Underground vs Aerial & Cable Laying Equipment

Cables for power transmission and communications networks within city areas are usually installed in trenches, directly buried in the ground utilizing cable laying equipment. In most countries Low Voltage, Medium Voltage & High Voltage distribution networks, mainly in rural areas, are overhead lines. However overhead lines present some disadvantages such as:

  • Occupy more area.
  • Have more visual impact.
  • Emanate electric fields that can affect people.
  • Are affected by storms and other natural disasters.

For these reasons power companies may choose the underground cable installation option, though more costly in the short term. Nevertheless, underground infrastructure has significant benefits.

  • Underground cables are not susceptible to storm damage
  • Underground cables are “invisible”, so no visual intrusion
  • Lower losses
  • No electric field emanates from underground cables
  • Magnetic field from underground can be managed, by use of shielding

Underground cables must be mechanically protected – power cables are required to be armored – and communications cables must be protected by conduits – plastic or metallic. The depth of the trench depends on local regulations and trenches must be laid with warning tape.

Cable Pulling

If not done properly may cause damages to the outer sheath of the cables, this leading, sooner or later, to a fault in the cable. Pulling tension must be in accordance with the type of cable and the instructions of the manufacturer must be followed. Further, the maximum bending radii indicated by the manufacturers must not be exceeded. For long runs, when installing cables in trenches specialized cable laying  equipment and tools must be used for safe installations. These include:

  • Cable Pulling Winch
  • Cable Drum Trailers
  • Cable Rollers

Cable Pulling Winch

A cable pulling winch is an installer’s best friend when used correctly. These devices are manufactured in various torque ratings. The pull and assist winch is a multipurpose machine used for the installation of power cable, telecoms cable and subduct. The unit can be positioned at the end of the pull or at a mid section to assist on longer duct or cable pulls.

Cable Drum Trailers

  1. Single axle: These trailers only have one axle and are fully equipped to drive with a full load across highways, boasting braking and lighting along with a maximum towing speed of 100km/h (62mph), making them perfect for the standard motorway. With their light weight and ease on the road, highway range trailers are predictably best at roadside applications such as installing underground cables.
  2. Multi axle: Used to carrying extremely heavy payloads of up to 50,000kg and are more suited for industrial size cable drums. Due to the extremely large weights that they are expected to carry, they are also much slower with a maximum speed of between 10km/h and 20km/h.

The sheer durability of multi axle cable drum trailers makes them excellent for demanding industrial applications, such as a construction or building site full of other heavy cable laying equipment.

Cable Rollers

  1. Cable rollers must be placed between 2 and 4m apart in the trench (Depending on cable size).
  2. Ensure that rollers can rotate freely. Grease or apply graphite lubricants if required.
  3. Check that skid plates, or corner rollers, are secure and in position

For more on cable laying equipment visit OSP Store and choose the right equipment specifically for your outside plant cabling needs.

Cable Laying Equipment