Rockwell Automation Low-Voltage Switchgear and Controlgear - Manual (Page 36)

6.1.3.2 Pollution degree
The pollution degree (see 2.5.58) refers to the environmental conditions for which the
equipment is intended.
NOTE 1 The micro-environment of the creepage distance or clearance and not the environment of the equipment determines the
effect on the insulation. The micro-environment might be better or worse than the environment of the equipment. lt includes all
factors influencing the insulation, such as climatic and electromagnetic conditions, generation of pollution, etc.
For equipment intended for use within an enclosure or provided with an integral enclosure, the
pollution degree of the environment in the enclosure is applicable.
For the purpose of evaluating clearances and creepage distances, the following four degrees of
pollution of the micro-environment are established (clearances and creepage distances
according to the different pollution degrees are given in Tables 13 and 15):
Pollution degree 1:
No pollution or only dry, non-conductive pollution occurs.
Pollution degree 2:
Normally, only non-conductive pollution occurs. Occasionally, however, a temporary conductiv-
ity caused by condensation may be expected.
Pollution degree 3:
Conductive pollution occurs, or dry, non-conductive pollution occurs which becomes conductive
due to condensation.
Pollution degree 4:
The pollution generates persistent conductivity caused, for instance, by conductive dust or by
rain or snow.
Standard pollution degree of industrial applications:
Unless otherwise stated by the relevant product standard, equipment for industrial applications
is generally for use in pollution degree 3 environment. However, other pollution degrees may
be considered to apply depending upon particular applications or the micro-environment.
NOTE 2 The pollution degree of the micro-environment for the equipment may be influenced by installation in an enclosure.
Standard pollution degree of household and similar applications:
Unless otherwise stated by the relevant product standard, equipment for household and similar
applications is generally for use in pollution degree 2 environment.
Tab. 2.3-3
Pollution degree according to IEC 60947-1 ed. 5.0.
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LVSAM-WP001A-EN-P - April 2009 2-8