How deep should you bury your copper feeder cable, fiber cable?

One of the most common questions we get is "How deep am I going to bury this wire" when it comes to our outside plant copper PE89 cable and outside plant fiber optic cable. Let's find out.

Most OSP cable runs are never as easy as digging a trench, lay cable, done. Your burial depth will be affected by a number of things, for example:

- Crossing under railroad tacks, under roads and highways

- Lakes, ponds and rivers

- Natural obstacles like rocks and trees

- Outside industrial locations with possible soil contamination

- The Frost Depth Line for your location

Now that your thinking about your entire run a bit more, your copper cable should be placed at a minimum depth of 24 inches (610 mm). However, don't only think about what obstacles are in the way of the trencher but find out what future plans the property may have. For example, maybe an area of your run has future excavation on it's mind. Road grading alone takes 24 inches of the top, so you should bury your cable at least 48 inches. You should also double check the requirements of your local code.

If your installing an OSP fiber optic cable, they should be buried at a minimum depth of 3.28 feet (1 Meter) but once again, think about the future!

Site conditions will also be important when selecting your bore depth. Pipelines, sidewalks and roads are just a few examples of what will influence that decision. In these cases the AHJ (Authority Having Jurisdiction) and owner set the minimum bore depth.

You also want to install an armored fiber optic cable for direct burial installations. An "Outdoor Rated Cable" is not enough to be warrantied. You must have an armor for direct burial applications.



Enclosures should provide sufficient space for splicing and proper storage. Enclosure can be in-ground or above ground type. Marker post are recommended to be placed at these locations. Don't forget, to prevent rodent and insect damage it's recommended that all in-ground enclosures with an open bottom have at least 6 inches of tamped gravel that covers the bottom of the enclosure. Pedestals should have gravel under it for at least 6 inches as well.

Oh, don't you feel better. Now install that cable!

"By Mercy Salinas"

Outside plant cable, single armored or double armored?

The most popular Cat3 telephone cable for underground direct burial installations is your PE89 constructed cable. You might of also looked into the United States Department of Agriculture's Rural Electrical Administration (REA) specification for filled telephone cables with expanded insulation to make sure you had what you're looking for.

Let's take a look at a PE89 Aluminum Single Armored Cable from our YouTube Channel



Now let's look at a PE89 (CACSP) Double Armored Cable.



As you can tell these cables are the exact same except the armoring. In section 9.3 of the REA specification a double armored cable is labeled as a (CACSP) for coated aluminum coated steel polyethylene cable.

When might you consider a double armored cable? On a personal level, I believe that the single armor is more then sufficient to support rodents from getting to this cable. The jacket alone is very durable and my hat goes off to the rodent that chewed through that!

Most of our direct burial cable sales are with a single armored but you might want to spend some time researching the installation area for what kinds of rodents are around and if it's a more populated rodent living area.


You might want to check out the North American Rodents Action Plan for more information.

It might not be a bad idea to also install a double armored cable where it may be submerged in depths of 40 feet or more. Here are some additional tips to consider for underwater installations.
    


I hope we've shed some light on this commonly asked question. Now it's time to figure out what you're more comfortable with, single or double. Wish it was as easy as deciding single or double from In-N-Out burger.


Questions? Don't hesitate to leave them below.

"By Mercy Salinas"

Tips for networking buildings together with direct burial cable

External wiring to the building is called outside plant cabling. Outside plant cabling can support a wide variety of communications services such as telephone, data transfer, live video, security, building automation control systems and any other low voltage circuitry.

Keep in mind that you must install OSP cable in compliance with National Electric Codes (NEC), National Electric Safety Code (NESC), utility franchise regulations and local building codes.

Before you start laying your cable down OSP cable installation should be based on a 10 year outlook plan. You may consider that the building owner may sell portions of the property so it may be necessary to obtain property easements. Keep an eye out if the cable run is going to cross railroad tracks or other utility company right of way or a natural occurrence such as a pond or stream.


Your OSP cable run will need to be secure. You'll need to provide an alternate route in case of disaster recovery, location of local exchange carrier facilities and the physical terrain of the campus. Extra pathways should be planned for maintenance purposes. It's typically a good idea to check in with your local exchange carrier regarding their facilities within, or adjacent, to the building.

Three pathways are used in outside plant construction. Aerial, underground conduit and direct burial and they can be used in any combination. Today we're going over direct burial installation.

A direct burial cable system is similar to a buried coduit system and has many of the same advantages but, the disadvantage is the capacity cannot be increased. Your cable also doesn't have as much mecanical protection as a buried conduit system.

Things to consider are type of soil and subsurface conditions, the possibility of joint trench use, and the back-filling method. The minimum depth of the trench should be 24 inches unless the local code requirement differs. If a possibility exist of your OSP cable being dug up by accident you may want to bury it deeper for added protection. Continuous planks should be used and placed 1ft below grade level for visual warning. (Trenching in action below).

For direct burial fiber optic cable you need to put down a copper conductor along with your fiber so that your cable can be located by a cable locating instrument in case you need to identify where your underground cable is in the future.

When back filling your OSP cable examine and use clean backfill material. The soil should not have any sharp objects or large rocks that could damage your cable during your backfill. After your backfill is complete your now ready to terminate your cable.

Special thanks to Electrical Construction and Maintenance.

Questions comment below. Thanks!

"By Mercy Salinas"