HELICALLY FORMED FITTINGS

Helical fittings are composed of multiple helical rods which are manufactured for a particular application meant for specific conductor that are in separated or pre-assembled form, straight or looped. Helical fittings are now already in use for a wide variety of applications. However, the range of its application continue to expand. There may be many more applications hidden in the womb of the future, which we cant even foresee today. This presentation in respect of the application of helical fittings mainly refers to T&D application especially to the use on overhead lines and distribution systems. Helically formed accessories can be used as dead end termination, to support and to connect conductors, cables. In addition helically formed accessories are used to protect or to repair conductors, for attachment to pin insulators, as spacers on bundled conductors and for anchoring the street lighting brackets. They are also successfully used to prevent birds from coming in accidental contacts with the conductors. Helically formed accessories have been used very successfully since 1950. The employment of helical fittings is not at all limited to overhead lines only. Helically formed accessories in a large measure are also used for the construction of antennas, radar stations & for providing support to the columns in case of pre-engineered buildings & for anchoring submarine cables to the ships during periodic maintenance or repairs. The effect of helical fittings is mostly based on the principle of development of a low unit clamping strength by uniformly distributing the clamping load over a large cross sectional area. The inside diameter of the unapplied helical rods is slightly smaller than the outside diameter of conductor, cable or solid rod.

Helically formed fittings provides a very good gripping force and prevents it from slipping under tension To ensure the full performance, the helical fitting must be matched to the outside diameter of conductor, cable or solid rod. In addition, helical fitting and outer strand of conductor must be of same lay direction. Unless specified otherwise, helical fittings are of right-hand lay on delivery. Hence, it is necessary to specify on order if helical fittings for left-hand lay conductors or right hand lay . In general, helically formed fittings are made from a material similar to that of conductor or solid rod in order to avoid bimetallic corrosion due to contact. The helical rods can be installed without use of any tool, therefore incorrect assembly is almost impossible. It can be detected by mere eyesight whether it was correctly installed. Hence, helical fittings can be installed by the workers with proper guidelines. Helical fittings are provided with a label stating for which function and for what conductors, cables the respective accessory is designed for. Helical fittings can be used:

  • for tension / dead end termination                                                                      helically-formed-fittings-500x500
  • for suspension
  • for splicing
  • Dead-End/ River Crossing Tower
  • for repairing
  • to armor
  • to protect against damage
  • to protect against abrasion
  • to reduce stress
  • to mark
  • to space
  • to damp vibrations
  • to pull (installation)
  • to shunt weak splices
  • as inter-phase spacer
  • to increase diameter of  stranded conductors, cables and solid conductors.

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