Oil immersion Oil immersion:
The marking for this protection technique is "o".
is defined as a type of protection where electrical equipment is immersed in a protective liquid in such a way that an explosive atmosphere that may be above the liquid or outside the enclosure cannot be ignited.

This method is also recognized for use in Class I, Division 2 areas. This protection method is often used for high-voltage contacts in high-current circuits and some other electrical contacts that would otherwise produce arcs when they open or close. Otherwise this method is not very common.

LocationsLocations:
This protection technique shall be permitted for equipment in Class I, Zone 1 or Zone 2 locations.

NOTE: This is an unformatted excerpt from our online fire protection training library.