Dielectric Strengths for Insulators

Chapter 3 - Conductor And Insulator Tables

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Dielectric strength in kilovolts per inch (kV/in):

Material* Dielectric Strength (kV/in)
Vacuum 20
Air 20 to 75
Porcelain 40 to 200
Paraffin Wax 200 to 300
Transformer Oil 400
Bakelite 300 to 550
Rubber 450 to 700
Shellac 900
Paper 1250
Teflon 1500
Glass 2000 to 3000
Mica 5000

* = Materials listed are specially prepared for electrical use 

 

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