Riser fiber in PVC between buildings - bad idea?

[tmckeown]

We have some 62.5 fiber that we pulled from some buildings on our property before we went into demolition mode. the cable is in good condition. We have one remote building that is about 700' from the other buildings. We already buried 4" PVC between the buildings. I was planning on using the fiber we have. It's not exterior grade, but it will be in PVC.

Comments?

Tom

 

[skip555]

I would go ahead and use it . I beleive the only thing exterior grade will do for you is give you uv protection that you wont need becouse of the pvc.

 

[tmckeown]

It would sure save us some money to use what's already there.

 

[wires]

What else is going to be in the 4" conduit?

 

[tmckeown]

so far, the 4" PVC is empty, other than the fiber. I don't plan on filling it with anything else.

 

[franklin97355]

If there is even a remote chance you will put anything else in that pipe run your fiber in a 1 inch smurf tube inside the 4 inch.

 

[tmckeown]

why is that?
Is smurf pipe the orange tubing?

 

[skip555]

usually what I would call smurf tube is the blue, orange is interduct , but I am seeing the smurf in orange for low voltaqe

with interduct you could get one piece to run the whole 700' without couplers.

not to put words in franklins mouth but I would think you would do it to protect the fiber . I think its would be a good idea as I recall interduct is prety cheap

I would be intrested in hearing other reasons

 

[mikeydidit]

I would go ahead and use it. Like some of the others has stated, I would spend a little extra and use some innerduct. Then reguardless of who pulls what else through there, your fiber should be protected.

Mike Jones
Louisiana State University Health Sciences center

 

[tmckeown]

Thanks guys,
You've been a big help.
I love these forums.

Tom

 

[jeffbouldin]

I would plan on replacing it in the future. All PVC breaks, fills up with water which then breaks down the jacketing. In my experience about 70-90% of the time the cable will not pull through the PVC so you end up having to bury new PVC. Save yourself alot of future headache and run direct burial in the PVC. If no one ever accidentally digs it up you'll not have to mess with it for decades.

Jeff

 

[lopes1211]

I wouldn't put my neck out there to use it. Like Jeff says, all conduits leak, have temp extremes, etc.. When the cable fails 6 months down the road, you'll need to explain to the higher up that you knowingly used the wrong specification cable for the job. To me, it's not worth the risk.

-CL

 

[skip555]

i disagree that all conduit leaks , we live in a area with high water tables and lots of rain .

i find dry conduit all the time , especially in something as large as 4"

evan if it did how would moisture effect fiber ?

short out the light pulses

 

[daronwilson]

It is possible to keep conduit from leaking, simply it is almost exactly the same product used to keep water inside distributing it around your house. Often it is condensation that allows the water to collect in the conduit, or water entry from one end or the other.

What will the water due? I live on the coast, mild winters. However...several years back the Sprint fiber linking us to the valley went dark. They quickly shot it from both ends and found the problem right near where QWest takes over. After the obligatory finger pointing, in the icey winter evening they decended on the bridge of demarcation from both sides. The fiber went through a 2" conduit on the side of the bridge that had collected water inside it. So much water that when it froze it 'pinched' the glass. The fastest effective approach was to warm the conduit with a torch. Within 15 minutes of heating the affected area, the light snuck through and within 30 minutes they were back online.


Daron J. Wilson, RCDD
Solving 'Real World' problems

 

[skip555]

I didnt think of ice , definatley not a problem in my neck of the woods .

thinking about it the dry conduit I see is always terminating in telco closets .

 

[netmanrick]

Try this: How much is your data worth? Penny wise and pound foolish will get ya every time.
Listen to these guys who recommend direct burial.
Instead of pvc use armored conduit. If you ever have to splice the fiber you refer to(and someone does a crappy splice)any water in the pvc conduit will furthur degrade the splice.

That's my $.02 and I'm sticking to it!

Rick Harris
SC Dept of Motor Vehicles
Network Operations

 

[Jtodd]

With the cable not being OSP rated cable, any way you run it, it will be in jepordy of the elements. At a minimum, I'd run innerduct, but we use Maxcell, which is a flexible innerduct, so you can get 9 instead of 4 in a 4" conduit. But that won't help if the conduit gets wet.

As for PVC conduit, we've got a major upgrade project that is going to install several thousands of feet of Schedule 40 pvc conduit (all 4"). As long as it's installed correct, and the vaults stay dry (which not all of them do) the conduit will stay dry. Unless it is damaged. And that is going to be man made damage at that point. Which can be repaired.

If you want to be the safest from water issues, check the status of the conduit now to see if its wet. If its not, go with new indoor/outdoor fiber and your golden. If the conduit is wet, you'll need to research why as it may be crushed and impassable. If it just has standing water (from condensation as mentioned above) you'll absolutely need to use OSP cable, as inside rated cable will act like a wick and draw water into you vault/telecom room (especially if its plenum cable).

Justin T. Clausen
Physical Layer Implementation
California State University, Monterey Bay

 

[tmckeown]

Thanks for all the great advice on this. Since the cable is already installed and the 4" PVC will not have anything else in it, and it's dry and sealed, I think I will give it a shot. If I'm wrong, then I will be out the cost of having the fiber terminated.

Thanks for the help.