make cat 5 and even cat 6 that is crush resistant and for any AHJ I know meets the 'barrier' requirement in 725.136(B)
www.belden.com

Industrial Category 6A Cable

www.belden.com www.belden.com
 
Last edited:
Jon456 said:
Reminds me of the days of adjusting the rabbit ear antenna on the TV "just so" to get the best signal. Sometimes, you had to not let go of it because your body contact improved the reception! 🤪
Click to expand...
I still have to do that for over the air reception. The difference is in what lower quality digital signal looks like vs analog. With analog "close enough" works but not so for digital.
 
tortuga said:
Just take a peek in your network closet, look at the power supply for your network switch or router, dont accidentally unplug your office network, do you see anything that says class 2 on it?
That would be a art 725.121 (A)(2) class 2 power supply.
A communications circuit as defined by article 800, I think of like 'service conductors' they originate from a provider, enter the building then go to all the customer owned equipment such as old landline phone, fax, T1 or DSL modems, stopping when that equipment powers a new circuit off local power.
Or the coax/fiber from the street to the first modem.

Like I said they make cat 5 and even cat 6 that is crush resistant and for any AHJ I know meets the 'barrier' requirement in 725.136(B)
www.belden.com

Industrial Category 6A Cable

www.belden.com www.belden.com
Click to expand...
As far as I know there is no cable on the market that meets the requirements in 725.136(I)(1) or (2). The cable that is used inside MC for 0-10 volt dimming controls is specifically listed for that purpose.
 
don_resqcapt19 said:
As far as I know there is no cable on the market that meets the requirements in 725.136(I)(1) or (2).
Click to expand...
(2017) 725.136(I)(1)(b) includes the term "metal-sheathed" cables, which strikes me as a general term, not referring to any specific Chapter 3 wiring method, unlike the other options ("metal-clad, non-metallic sheathed, or type UF"). So how about an armored Cat5 cable inside a raceway with individual power conductors? That would seem to qualify as "metal-sheathed" to me.

E.g., to pick a random brand:


Cheers, Wayne
 
wwhitney said:
(2017) 725.136(I)(1)(b) includes the term "metal-sheathed" cables, which strikes me as a general term, not referring to any specific Chapter 3 wiring method, unlike the other options ("metal-clad, non-metallic sheathed, or type UF"). So how about an armored Cat5 cable inside a raceway with individual power conductors? That would seem to qualify as "metal-sheathed" to me.

E.g., to pick a random brand:


Cheers, Wayne
Click to expand...
I believe it was written that way to permit both MC and AC cables, but I see no reason why armored CAT5 would not be acceptable.
I kind of see the same issue where they use the term non-metallic sheathed, without actually specifying Type NM cable.
 
Status
Not open for further replies.
Top