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Running fiber to another building

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by ltheodoru 1 view

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I am applying for a grant but I must come up with the best method to run fiber from our high school to our middle school about 1/4 mile away. Because of the monthly or annual fees in leasing lines, I would prefer to own the fiber by digging a trench and laying it in there. Our facilities director seems to think it would be a fairly simple matter to do that especially since the parking lot is going to be ripped up next summer anyway. He does not think conduit is necessary - that it can just be laid in the trench as it is dug by a special machine. Any thoughts or advice on this?

6 replies

by tonythetiger

Fiber isn't affected by lightning, so there's no reason to put it underground. It will be less expensive to go aerial.

by gario

Direct burial is fine if you'll never need to run other cable in the future. We use conduit here due to weather (Florida) and ground water. You might also consider a "bore" instead of trenching so you don't have to rip of the parking lot. Use loose tube variant fiber.

by bman

Best practice is to use conduit. Like stated already, if it needs to be replaced (nothing like trenching, laying it and burying it only to find out that you have a defect somewhere) or you want to expand (I have no idea how many pair you plan on running) shooting through conduit is easier and cheaper than tearing up the trenced route in the parking lot.

I don't know if you partnered with your municipality or if this is internal to your school district BUT a few other things though to do...Run a trace wire for locates. The last thing you want is in the future to have a utility or public works need to bore under the parking lot on some project and not know exactly where the fiber is. Have someone from your municipality's GIS department GPS the route and depth and plot it on a map for future reference.

by kdawg360

Best practice for running fiber is to place schedule 40 conduit (reel fed) at a depth of 48-60 inches. Since you're digging up the parking lot anyway, trench the length of the parking lot then consider using a directional drill to bore the balance of the run; this will reduce the time and cost to restore landscaping if this is a consideration.

Make certain to 'locate' existing utilities by calling the Utility Notification Service in your state prior to any excavation. Protect your fiber by accurately documenting the run on an 'as built map' of the property, lay marker tape along the trench line approximately 18" above the conduit (partially back fill then lay the marker tape), and/or pull a marker cable for locating to prevent future damage.

Any competent underground utility contractor would tell you the same.

by jdgretz

What ever you think you need, at least double it, and if I had my way, double it again. Fiber is cheap and it shouldn't increase the labor cost (much) to pull 12 strands as opposed to 4 strands.

The last big pull I was involved with was 400 strands going under a state highway (talk about needing permits!!) perpendicular to MAJOR electric and gas lines - man, that could have been exciting if the boring machine was off a bit.

by ltheodoru

I talked to our facilities director who told me that we could not trench because of ledge, so I got a quote for running it on poles. He then told me that there were no poles going to the building. I knew the services had to be getting to the building somehow, but he did not have any information. I then started making phone calls to the town, the phone company, and the electric company. Finally I spoke to someone at the phone company who not only looked up the records but offered to meet me after work (he was a town resident). He and I then located the pole after which the services ran underground, and we found existing conduit. I showed this to the contractor who would be running the fiber, and he said that he could use the conduit.

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