This part of IEC60079 specifies the requirements for the design, construction, testing and marking of Ex Equipment and Ex Components with type of protection liquid immersion “o” intended for use in explosive gas atmospheres. Ex Equipment and Ex Components of type of protection liquid immersion “o” are either: Level of Protection “ob” (EPL “Mb” or “Gb”) Level of Protection “oc” (EPL “Gc”) For Level of Protection “ob”, this standard applies where the rated voltage does not exceed 11kV r.m.s. a.c. or d.c. For Level of Protection “oc”, this standard applies where the rated voltage does not exceed 15kV r.m.s. a.c. or d.c. NOTE Requirements for higher voltages are under consideration. This standard supplements and modifies the general requirements of IEC60079‑0 . Where a requirement of this standard conflicts with a requirement of IEC60079‑0 , the requirement of this standard takes precedence.