Underground cable installation methods

The solid system of cable laying is mainly performed where the cable is laid in the wood, cast iron, or another nonsoil surface. Normally cable is laid in the manner which provides good mechanical strength to cables. This system is much appropriate for solid based systems.

Normally the cables are filled with bituminous materials for providing protection and avoid heat dissipation. Then another Asphalt cover layer around the cable and bituminous material area for further protection. The system is expensive compare to the direct laid system and heat dissipation capacity is not much good compere with other systems.

However, even if you have an electrician make the final hookups at the service panel and connect the outlets and light fixtures in your garage, you can save a lot of money on the most labor-intensive part of the project—laying the underground cable from the house to the garage or outbuilding.

There are a variety of ways electrical wiring can be run underground. The method you use may depend on what is allowed or recommended by your local Code authorities, so always check with the local building inspections office to find out what is recommended in your community. Generally speaking, though, the National Electrical Code allows for three means of running underground circuits:.

Although it is theoretically possible to simply extend an existing house circuit by running an additional cable out to a garage or other outbuilding, most local Code requirements will require you to run one or more new circuits. Here are standard recommendations:. Extending an existing circuit to an outbuilding should be done only where the existing circuit is already serving a deck or outdoor outlets, and you must make sure that the new lights and outlets in the garage will not exceed the capacity of the circuit.

And make sure a simple circuit extension is allowed by your local Code. The process is similar for direct-burial of UF cable or when using rigid metal conduit. The steel ropes are bundled into a resistant layer.

The aluminum layer prevents water. Fiber optic cable. These fiber optic cables carry optical signals that are transmitted by wavelength-based optical multiplexing, with transmission rates of up to terabytes per second.

Besides, cable manufacturers use optical repeaters to increase the strength of the waves when traveling long distances. The entire cabling system is powered by electricity running in copper pipes in the cable.

The lifespan of the above underground cables is about 10 years, the cost of production and installation depends on the length of the cable line. Underground cable installation methods? We also do not use satellite networks to replace undersea cables because the cost of terabytes of data per line will cost no less than a billion dollars. The thickness of the cable depends on where it will be installed.

Blowing does not use a missile - instead, the pulling force on the cable is due to fluid drag of air rushing along the cable - this pulling force is distributed along the cable length. A mechanical pushing device is common in both methods. It is common wisdom that hydraulics can give you higher forces than pneumatics. Mindful of this, a blowing machine with a pneumatic drive is recommended for cables up to 15mm in diameter and a blowing machine with a hydraulic drive is recommended for cables with a diameter in the range from 14 - 32mm.

The key parameters when installing fiber cable in ducts are blowing distance and time. Typical installation speeds are meters per minute under an air pressure of 10 bars atmospheres. Most routes can be blown with a 10 bar supply.

Smaller diameter and lower weight cables make possible larger blowing distances, so blowing cable is perfect for the new generation of microcables. The maximum cable push force will decrease as the duct inside diameter increases, reducing the achievable blowing distances. Blowing distance is directly related to the weight of cable, the pressure used and, friction from the inside of the microduct.

Cable can be successfully blown further than 2-km when blowing heads are used in tandem. Additional air can also be inserted further down, to achieve more distance.

Determine where coupling of ducts are necessary. Survey the route for the accessibility of terrain for the use of the intermediate mid-point fiber blowing equipment. Identify specified ducts to be utilised. Strictly speaking, the purpose of the cable is to protect the fibers during installation and the service lifetime.

Cables share some but not all characteristics and you need to ensure you install the cable type appropriate for the application. Micro cables are designed with high-density polyethylene HDPE outer sheaths to minimize friction with the inner surface of micro ducts.

They are also designed with the necessary stiffness properties to resist buckling forces and to negotiate changes in direction. The cable on the drum must be covered until just prior to installation to protect the jacket from heat due to exposure to the sun and getting dirty. Air-Assisted Installation Practices Consider a very long link installation. Cable reels are typically supplied containing 4-km of cable.

Mindful of this, reels are placed midway of a 4-km length. Next, the figure-8 end will be jetted in the other direction. One ought to be able to install 4-km of cable in one placement of the cable drum and blowing equipment consisting of; 2-km of cable jetting in opposite directions with 2-km of "figure-eighting" in the center.

Adding more air blowing to a microduct further down can also increase the achievable distance. If at some point the cable movement slows down during the blowing process, then instead of taking a 2-km run, the jetting could be reduced to only 1-km. Now proceed with the sponge test. Wet the sponge slightly with blowing lubricant.

Place the tight-fitting foam sponge inside the microduct. At a pressure of 10bars, blow the sponge through the microduct. If excess water or dirt exits the microduct, repeat the process. Mandrill Test One can test ducts for bends, kinks or blockages that may hinder blowing cable by doing a mandrel test to see if one can blow a sample down the duct. The sponge test MUST precede this test - a mandrill can damage a dirty duct.

Use a 40mm 1. Use no more than 3-bar of pressure to blow-though the mandrill. At the receiving end, a DIT catcher must be used. Always inspect the condition of the emerged mandrill, visible grooves is an indication of duct indents.

Pressure Test A pressure test checks for coupler leaks or microduct punctures that could affect blowing cable. Fit a high-pressure end-cap to the duct under test on the far-side. Gradually build the pressure up to 10 bars atmospheres. Test all coupling used for this test for leaks, using soap, water and a sponge.

Connect the air feed and leave this open until the pressure in duct stabilizes at 10 bars. Close the air valve on the test assembly and monitor the pressure gauge for 5min. If the duct fails DIT tests, consult with the relevant authority on whether to use an alternative duct or to repair of the designated duct. This is determined and provided by the microduct supplier.

It is wise to always verify this by checking the provided spec sheet. Cable Blowing Lubricants Adding a small amount of lubricant to a tight-fitting foam carrier sponge before blowing it through the duct, will provide an open and lubricated pathway.

It is argued to give better results compared to coating both the duct and cable with lubricant.