atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services Cabling Telephones Systems Wiring Fiber and Inner Duct

If you are running indoor/outdoor fiber in a drop ceiling, do you need inner duct.

Oh yeah, it's about 100 ft.

It depends upon the rating of the cable and the ceiling space. If it is plenum, then the I/O cable must be plenum rated. They make it in both plenum and non-plenum varieties. Do you know if the cable you'll be using is shielded?

Inner duct/coreflex is usually installed to add an extra level of protection. They do make it in a plenum form for situations as described by Ed. We would also sometime run 3 or 4 inner ducts in a conduit to facilitate future installations. Having said that there is no requirement to run coreflex, it just makes sense for protection. Sometimes it was cheaper to run conduit (just be careful of the bend radius).

Sam

I went ahead and ordered inner duct. It wasn't that much more for that short of a distance.

Thank you for you input.

Make sure you use riser/plenum rated inner-duct, regardless of the airspace usage above the grid. If using Carlon its usually opaque or milky orange.

I like the armored fiber for protection purposes as well. We use inner duct too.

I think the inner duct was designed to be installed inside conduit (like Silversam described) so that there is added protection from other wires and future wire pulls.

Oh, that's exactly what inner duct was designed for. Four 1" ducts turned a 4" traditional duct/conduit into four clear pathways. Using corrugated duct and due to the relatively light weight of fiber cable, you can get a lot done that way.

What people don't realize though is that fiber optic cable (especially that which is rated for OSP use) is very, very tough and technically doesn't require any external protection outside of the conduit/duct environment.

It is always safe to afford additional physical protection, but usually overkill.

"Oh, that's exactly what inner duct was designed for. Four 1" ducts turned a 4" traditional duct/conduit into four clear pathways. Using corrugated duct and due to the relatively light weight of fiber cable, you can get a lot done that way."
You may have misunderstood me?

I agree with OSP being very tough.

Interesting discussion. Related question, maybe it should be a new thread?

I have a fiber installation to a "temporary" office (trailer) consisting of a 40' run from a j-box, through a 13' conduit and across a 12' raised ceiling. The extra length is for up to the hangers and down to the inside panel plus the usual fudge factor. ST panel one end, SC the other. Twelve pair.

I was expecting a connecterized multi pair cable. What arrived was six duplex 40 foot fiber jumpers with the proper connectors. That's what we will use. We "like" to use what we are given around here.

I was also given a reel of black split inner duct. It will work. It is not labeled either riser or plenum. The space above the ceiling is not an air plenum.

How do you tell from the part number if it is rated for either?

Does it need to be plenum rated?