Pollution degree of environment conditions IEC 60947–1

"Conventional number based on the amount of conductive or hygroscopic dust, ionized gas or salt and on the relative humidity and its frequency of occurrence, resulting in hygroscopic absorption or condensation of moisture leading to reduction in dielectric strength and/or surface resistivity".

Standard IEC 60947-1 distinguishes four pollution degrees:

• Degree 1. No pollution or only dry, non-conductive pollution occurs.

• Degree 2. Normally, only non-conductive pollution occurs. Occasionally, however, a temporary conductivity caused by condensation may be expected.

• Degree 3. Conductive pollution occurs, or dry, non-conductive pollution occurs which becomes conductive due to condensation.

• Degree 4. The pollution generates persistent conductivity caused, for instance, by conductive dust or by rain or snow.

PowerPacT circuit breakers meet degree 3, which corresponds to industrial applications.