What is Shackle Insulator : Working & Its Applications

The insulators are used in transmission lines that are available in different types like pin, strain, suspension, solid core line, guy strain, busing, post, stay and shackle insulator. In the medium to high voltage systems, strain and suspension insulators are used. Similarly, in low voltage systems, stay & shackle insulators are used. Insulators play an essential role in electrical systems to avoid surplus electrical current flow toward the earth from the conductors. These are essential devices in the power system due to high resistance. This article discusses an overview of the shackle insulator and its working with applications.

What is Shackle Insulator?

Definition: An insulator that is used in distribution networks that works with low voltage is known as a shackle insulator. This insulator is also known as a spool insulator. These insulators can be worked in two positions like horizontal otherwise vertical. At present, the usage of this insulator has decreased because of the underground cable used in distribution purposes.

Shackle Insulator
Shackle Insulator

The insulator’s tapered hole distributes the load more consistently & also reduces the possibility of fracture once loaded heavily. The shackle insulator includes a conductor within the groove and it is fixed by using a soft binding wire. The shackle type insulator diagram is shown below.

Shackle Insulator Construction

The shape of the shackle insulator is round and it has a hole in the middle for bolting. A 25mm wide galvanized plate is available at both sides of the insulator. The other side of the plates is arranged in the region of the pole. The conductor is fixed within the channel and that is secured by using soft binding wires. These insulators are effective compare with strain insulators when the distribution line alters its angle.

Construction of Shackle Insulator
Construction of Shackle Insulator

There shackle insulators are available in three different sizes like (50 mm x 65 mm), (75 mm x 90 mm) & (100 mm x 115 mm). Generally, the 75 mm x 90 mm & 100 mm x 115 mm sizes of insulators are applicable in main lines, whereas the 50 mm x 65 mm size insulator is used in house to provide low voltage connection.

Shackle Insulator Working

The surface of this insulator must be covered so that water cannot flow through it. The raw material used in this insulator is porcelain and it is aluminum silicate (Al2SiO5). This material is combined with feldspar, plastic kaolin & quartz to get final porcelain insulator material.


The tapered hole in this insulator will distribute the load more equally & reduces the chance of fracture once deeply loaded. The conductor within the groove of this insulator can be set using the soft binding wire.

Applications of Shackle Type Insulators

The applications of this insulator include the following.

  • It is used in a distribution system by arranging in between tower & conductors to support & insulate.
  • These insulators are used in overhead lines with low & medium voltage.
  • This insulator is used with a bolt by placing on the pole otherwise telegraph to avoid outflow current from conductors
  • It can be used in both positions like horizontal & vertical position.

Advantages and Disadvantages of Shackle Insulator

The advantages and disadvantages are

  • These are extremely dependable for conductors
  • These are designed to meet up the demands of electricity.
  • These are used in vertical as well as horizontal positions.
  • Porcelain Insulators bears a high amount of current and temperature
  • The finest solution for maintaining protection in different electrical appliances
  • These are applicable for low voltage distribution networks only


1). What is a shackle insulator?

An insulator that is used in low voltage distribution lines is known as a shackle insulator.

2). What is an alternate name of a shackle insulator?

This is also known as a spool insulator.

3). What are the common conductors and insulators?

Copper, gold, silver, and aluminum are conductors whereas air, glass, plastic, wood, and rubber are insulators.

4). Why do we require an insulator?

It protects the devices by opposing the flow of current.

5). What is the strongest insulator?

The strongest insulator is Aerogel.

Thus, this is all about an overview of shackle insulator which includes construction, working, advantages, and applications. These insulators are used frequently in low voltage distribution lines in a horizontal or vertical position. The arrangement of these insulators can be done to the pole or cross arm with the help of a bolt. Here is a question for you, what are the different types of insulators?