What is an Insulator? Why we need them?

Insulators

Insulators are those material that doesn't allow flow of electric current through them when Electric Potential is applied across it like wood, rubber, plastic, paper, glass, air vacuum etc. Also Electric wires are covered with insulated coatings to avoid shocks by directly contact with electric wires carrying current.

What is an Insulator

As shown above copper wires carrying current are insulated with insulating material to avoid shocks.

Why we need Insulators? 

As already discussed that Insulators don't allow flow of electric current through them so we can use insulators at that places where flow of electric current is to be restricted like in electric cables where Electric conductor i.e. copper, Aluminium is covered with insulated material to avoid current flow in its vicinity. 

Insulated Cables used at Buildings

Since Electric Cables are used at Commercial buildings,residential buildings etc so If current flows outside wires then it spread over whole building, walls etc and any body get shock which results to fatal/Non-fatal accident. So to avoid such kind of casualty we need Insulators.  

Insulators are also used at Electric Lines hanging over PCC/Steel Tubular Poles usually seen near by houses, Since Aluminium Conductor is tied to Poles which is also made of Steel and steel is also good conductor of Electricity.

Electric Pole carrying Conductor

 So if we directly connect conductor with poles then it result in current flowing through Electric poles which lead to grounding of electric current because poles are erected on ground. In that case If any body touches that pole then He/She may get shock which would be very dangerous. Also Heavy current starts flowing to ground due to low earth resistance which would lead to Transformer and various Electrical equipment damage. So without using Insulators there is chances of huge loss of life and finance, Also we can't imagine Electricity transmission without Insulators. So we can only tied conductor to Electric Poles by using Insulators not directly.

Also as shown in above Image It is found that Aluminium Conductor is not directly tied to Electric Pole, Conductor is tied to Insulator and Insulator is attached to Electric Pole so there is no direct contact found between conductor and Electric Pole. Since Current flows through Aluminium Conductor which is insulated from Electric Pole by Disc Insulator so no current flows through Electric Pole and only travels through conductor which is a safe and reliable transmission, So in this way Electric Transmission takes place.