Direct Burial Fiber

[MAK]

What is the minimal burial requirements for a direct burial fiber optic cable? The location is about 1800' of a grass area at an apartment complex. The reason I am asking is an electrician my boss had hired stated that he would replace a damaged fiber optic cable with direct burial and he would only need to dig down 6 inches to do it. Table 300.5 column 1 shows 24" (I think). Am I misinterpreting something? 6" depth just seems way too shallow to me.

 

[JohnJ0906]

Is fiber optic even covered by the NEC?

edit to add: Never mind. I looked for "fiber optic", not "optical fiber" (770)

 

[don_resqcapt19]

I see nothing in Article 770 that modifies the depth rules in Article 300, therefore they apply.
Don

 

[acrwc10]

What is the minimal burial requirements for a direct burial fiber optic cable? The location is about 1800' of a grass area at an apartment complex. The reason I am asking is an electrician my boss had hired stated that he would replace a damaged fiber optic cable with direct burial and he would only need to dig down 6 inches to do it. Table 300.5 column 1 shows 24" (I think). Am I misinterpreting something? 6" depth just seems way too shallow to me.

Most picks have a 10'' to 12'' point on them, and are not owned by brain surgens. With that in mind I hope at the cost of fiber repair it wouldn't matter if you could put it 6'' shallow. The deeper the safer.

 

[curt swartz]

Don, 770.3 say that only those sections of Article 300 referenced in this article shall apply to optical fiber cables and raceways. I don?t see any reference to directly buried fiber cable in article 770.

 

[Jim W in Tampa]

This is something i would want plenty deep and foil tape.Far to costly to risk at 6 inches.Sometimes legal is not the best answer.

 

[MAK]

This is something i would want plenty deep and foil tape.Far to costly to risk at 6 inches.Sometimes legal is not the best answer.

I agree but someone above me thinks the up front cost to dig that long a trench at the 24" depth is not justified. Bare in mind that this existing run has already been damaged by a car driving over it. I think if I need to dig it up in the future I could just follow the guy with the lawn mower, I'm sure he will find it.:grin:

 

[stephanie royer]

back hoes find it really easy too. Put it at 24". Much cheaper than having me come out after the fact and fixing it!

 

[don_resqcapt19]

Curt,

Don, 770.3 say that only those sections of Article 300 referenced in this article shall apply to optical fiber cables and raceways. I don’t see any reference to directly buried fiber cable in article 770.

Thanks...I guess I just skipped over that. I should have known as I have cited the equivelent section in 725 a number of times.
Don

 

[nakulak]

personally, I think that anything with the words "direct burial" should read "direct burial at 24" minimum". I'm tired of digging this stuff up.

 

[zbang]

The location is about 1800' of a grass area at an apartment complex. The reason I am asking is an electrician my boss had hired stated that he would replace a damaged fiber optic cable with direct burial and he would only need to dig down 6 inches to do it.

Is this a single 1800' run? Any handholes/boxes along the way? Depend on $$, the ground, further damage potential, etc, you might consider a few handholes with the new cable just looped through so that individual sections can be replaced. Even at 24", the Underground Cable Locater (aka backhoe) can still snag it.

 

[petersonra]

My understanding is that it is not required to be buried at all. It can be laid on the ground if you want.

Its all about how often you want to repair it, and how much money the apartment complex has to put it in up front.

I would want it put in deep enough that casual digging would not disturb it. not real sure what that translates to in the real world.

 

[Jim W in Tampa]

Reason its being replaced is cause it wasnt deep enough first time.One would think they learned from this but perhaps they want job security.Now if my boss says 6 inches then thats what it will be.

 

[petersonra]

Reason its being replaced is cause it wasnt deep enough first time.One would think they learned from this but perhaps they want job security.Now if my boss says 6 inches then thats what it will be.

In the real world, a 6 inch deep trench means there will be plenty of places where the thing is really only buried 2 inches deep. These things tend to move around when the trench is closed and the main way they move is up the side of the trench.

The cable company has a neat toy they use around here. It buries the cable in the ground with no trenching required. It looks like it just slits the ground about 8 or ten inches down and the cable is inserted and the slit closed all in one motion.