Dielectric Strength of Insulating Materials
The dielectric strength of a material is the ability to the material to act as an insulator.
The dielectric strength of a material is the voltage that a material of a given thickness will resist. With higher voltage than the dielectric strength a spark will pass through the material.
| Material | Dielectric Strength | |
|---|---|---|
| (106 V/m) | (V/mil) | |
| Mica (muscovite) | 39.4 | 1000 |
| Glass | 35.5 | 900 |
| Mica (phlogopite) | 31.5 | 800 |
| Porcelain (electrical) | 31.5 | 800 |
| Steatite | 29.6 | 750 |
| Rubber, hard | 27.6 | 700 |
| Rubber, silicone | 23.6 | 600 |
| Polystyrene | 23.6 | 600 |
| Pyroxylin | 23.6 | 600 |
| Rubber, buna | 20.3 | 515 |
| PTFE | 19.7 | 500 |
| Vinylidene chloride | 19.7 | 500 |
| Fish paper | 19.7 | 500 |
| Methyl methacrylate | 18.9 | 480 |
| Cellulose acetate | 15.8 | 400 |
| Casein plastic | 15.8 | 400 |
| Shellac | 15.8 | 400 |
| Varnished cambric | 15.8 | 400 |
| Alumina | 13.4 | |
The dielectric strength is usually given in volts per mil where 1 mil equals 0.001 in, or volts per meter.
- 1 V/m = 2.54×10-5 V/mil
- 1 V/mil = 3.94×104 V/m
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