If using chapter 8 for telephone and tv cable installation and you decide to install pullboxes for these conduits that contain these cables, are the pullboxes required to sized the same way that chapter 3 does or no? Do these conduits for low voltage cables (tv and telephone) follow the pullbox requirements for not exceeding 360 degrees of bends if you decide to use pullboxes?
Pullbox questions
- Thread starter cppoly
- Start date
- Status
mwm1752
Senior Member
- Location
- Aspen, Colo
90.3 Code Arrangement
Chapter 8 covers communications systems and is not subject to the requirements of Chapters 1 through 7 except where the requirements are specifically referenced in Chapter 8.
800.110 Raceways and Cable Routing Assemblies for Communications Wires and Cables
(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.
Chapter 8 covers communications systems and is not subject to the requirements of Chapters 1 through 7 except where the requirements are specifically referenced in Chapter 8.
800.110 Raceways and Cable Routing Assemblies for Communications Wires and Cables
(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.
Thanks, I noticed that the raceway fill does not apply to communication cables. But 800.110(A)(1) says that raceways are permitted to be used with communication cables and that they are to follow chapter 3. Now if you go to chapter 3 and look at pullbox sizing section 314.28(A), it says the minimum size for raceways containing 4 AWG or larger are required to follow the pullbox sizing rules. I?m not sure how this applies if communication cables are in raceways since they aren?t sized by AWG rating. Thoughts?
- Location
- Massachusetts
In my experience the requirements of the people having us install these types of raceways far exceed any NEC requirements.
Large raceways, limited bends, large pull boxes etc.
qcroanoke
Sometimes I don't know if I'm the boxer or the bag
- Location
- Roanoke, VA.
- Occupation
- Sorta retired........
I agree.
mwm1752
Senior Member
- Location
- Aspen, Colo
Installation of raceways-- mounting, support n -- 800.110(B) seems to be specific to fill
The raceways shall be installed in accordance with the requirements of Chapter 3
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Good question but a box isn't a raceway so I don't see how 800.110(A)(1) applies to boxes.
Well if you have to use raceway, you have to use pullboxes to not exceed the 360 degrees.
mwm1752
Senior Member
- Location
- Aspen, Colo
Raceway. An enclosed channel of metallic or nonmetallic materials designed expressly for holding wires, cables, or busbars, with additional functions as permitted in this Code.
I'm not sure we agree on that. never seen a busbar in e.m.t.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
I would say that would make the pull box just another raceway segment.
- Location
- Massachusetts
Pull boxes are not raceways.
You may never have seen bus bars in EMT but you can find them in wireways.
It in the listing, pull boxes are not listed as raceways.
mwm1752
Senior Member
- Location
- Aspen, Colo
This response addresses good practice methods -- So what is your answer to the OP -- Yes or No?
- Location
- Massachusetts
I really cannot answer.
For one thing the OP mentions article 800 when it could be article 725. The requirements are different.
The other thing is my lack of familiarity with this area of the NEC. I have run a fair a amount of voice and data conduits but never had to worry about the NEC, the specs where much more restrictive.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Or maybe a conduit body.
Certain cables need to meet certain bending radius requirements in order to meet certain performance standards. Tight bends is often not allowed without effecting performance levels. That is what I was taught, yet the guys that I've seen that specialize in data wiring don't seem to follow those rules:roll:
mwm1752
Senior Member
- Location
- Aspen, Colo
Where would you find communication conductor properties? Box fill is based upon conductor cir mills. The only code to apply with pull boxes in this caes seems to be the conduit size entering/exiting having a requirement of separation.
300.34 Conductor Bending Radius
- Location
- New Jersey
- Occupation
- Journeyman Electrician
300.34 is for over 1000 volts were you using that as an example?
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
check with cable manufacturer for minimum bending radius.
Cat 5,6 cables will still work if you bend too tight, but may not get maximum data transfer speed the cable is capable of. Zip tying bundles too tight can effect maximum data transfer speed from what I can recall. They have carefully selected twist rate per length of each pair to get maximum data transfer speed, any disruption of that twist rate, like a pinched cable or too sharp of a bend can effect data speed.
They likely have recommended raceway fill / pulling tension information as well.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- Semi-retired engineer
these kind of cables are often not physically very strong. Yanking on them can damage them more easily than with regular conductors. it is best to take more care with them.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
It is not so much a disruption of the twist pitch as a disruption of the wire spacing (mashing) that causes a transmission line impedance bump which induces rate limiting reflections.
You can see the crush point on a sufficiently sensitive TDR.
- Status